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1. gt ULOS H When we typeset on a half circle we should map the actual length onto a partial circle We denote the radius with an r and shift the pictures to the left startMPdrawing numeric r r len n Pi for i 1 upto n pic i pic i shifted r 0 endfor stopMPdrawing You can now use the following code to test the current state of the pictures Of course this code should not end up in the final definitions content index reference Page 404 TEX text startMPdrawing draw origin withpen pencircle scaled 5pt withcolor red for i 1 upto n draw pichi draw boundingbox pic il withpen pencircle scaled 25pt withcolor red endfor stopMPdrawing Later we will write a compact efficient macro to take care of rotation However for the moment so as not to overwhelm you with complicated code we will rotate each individual picture with the following code fragment startMPdrawing numeric delta extra radius rot delta extra radius for i 1 upto n rot i extratdelta pos i 5wid i len n 180 2delta endfor stopMPdrawing Typesetting in METAPOST Page 405 TX text Here we introduce a few variables that we can use later to tune the result a bit With delta the space between the characters can be increased while extra rotates the whole string around the origin The radius variable can be used to increase the distance to the origin Witho
2. direction specifier basic path join direction specifier direction specifier empty curl numeric expression pair expression numeric expression numeric expression METAPOST syntax Page 562 Syntax diagrams basic path join F ed tension tension controls tension tension numeric primary tension atleast numeric primary tension numeric primary and numeric primary controls gt controls pair primary controls pair primaryiandhpair primary argument symbolic token number or fraction number number number not followed by numberi METAPOST syntax Page 563 Syntax diagrams Page 564 Syntax diagrams scalar multiplication op number or fractioni not followed by add op number transformer rotated numeric primary scaled numeric primary shifted pair primary slanted numeric primary transformed transform primary xscaled numeric primary yscaled numeric primary zscaled pair primary xyscaled numeric or pair primary reflectedabout pair expression pair expressioni rotatedaround pair expression numeric expression xsized numeric primary ysized numeric primary xysized numeric or pair primary enlarged numeric or pair primary leftenlarged numeric primary rightenlarged numeric primary topenla
3. 75 0 seitiejoma Gl 25 Gl 1 metapost macro controls pair 0 0 controls 75 0 1 1 metapost primitive content index reference Page 589 Paths controls pair and pair 0 0 controls 75 0 and 1 25 1 1 metapost primitive tension numeric ORO O cencrionm nm Sem Glew 5 een Glee metapost primitive tension num and num COPOS 0 eee enssilo ae Sranda 2 ten Glee metapost primitive Reference Page 590 Paths tension atleast numeric CRO Gono tensionat least ECD metapost primitive OOE ele metapost primitive CO O emeal EO eB oo Cl 1 metapost primitive Reference dir numeric Reference Page 591 Paths ORO dares OFF Clap metapost primitive 0 0 left 1 1 metapost macro Page 592 Paths Op Origins Gl 1 metapost macro RO pen Cll metapost macro content index reference Reference Page 593 Paths 0 0 down 1 1 metapost macro pO coc HS5 AB amp Co fS5 25 oo Gol metapost primitive unitvector Reference Page 594 Paths origin unitvector 1 1 metapost variable origin dir 45 metapost primitive origin dir angle 1 1 metapost primitive Page 595 Paths fullcircle fullcircle i ee eee metapost variable unitcircle unitcircle metafun variable fullsquare fullsquare metafun variable Reference unitsquare fulldiamond unitdiamond Reference Page 596
4. Welcome to MetaPost These two graphics were defined and drawn using the following commands Later we will explain how you can set the line width or penshape in terms of METAPOST path p p Ocm icm 2cm 2cm 4cm 0cm 2 5cm icm cycle drawarrow p withcolor 625red draw p shifted 7cm 0 dashed withdots withcolor 625yellow Once we have drawn one or more paths we can store them in a picture variable The straightforward way to store a picture is to copy it from the current picture picture pic pic currentpicture The following command effectively clears the picture memory and allows us to start anew currentpicture nullpicture We can shift rotate and slant the picture stored in pic as we did with paths We can say draw pic rotated 45 withcolor red content index reference Page 45 Drawing pictures A picture can hold multiple paths You may compare a picture to grouping as provided by drawing applica tions draw Ocm Ocm 1cm icm draw 1cm 0cm Ocm 1cm picture pic pic currentpicture draw pic shifted 3cm Ocm draw pic shifted 6cm 0cm pic currentpicture draw pic shifted Ocm 2cm We first draw two paths and store the resulting cross in a picture variable Then we draw this picture two times so that we now have three copies of the cross We store the accumulated drawing again so that after duplication we finally get six crosses Z NLS NL ZN
5. startuseMPgraphic text split t ulcorner q urcorner q intersectionpoint q Typesetting in METAPOST Page 423 Talking to Tex llcorner q lrcorner q intersectionpoint q l q cutbefore t 1 1 cutafter b r q cutbefore b r r cutafter t stopuseMPgraphic In order to test what we have reached so far we draw the original path the left and right part of the reduced path and both the top and bottom point startuseMPgraphic text draw drawarrow p withpen pencircle scaled 1pt withcolor red draw t withpen pencircle scaled 2pt draw b withpen pencircle scaled 2pt drawarrow 1 withpen pencircle scaled 1pt withcolor green drawarrow r withpen pencircle scaled ipt withcolor blue stopuseMPgraphic Again we use includeMPgraphic to combine the components into a graphic startuseMPgraphic text includeMPgraphic text path includeMPgraphic text vars includeMPgraphic text move includeMPgraphic text split includeMPgraphic text draw stopuseMPgraphic Then we use useMPgraphic text to call up the picture content index reference Page 424 Talking to TEx The offset is not optimal Note the funny gap at the top We could try to fix this but there is a better way to optimize both paths We lower the top edge of q s bounding box by topskip then cut any part of the left and right pieces of q that lie above it Similarly we raise the bottom edge and cut off the pieces that fall belo
6. currentpicture currentpicture xsized size enddef Since we don t want to duplicate a graphic this time we show the dark alternatives colorcircle 4cm 5red 5green 5blue This kind of unsafe path calculations are very sensitive to breaking Changing the radius 4 into something else demonstrates this but we will not challenge this macro that much Therefore the 50 color circle shows up as A few applications This command is part of METAFUN and can be used to determine nice color combinations by also looking at their complementary colors colorcircle 4cm 7red 5green 3blue content index reference Page 504 Color circles The next circle that we draw shows the three main colors used in this document This circle is not that beautiful colorcircle 4cm 625red 625yellow 625white This definition can be cleaned up a bit by using transform but the fuzzy buildcycle s remain vardef colorcircle expr size red green blue save r g b rr gg bb cc mm yy save radius path r g b rr bb gg cc mm yy numeric radius radius 5cm pickup pencircle scaled radius 25 transform t t identity rotatedaround origin 120 r fullcircle scaled radius shifted O radius 4 rotatedaround origin 15 Page 505 Color circles r transformed t b g transformed t r rotatedaround center r 90 g rotatedaround center g 90 buildcycle buildcycle reverse r
7. defineoverlay my graphic uniqueMPgraphic name button background my graphic frame off Go Home firstpage You may wonder why unique graphics are needed when a single graphic might be used multiple times by scaling it to fit the situation Since a unique graphic is calculated for each distinctive case we can be sure that the current circumstances are taken into account Also scaling would result in incomparable graphics Consider the following definition startuseMPgraphic demo draw unitsquare xscaled 5cm yscaled 1cm withpen pencircle scaled 2mm withcolor 625red stopuseMPgraphic Since we reuse the graphic the dimensions are sort of fixed and because the graphic is calculated once scaling it will result in incompatible line widths C These graphics were placed with content index reference hbox bgroup scale width 5cm height 1cm useMPgraphic demo quad scale width 8cm height 1cm useMPgraphic demo egroup Imagine what happens when we add some buttons to an interactive document without taking care of this side effect All the frames would look different Consider the following example startuniqueMPgraphic right or wrong pickup pencircle scaled 075 fill unitsquare withcolor 8white draw unitsquare withcolor 625red currentpicture currentpicture xscaled OverlayWidth yscaled OverlayHeight stopuniqueMPgraphic Let s define this graphic as a background to some buttons de
8. drawarrow Ocm 7cm lft icm 7cm clip currentpicture to unitsquare xyscaled 7cm 8cm stopuseMPgraphic Page backgrounds Page 277 The basic layout As you can see the left graphic is defined as a series of rectangles The xyscaled macro is part of the CONTEXT files and saves some typing and space It is defined as a primary requiring both left and right operands primarydef p xyscaled q p xscaled xpart q yscaled ypart q enddef Zooming in on the top left corner only takes a few lines First we clip the correct part next we scale it up and finally we let the bounding box suit the left picture startuseMPgraphic layout 2 includeMPgraphic layout 1 clip currentpicture to unitsquare scaled 3cm shifted 0 5cm currentpicture currentpicture scaled 2 shifted 0 8cm setbounds currentpicture to unitsquare xyscaled 6cm 8cm stopuseMPgraphic This code demonstrates how you can reuse a graphic inside another one This strategy can easily be used to stepwise build or extend graphics The two graphics were put side by side with the following command Watch the use of line correction commands They optimize the white space around the graphic startlinecorrection blank hbox useMPgraphic layout 1 hskipicm useMPgraphic layout 2 stoplinecorrection Page backgrounds Page 278 The basic layout As soon as you want to make an electronic document you will want to use different areas of the scre
9. framed background demo circle This text is overlayed The background can be set to color screen an overlay identifier like demo circle or a comma separated list of those This text is overlayed gt The framed command automatically draws a ruled box which can be quite useful when debugging a graphic However in this case we want to turn the frame off framed background demo circle frame off This text is overlayed his text is overlayed In this case it would have made sense to either set the offset to a larger value or to set backgroundoffset In the latter case the ellipse is positioned outside the frame Enhancing the layout Page 228 Overlays The difference between the three offsets offset frameoffset and backgroundoffset is demonstrated in fig ure 4 1 While the offset is added to the natural or specified dimensions of the content of the box the other two are applied to the frame and background and don t add to the dimensions In the first row we only set the offset while in the second row the text offset is set to 3pt When not specified the offset has a comfortable default value of 25ex some 25 of the height of an x setupframed width 3 textwidth background demo circle startcombination 3 3 framed offset none framed offset overlay framed off set 0pt framed offset 1pt framed offset 2pt framed Loffset 4pt framed off set 3pt framed frameoffs
10. Because both graphics share code we have defined that code as a separate graphic that we include The only point of interest in this definition is the fact that we let meTarosT interpolate between the two colors using 5 IE startuseMPgraphic first numeric size delta size 2 5cm delta size 3 color mainshade topshade bottomshade centershade mainshade MPcolor funcolor topshade 9mainshade bottomshade 5mainshade centershade 5 topshade bottomshade stopuseMPgraphic The color funcolor is provided by CONTgxXT and since we want to use this graphic with different colors this kind of mapping is quite convenient The bunch of graphics is packaged in a combination with empty captions Note how we set the color before we include the graphic startcombination 5 2 definecolor funcolor red useMPgraphic second definecolor funcolor green useMPgraphic second definecolor funcolor blue useMPgraphic second definecolor funcolor yellow useMPgraphic second definecolor funcolor white useMPgraphic second definecolor funcolor red useMPgraphic third definecolor funcolor green useMPgraphic third definecolor funcolor blue useMPgraphic third A few applications Page 515 Fool yourself definecolor funcolor yellow useMPgraphic third definecolor funcolor white useMPgraphic third stopcombination We us
11. Once you are accustomed to the way METAPOST interprets specialists may say expand the source code you will start using if and for statements in assignments The previous code can be converted in a one liner using the pattern pat for i l upto n 1 x y endfor Osa The loop splits out a series of x y but the last point is added outside the loop Otherwise pat would have ended with a dangling Of course we need to replace x y by something meaningful so we get pat for i 1 upto n 1 if odd i fi w 2 i endfor 0 n We scale this path to the length needed The expression b a calculates a vector starting at a and ending at b In MeTAPOST the expression a b is identical to Va b Thus the expression xpart b a ypart b a calculates the length of the vector b a Because the unscaled spring has length n 2h scaling by the expression xpart b a ypart b a n 2h gives the spring the same length as the vector b a Because we have drawn our spring in the vertical position we first rotate it 90 degrees clockwise to a horizontal position and then rotate it through an angle equal to the angle in which the vector b a is pointing After that we shift it to the first point The main complications are that we also want to draw connecting lines at the beginning and end as well as support springs that connect arbitrary points Since no check is done on the parameters you should be careful in
12. al O10 vail OBO For similar reasons we may not assign a value using to such a z variable Within a metaPosT figure z variables are automatically saved which means that they can be reused for each figure So far we have defined the following segment of the logo The next expressions are used to define the second segment The third expression determines z7 to be posi tioned on the line z5 z6 where we extend this line by 50 z5 x4theight 2 y1 z6 x4 2y1 z7 1 5 z5 z6 A few applications Page 536 Simple Logos jens GC gak z Z az 5 3 However when we draw them using the right linewidth and color you will notice that we re not yet done A few applications Page 537 Simple Logos The second curve is similar to the first one but rotated over 180 degrees addto currentpicture also currentpicture rotatedaround 5 z2 z3 180 shifted height 4 height 2 In order to get the sharp edges we need to clip off part of the curves and at first sight we may consider using a scaled bounding box However when we show the natural bounding box you will notice that a more complicated bit of calculations is needed content index reference Page 538 Simple Logos The right clip path is calculated using the following expressions Watch how we use rt and top to correct for the linewidth numeric d 1x ly ux uy d line 2 lx 3d d 3 ly d ux rt x5 d 3 u
13. fill fullsquare xyscaled 6cm 1 5cm withcolor cmyk 5 5 5 0 fill fullsquare xyscaled 2cm i1cm withcolor cmyk 0 0 0 5 In figure 3 5 to 3 7 you can see some more colors defined in the CMYK color space When you display the screen version of this document you will notice that the way colors are displayed can differ per viewer This is typical for CMYK colors and has to do with the fact that some assumptions are made with respect to the print medium c 1 y 3 k 3 c 9 y 15 c 25 y 8 c 45 y 1 Figure 3 5 CMYK support disabled conversion to RGB Embedded graphics Page 220 Common definitions c 1 y 3 k 3 c 9 y 15 c 25 y 8 c 45 y 1 Figure 3 6 CMYK support enabled no support in METAPOST c 1 y 3 k 3 c 9 y 15 c 25 y 8 c 45 y 1 Figure 3 7 CMYK support enabled no conversion to RGB support in METAPOST Common definitions When using many graphics there is a chance that they share common definitions Such shared components can be defined by startMPinclusions color mycolor mycolor 625red stopMPinclusions The following is only true for CONTEXT MKII Users of MKIV can skip this section All metarost graphics defined in the document end up in the files mpgraph mp and mprun mp When processed they produce sometimes many graphic files When you use CONTEXT MKII and TEXEXEC to process documents these two files are processed automatically after a run so that in a next run the right g
14. lrcorner cp shifted 0 ypart lrcorner cp urcorner cp ulcorner cp cycle endgroup stopuseMPgraphic The core of the macro is the for loop Within this loop we draw groups of four plus one lines The draw path s look a bit complicated but this has to do with the fact that a mod returns 0 4 while we like to deal with 1 5 The height adapts itself to the height of the line The bounding box correction at the end ensures that the baseline is consistent and that the random vertical offsets fall below the baseline Because we want to be sure that n has a value we preset it by saying setupMPvariables fuzzycount n 10 In the table it makes sense to adapt the drawing to the lineheight but a more general solution is to adapt the height to the fontsize height 3 4 the bodyfontsize currentfontscale Shapes symbols and buttons In the table we called the graphic directly but how about making it available as a conversion macro In CONTEXT this is not that hard def fuzzycount 1 tx useMPgraphic fuzzycount n 1 def ineconversion fuzzy fuzzycount Because such a counter should not be that large we use tx to switch to a smaller font This also demonstrates how the graphic adapts itself to the font size We can now use this conversion for instance in an itemize To save space we use three columns and no white space between the lines The 2 broad directive makes sure that we have enough room
15. stopMPpage When you process that file with the context command you will get a PDF file that you can include in any application that can embed a PDF image In this case your exposure to CONTEXT is minimal Graphic buffers In addition to the macros defined in the previous section you can use CONT XT s buffers to handle graphics This can be handy when making documentation so it makes sense to spend a few words on them Embedded graphics E EE eh oe VAVATE HUTTE ntfaint U iiidid A buffer is a container for content that is to be re used later on The main reason for their existence is that they were needed for typesetting manuals and articles on Tex By putting the code snippets in buffers we don t have to key in the code twice since we can either show the code of buffers verbatim or process the code as part of the text flow This means that the risk of mismatch between the code shown and the typeset text is minimized startbuffer You are reading the METAFUN manual stopbuffer This buffer can be typeset verbatim using typebuffer and processed using getbuffer as we will do now An other advantage of using buffers is that they help you keeping the document source clean In many places in this manual we put table or figure definitions in a buffer and pass the buffer to another command like placefigure A very big table getbuffer Sometimes it makes sense to collect buffers in separate fil
16. B which can be shown to be the midpoint of segment A B startbuffer g def draw_midpoint pair pointM pointM lineCD intersectionpoint lineAB draw_dot pointM label 11ft btex M etex pointM enddef stopbuffer startbuffer 5 start_everything draw_basics draw_circles draw_intersection draw_bisector stand_out draw_midpoint A few applications Page 526 Growing graphics stop_everything stopbuffer As long as we place the graphics as individual insertions in our document everything is fine However if we wish to place them all at once or as we shall see later place them on top of one another in a fieldstack it makes sense to give them all the same bounding box We can do this by completing the start_everything and stop_everything commands startbuf fer a def start_everything path bb draw_basics draw_circles draw_intersection A few applications Page 527 Growing graphics draw_bisector draw_midpoint bb boundingbox currentpicture currentpicture nullpicture enddef def stop_everything setbounds currentpicture to bb enddef stopbuffer In figure 13 5 we demonstrate the effect of this redefinition For this purpose we scale down the graphic to a comfortable 40 of course by using an additional buffer We also visualize the bounding box startbuffer h def stop_everything setbounds currentpicture to bb draw bb withp
17. METAFONT and METAPOST CONTEXT Tools Distributions Conventions When reading this manual you may be tempted to test the examples shown This can be done in several ways You can make a file and process that file by Metarost Such a file looks like beginfig 1 fill fullcircle scaled 5cm withcolor red a graphic endfig end Don t forget the semi colons that end the statements If the file is saved as yourfile mp then the file is processed by mpost mem metafun mem yourfile The results are available in yourfile 1 and can be viewed with GHOSTSCRIPT You don t need to close the file so reprocessing is very convenient Alternatively you can use CONTEXT In that case a simple file looks like starttext startMPpage fill fullcircle scaled 5cm withcolor red stopMPpage Conventions startMPpage fill unitsquare scaled 5cm withcolor red stopMPpage stoptext If the file is saved as yourfile tex then you can produce a PDF file with context yourfile This will use LUATEX and CONTEXT MKIV to produce a file with two pages using the built in meTarost library with METAFUN When you use this route you will automatically get the integrated text support shown in this manual including OPENTYPE support If one page is enough you can also say startMPpage fill fullcircle scaled 5cm withcolor red stopMPpage So when you have a running CONTEXT on your system you don t need to bother about installi
18. Now is this TeX or not setMPtext 2 See what happens here setMPtext 3 Text streams become pictures The MPbetex macro returns a btex etex construct The MPstring returns the text as a METAPOST string between quotes The raw text can be fetched with MPtext startMPcode picture p p MPbetex 1 picture q q textext MPstring 2 J picture r r thelabel MPtext 3 origin for i p boundingbox p draw i withcolor 625red endfor for i q boundingbox q draw i withcolor 625yellow endfor for i r boundingbox r draw i withcolor 625white endfor currentpicture currentpicture scaled 2 draw origin withpen pencircle scaled 5 0mm withcolor white draw origin withpen pencircle scaled 2 5mm withcolor black draw boundingbox currentpicture withpen pencircle scaled imm dashed evenly stopMPcode Enhancing the layout If you watch closely you will notice that the first red alternative is positioned with the baseline on the origin startMPcode picture p p MPbetex 1 picture q q textext origin MPstring 2 aes picture r r thelabel origin MPtext 3 origin for i p boundingbox p draw i withcolor 625red endfor for i q boundingbox q draw i withcolor 625yellow endfor for i r boundingbox r draw i withcolor 625white endfor currentpicture currentpicture scaled 2 draw origin withpen pencircle scaled 5 0mm withcolor white
19. atom numeric expression expression numeric primary primary numeric tertiary tertiary numeric variable variable internal variable pair expression expression pair primary primary path expression expression path subexpression subexpression METAPOST syntax Page 569 Syntax diagrams Page 570 Syntax diagrams pen expression expression picture expression expression picture variable variable rgbcolor expression expression string expression expression suffix parameter parameter transform primary primary program statement list end statement list empty statement list statement statement empty equation assignment declaration macro definition compound pseudo procedure command METAPOST syntax compound begingroup statement list endgroup beginfig numeric expression statement list endfig equation expression right hand side assignment variable right hand side internal variable right hand side right and side expression equation assignment declaration type declaration list declaration list generic variable declaration list generic variable METAPOST syntax Page 571 Syntax diagrams generic variable Symbolic
20. bb rotatedaround origin 120 bb rotatedaround origin 240 cc reverse yy cycle rotatedaround origin 120 rotatedaround origin 240 fill fullcircle scaled radius withcolor white fill rr withcolor red fill cc withcolor white red R fill gg withcolor green fill mm withcolor white green fill bb withcolor blue fill yy withcolor white blue for i rr gg bb cc mm yy draw i withcolor 5white endfor currentpicture currentpicture xsized size enddef In determining the right intersection points you need to know where the path starts and in what direction it moves In case of doubt drawing the path as an arrow helps If you want to see the small paths used you A few applications need to comment the lines with the i11 s and uncomment the lines with draw s Due to the symmetry and the fact that we keep the figure centered around the origin we only need to calculate two paths since we can rotate them There are for sure more efficient ways to draw such a figure but this one demonstrates a few new tricks like grouping We use grouping here because we want to use mm to indicate the magenta path and mm normally means millimeter Within a group you can save variables These get their old values when the group is left With for we process multiple paths after each other In this case it hardly saves tokens but it looks more clever One of the more efficient methods is using the buildcycle mac
21. do_it 3 btex text etex do_it 4 btex header etex do_it 5 btex top etex In the horizontal direction we have edges margins and text There are left and right edges and margins which are swapped on even pages when you typeset a double sided document def do_it expr xx tt path p 11 y This is true only in a regular MmeTAPOST run In CONTEXT MKIV we follow a different route Page backgrounds Page 282 Setting up backgrounds p unitsquare xyscaled w xx h 1 shifted x xx y 1 label tt center p shifted 0 height h 1 2 enddef do_it 1 btex edge etex do_it 2 btex margin etex do_it 3 btex text etex do_it 4 btex margin etex do_it 5 btex edge etex Since we want the graphic to match the dimensions of the text area of the current page we have to make sure that the bounding box is adapted accordingly By this action the labels will fall outside the bounding box When we directly embed a graphic this works ok but when we start scaling and reusing due to the object reuse mechanism the graphic will be clipped to the bounding box setbounds currentpicture to unitsquare xyscaled width height In the following sections we will demonstrate how you can put graphics behind these 25 areas as well as behind the left and right page Setting up backgrounds One way of protecting a document for unwanted usage is to put an annoying word in the background If you like this you may try the followi
22. if intersection_found a a shifted 0 strutheight elee g a pat intersection_point lin Ra R b pat intersection_point lin shifted 0 strutdepth if intersection_found if sig Typesetting in METAPOST Page 427 Talking to Tex if xpart b gt xpart a a b shifted 0 strutdepth fi if xpart b lt xpart a a b shifted 0 strutdepth fi fag fik a enddef stopuseMPgraphic Instead of using meTAPOST s intersectionpoint macro we use one that comes with CONTgXT That way we don t get an error message when no point is found and can use a boolean flag to take further action Since we use a vardef all calculations are hidden and the a at the end is returned so that we can use this macro in an assignment The sig variable is used to distinguish between the beginning and end of a line the left and right subpath startuseMPgraphic text step path line pair 111 rrr for i topskip step baselineskip until vsize line ulcorner q urcorner q shifted 0 i 111 found_point line l true rrr found_point line r false stopuseMPgraphic Typesetting in METAPOST Page 428 Talking to Tex Here we divide the available space in lines The first line starts at strutheight from the top We can now finish our graphic by visualizing the lines Both the height and depth of the lines are shown startuseMPgraphic text line fill 11l rrr rrr shifted 0 strutheight 111 shif
23. p 212 4 q zi3 1 r z 4 1 s for i 1 upto 4 za E Eli ea os a a al 4 qlee atmal i A a z i 2 x i 2 y i 2 z i 3 x i 2 y i 2 y i 1 y i 2 x i 2 x i 1 z i 4 x i 1 y i 2 y i 1 y i 1 x i 2 x i 1 glu 0AE eA nl endfor z 0 whatever z 1 z 3 whatever z 2 z 4 pickup pencircle scaled 5pt content index reference Page 88 Clipping for i 1 upto 4 draw zi 1 zli 2 z i 3 zli 4 cycle draw z i 1 z i 3 draw z i 2 z i 4 if i lt 3 draw z i z i 2 dashed evenly fi endfor draw 1 0 1 1 0 1 zscaled unitvector z 1 z 0 10pt shifted z 0 endgroup enddef I think that we could argue quite some time about the readability of this code If you start from a sketch and the series of equations does a good job there is hardly any need for such improvements to the code On the other hand there are situations where the simplified reduced case can be extended more easily for instance to handle 10 points instead of 4 It all depends on how you want to spend your free hours Clipping For applications that do something with a drawing for instance Tpx embedding a graphic in a text flow it is important to know the dimensions of the graphic The maximum dimensions of a graphic are specified by its bounding box Welcome to MetaPost Page 89 Clipping A boundi
24. picture p numeric o path a b pair c p textext rt MPstring FunnyFrame o BodyFontSize a unitsquare xyscaled OverlayWidth OverlayHeight Enhancing the layout p p shifted 20 0verlayHeight ypart center p drawoptions withpen pencircle scaled 1pt withcolor 625red b a superellipsed 95 fill b withcolor 85white draw b b boundingbox p superellipsed 95 fill b withcolor 85white draw b draw p withcolor black setbounds currentpicture to a stopuseMPgraphic Zapf 3 Many people are just fascinated by their PC s tricks and think that a widely praised program called up on the screen will make everything automatic from now on There are quite some hard coded values in these graphics like the linewidths offsets and colors Some of these can be fetched from the framed environment either by using TeX macros or dimensions or by using their METAFUN counterparts In the following table we summarize both the available metarost variables and their Tpx counterparts They may be used interchangeably METAPOST Variable TeX command meaning OverlayWidth overlaywidth current width OverlayHeight overlayheight current height OverlayDepth overlayheight current depth often zero OverlayColor MPcolor overlaycolor background color content index reference OverlayLineWidth overlaylinewidth width of the frame OverlayLineColor MPcolor
25. x 15cm y 5cm location br externalfigure somecow pdf width 3cm setlayer BackLayer x 15cm y 5cm location t1 externalfigure somecow pdf width 1cm setlayer BackLayer x 15cm y 5cm location tr externalfigure somecow pdf width 2cm set layer BackLayer x 15cm y 5cm location c externalfigure somecow pdf width 3cm content index reference Page 267 More layers examples again demonstrate how we can influence the placement by assigning an anchor point to tn Here we also put the reference point in the lower left corner bottom This mechanism only works Nalso use height Figure 5 1 height 50pt startMPcode externalfigure somecow pdf xscaled 100bp yscaled 100bp rotated 25 stopMPcode One of the reasons for developing the layer mechanism was that we needed to slightly change the position of figures in the final stage of typesetting The previous pages demonstrate how one can position anything anywhere on the page but in the case of figures the position may depend on where the text ends up on the page Normally when you manipulate a document this way you are in the final stage of typesetting You may qualify this as desk top publishing without actually using a desktop setlayer BackLayer position yes location c voffset 5cm width 50pt Positional graphics Page 268 More layers The previous
26. 0 i StrutDepth cycle withcolor 85white draw p shifted 0 i withpen pencircle scaled 25pt withcolor 5white draw p shifted 0 i ExHeight withpen pencircle scaled 25pt withcolor 5white draw textext origin strut How are those penalty lines called in english I may not steal candies amp decimal n shifted 1 i shifted 0 StrutDepth endfor StopPage stopMPpage stop This code demonstrates the use of LineHeight ExHeight StrutHeight and StrutDepth We set the interline spacing to 1 5 so that we get a bit more loose layout The variables mentioned are set each time a graphic is processed and thereby match the current font settings Enhancing the layout Positional graphics In this chapter we will explore some of the more advanced but also conceptually more difficult graphic capabilities of CONTEXT It took quite a few experiments to find the right way to support these kind of graphics and you can be sure that in due time extensions will show up You can skip this chapter if you are no CONTEXT user The concept After Tex has read a paragraph of text it will try to break this paragraph into lines When this is done the result is flushed and after that Tex will check if a page should be split off As a result we can hardly predict how a document will come out Therefore when we want graphics to adapt themselves to this text we have to deal with this asynchronous feature of Tex in a rather advanced way
27. 625 red And indeed we get some drawing Functions Page 389 Drawing functions Page 390 Drawing functions Let s see what happens when we use less accuracy and a different connector draw ctxlua metapost metafun interpolate math sin x72 2 x math sqrt math abs x math pi 2 math pi 2 10 xysized 6cm 3cm withpen pencircle scaled 1mm withcolor 625 red Now we get Functions Page 391 Drawing functions Of course we could extend this LUA function with all kind of options and we might even do that when we need it Functions Typesetting in METAPOST It is said that a picture tells more than a thousand words So you might expect that text in graphics becomes superfluous Out of experience we can tell you that this is not the case In this chapter we explore the ways to add text to METAPOST graphics and let you choose whether or not to have it typeset by Tex The process You can let MeTAPOST process text that is typeset by TeX Such text is first embedded in the metarost file in the following way btex Some text to be typeset by TEX etex This returns a picture but only after meTAPosT has made sure that Tx has converted it into something useful This process of conversion is slightly system dependent and even a bit obscure Traditional Metarost calls a program that filters the btex etex commands next it calls Tex by passing the output routine in order to make sure that each piec
28. Page 222 One page graphics One page graphics An advantage of using CONTEXT to make your METAPOST graphics is you don t have to bother about specials font inclusion and all those nasty things that can spoil a good day An example of such a graphic is the file mfun 888 that resides on the computer of the author output pdftex copyright pragma ade readme readme pdf licence cc by nc sa setupcolors state start setupMPpage offset 1pt background color backgroundcolor gray definecolor gray s 625 definecolor red r 625 definecolor yellow r 625 g 625 startuseMPgraphic test fill fullsquare rotated 45 scaled 4cm withcolor MPcolor yellow stopuseMPgraphic content index reference Page 223 One page graphics starttext startMPpage includeMPgraphic test fill fullcircle scaled 3cm withcolor MPcolor red stopMPpage stoptext Given that CONTEXT is present on your system you can process this file with context mfun 888 You can define many graphics in one file Later you can include individual pages from the resulting PDF file in your document placefigure A silly figure demonstrating that stand alone graphics can be made externalfigure mfun 888 page 1 In this case the page 1 specification is not really needed You can scale and manipulate the figure in any way supported by the macro package that you use Embedded graphics Figure 3 8 A silly figure dem
29. The trick is in the last couple of lines In addition to the general enlarged operator we have 4 operators that enlarge a rectangle in a certain direction This means that we can define the original path using dimensions related to the layout and add bleed strips independently content index reference Page 307 Bleeding path p p fullsquare xyscaled 4cm icm path q q p leftenlarged 2mm topenlarged 2mm fill p withcolor transparent 1 5 625yellow fill q withcolor transparent 1 5 625yellow draw boundingbox currentpicture withcolor 625red This example demonstrates that when we enlarge a graphic the bounding box also gets larger Because this can interfere with the placement of such a graphic we need to make sure that the bleeding is there but not seen path p p fullsquare xyscaled 4cm 1cm path q q p leftenlarged 2mm topenlarged 2mm fill p withcolor transparent 1 5 625yellow fill q withcolor transparent 1 5 625yellow setbounds currentpicture to p draw boundingbox currentpicture withcolor 625red There are two more operators innerenlarged and outerenlarged These expand to either leftenlarged or rightenlarged depending on the page being left or right hand Page backgrounds Page 308 Interfacing to Tx Shapes symbols and buttons One can use METAPOST to define symbols and enhance buttons Here we introduce some of the gadgets that come with CONTEXT as well as explain h
30. Typesetting in METAPOST Page 399 T X text We also started fresh by resetting the drawing From now on each start command will add some more to this graphic The next macro is responsible for collecting the data Each element is passed on to Tex using the btex construct So METAPOST itself will call Tex def whatever 1 appendtoks 1 to MPtoks setbox MPbox hbox bfd the MPtoks startMPdrawing n n 1 len n the wd MPbox stopMPdrawing startMPdrawing pic n textext bfd setstrut strut 1 pic n pic n shifted llcorner pic n stopMPdrawing handletokens MetaPost is Fun with whatever We use the low level CONTEXT macro appendtoks to extend the token list MPtoks The handletokens macro passes each token character of MetaPost is Fun to the macro whatever The tokens are appended to the token register MPtoks already defined Then we typeset the content of MPtoks in MPbox also already defined The width of the box is passed to MeTAPosT and stored in len By default the content of the drawing is expanded which means that the macro is replaced by its current meaning so the current width ends up in the metarost file The next part of the drawing starting with btex puts the token in a picture This time we don t expand the drawing since we want to pass font information Here the suppresses expansion of btex bfd 1 etex The process is iterated by handletokens for each character
31. When passed to metarosr this code is encapsulated in its beginfig and endfig macros and thereby grouped But any change to a variable that is not explicitly saved migrates to the outer level In order to prevent all successive graphics to have butt d linecaps we have to change this line characteristic locally Because linecap is defined as an internal variable we have to use interim to overload its value Because u is a rather commonly used scratch variable we don t save its value Watch how we use u as the loop step In spite of what your eyes tell you this graphic only has two explicit color directives both being 50 black In the next example we will use some real colors In figure 13 3 the small squares in the center of each colored pair of big squares have the same shade but the way we perceive them are influenced by their surroundings Both sets of squares are defined using usable graphics The top squares are defined as startuseMPgraphic second includeMPgraphic first fill fullsquare scaled size withcolor topshade A few applications Figure 13 3 The simultaneous contrast effect fill fullsquare scaled delta withcolor centershade stopuseMPgraphic and the bottom squares are coded as startuseMPgraphic third includeMPgraphic first fill fullsquare scaled size withcolor bottomshade fill fullsquare scaled delta withcolor centershade stopuseMPgraphic A few applications Page 514 Fool yourself
32. as few s as possible When in doubt or when surprised by unexpected results use parentheses Arguments The metaAPost macro language is rather flexible in how you feed arguments to macros If you have only one argument the following definitions and calls are valid Welcome to MetaPost Page 62 Arguments def test expr a enddef test a test a def test expr a enddef test a test a A more complex definition is the following As you can see you can call the test macro in your favorite way def test expr a b expr c d enddef test a b c d test a b c d test a b c d test a b c d The type of the arguments is one of expr primary or suffix When fetching arguments METAPOST uses the type to determine how and what to grab A fourth type is text When no parenthesis are used a text argu ment grabs everything upto the next semicolon def test expr a text b enddef test a test a b You can use a text to grab arguments like withpen pencircle scaled 10 withcolor red Because text is so hungry you may occasionally need a two stage definition def test expr a dotext a enddef def dotest expr a text b enddef test a test ab Welcome to MetaPost This definition permits arguments without parenthesis which is something you want with commands like draw The vardef alternative behaves in a similar way It always provides grouping You
33. definecolor tred r 1 t 5 a exclusion definecolor tgreen g 1 t 5 a exclusion definecolor tblue b 1 t 5 a exclusion Both keys are needed You can define your own symbolic names using definetransparency myowndefault 1 The MPcolor macro passes a color from CONTEXT to METAPOST including the transparency specification definecolor tred r 1 t 5 a exclusion definecolor tgreen g 1 t 5 a exclusion definecolor tblue b 1 t 5 a exclusion Of course this also works well for CMYK colors content index reference definecolor tred c 1 k definecolor tgreen m 1 k definecolor tblue y 1 k Gray scales work as well definecolor ta s 9 t 7 a 11 definecolor tb s 7 t 7 a 11 definecolor tc s 5 t 7 a 11 We apply this to some text By using an overlay we can conveniently explore the difference in fonts draw textext color ta tf Hello scaled 5 draw textext color tb bf Hello scaled 5 draw textext color tc sl Hello scaled 5 Hello content index reference Clipping In this section we will use the graphic representation although simplified of a Dutch cow to demonstrate clipping Figure 8 2 A cow Since this cow is defined as a meTaPosT graphic we use the suffix mps instead of eps or a number although CONTEXT will recognize each as being METAPOST output The placement of the cow is defined as placefigure A cow externalfigure
34. framed The macros parwidth and parheight are automatically set to the current shape dimensions The normal result is shown in fig ure 10 3 startbuffer setupframed offset overlay align normal frame off Typesetting in METAPOST width parwidth height parheight startcombination 2 2 framed background test 1 getshapetext test 1 framed background test 2 getshapetext test 2 framed background test 3 getshapetext test 3 framed background test 4 getshapetext test 4 stopcombination stopbuffer By using a buffer we keep placefigure readable placefigure here fig shapes A continuous text typeset in a non standard shape spread over four areas and right alligned getbuffer The traced alternative is shown in figure 10 4 This one is defined as placefigure here fig traced shapes A continuous text typeset in a non standard shape spread over four areas tracing on startMPinclusions boolean trace_parshape trace_parshape true stopMPinclusions getbuffer content index reference Page 440 Libraries ap pearance of Donald Knuth has his a her work spent the past several Knuth s Tx typeset years working on a system al tng moen eo berme lowing him to control many as well known and available in many pects of the design of his forthcom countries around the world By contrast ing books from the typesetting and his METAFONT system for des
35. intersectionpoint reverse circleB draw_dot pointC label 1lft btex C etex pointC shifted 2w 0 draw_dot pointD label 1lft btex D etex pointD shifted 2w 0 enddef stopbuffer In placing the label we must make sure that the text runs free of the lines and curves Again move the stand_out macro just prior to draw_intersection macro so that this step is highlighted in the drawing color while prior steps are drawn in the default color in this case black startbuffer 3 start_everything draw_basics draw_circles stand_out draw_intersection stop_everything stopbuffer A few applications Page 524 Growing graphics The line drawn through points C and D will be the perpendicular bisector of the line segment connecting points A and B In the next step we will draw a line using the plain MeTAPOsT drawdblarrow macro that draws arrowheads at each end of a path startbuffer f def draw_bisector path lineCD lineCD origin origin shifted 2 distance 0 lineCD lineCD rotated 90 shifted 0 5 pointA pointB lineCD lineCD shifted 0 distance drawdblarrow lineCD enddef stopbuffer startbuffer 4 start_everything draw_basics draw_circles draw_intersection stand_out draw_bisector stop_everything stopbuffer A few applications Page 525 Growing graphics The following code draws the intersection of line C D and line segment A
36. linejoin beveled metapost variable inverted picture inverted currentpicture metafun macro n icture uncolored color currentpicture uncolored green metafun macro a lt content index reference icture softened numeric currentpicture softened 8 cw icture softened color currentpicture softened 7 8 9 metafun macro metafun macro rayed picture grayed currentpicture metafun macro content index reference label MetaFun origin metapost macro label top label top MetaFun origin metapost macro y LF un CI label bot label bot MetaFun origin metapost macro label lft label 1ft MetaFun origin metapost macro label rt MetaFun origin metapost macro Reference label ILft label 11 t MetaFun origin metapost macro label rt label 1rt MetaFun origin metapost macro label urt label urt MetaFun origin metapost macro label ulft label ulft MetaFun origin metapost macro btex text etex draw btex MetaTeX etex metapost primitive IMeta Tex content index reference textext string raphictext string Metal un Graphics loadfigure string number numeric J Page 647 Graphics draw textext MetaFun metafun macro graphictext MetaFun metafun macro loadfigure mycow mp number 1 scaled 25 metafun macro content index reference externalfigure string externalfig
37. participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if it is too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed butin my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest inte
38. predefined _circular _shade pathexpr numericexpr colorexpr color expr External figures are just files so the string passed as first argument needs to be a valid filename Additionally they need to be given dimensions content index reference Page 581 Left overs pseudo procedure externalfigure string expression transformer An external metarost graphic can be loaded by filename and figure number The normal transformations can be applied pseudo procedure loadfigure string expression figure number transformer figure number number numeric expression A graphic text is normally an outline representation of a snippet of text typeset by Tex This procedure has a couple of dedicated options pseudo procedure graphictext string expression transformer text option list regraphictext transformer text option list text option list empty text drawing option text option list METAPOST syntax text drawing option drawing option reversefill outlinefill withdrawcolor color expression withfillcolor color expression pseudo procedure resetgraphictextdirective graphictextdirective string expression internal variable gt graphictextformat METAPOST syntax Page 582 Left overs This document This document is produced in CONTgXT and can serve as an example of how to integrate METAPOST graphics into
39. randomized 5cm drawpath p drawpoints p drawpointlabels p draw point 2 25 of p withpen pencircle scaled 5mm withcolor 625red ee 1 To this we add two more operators on and along With on you get the point at the supplied distance from point 0 with along you get the point at the fraction of the length of the path path p q r p fullsquare xyscaled 2cm 2cm randomized 5cm q p shifted 3cm 0 r q shifted 3cm 0 drawpath p drawpoints p drawpointlabels p drawpath q drawpoints q drawpointlabels q drawpath r drawpoints r drawpointlabels r pickup pencircle scaled 5mm draw point 2 25 of p withcolor 625red draw point 2 50cm on q withcolor 625yellow draw point 45 along r withcolor 625white Welcome to MetaPost Beware the length of a path is the number of points minus one The shapes below are constructed from 5 points and a length of 4 If you want the length as dimension you should use arclength il We will now play a bit with simple lines With cutends you can indeed cut off the ends of a curve The specification is a dimension path p p Ocm 0cm 4cm 1cm path q q 5cm 0cm right 9cm 1cm drawpath p drawpoints p drawpath q drawpoints q p p cutends 5cm q q cutends 5cm drawpathoptions withpen pencircle scaled 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4pt withcolor 625red drawpath p
40. se reduce boil down choose categorize catalog classify list abstract scan look into e isolate discriminate distinguish screen pigeonhole pick over sort integrate blend spect filter lump skip smooth chunk average approximate cluster aggregate outline sum arize itemize review dip into flip through browse glance into leaf through skim refine bnumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the us I came to the conclusion that the designer of a new system must not only be the implementen hnd first large scale user the designer should also write the first user manual e separation of any of these four components would have hurt TX significantly If I had no ipated fully in all these activities literally hundreds of improvements would never have beer ade because I would never have thought of them or perceived why they were important ald Knuth has spent the past several years working on a system allowing him to control many bspects of the design of his forthcoming books from the typesetting and layout down to the ver apes of the letters Seldom has an author had anything remotely like this power to control th al appearance of his or her work Knuth s TIX typesetting system has become well known an ailable in many countries around the world By contrast his METAFONT system for designing ies of typefaces has not become as well known or available his article The Conc
41. setMPpositiongraphic G 1 mypos circle setMPpositiongraphic G 2 mypos circle setMPpositiongraphic G 3 mypos circle setMPpositiongraphic G 4 mypos circle stoppositionoverlay startpositionoverlay foregraphics setMPpositiongraphic G 1 mypos line to G 2 setMPpositiongraphic G 2 mypos line to G 3 setMPpositiongraphic G 3 mypos line to G 4 stoppositionoverlay First we have defined an erlay This We define four small ircles Erese ar a in the background they don t cover the text while the lines do The previous paragraph was typeset by saying First we have defined an hpos G 1 overlay This overlay can be attached to some overlay layer like in our case the hpos G 2 page We define four small hpos G 3 circles These are drawn as soon as the page overlay is typeset Because they are located in the background they don t cover the hpos G 4 text while the lines do The previous paragraph was typeset by saying Positional graphics As said the circles are on the background layer but the lines are not They are positioned on top of the text This is a direct result of the definition of the page background defineoverlay foregraphics positionoverlay foregraphics defineoverlay backgraphics positionoverlay backgraphics setupbackgrounds page background backgraphics foreground foregraphics In this definition the predefined overlay foreground inserts the pag
42. setupalign broad middle veryraggedcenter setupalign broad left veryraggedleft The broad increases the raggedness We defined three different graphics a b and c because we want some to be unique which saves some processing Of course we don t reuse the random graphics In the definition of processword we have to use noindent because otherwise Tx will put each graphic on a line of its own Watch the space at the end of the macro Graphics and macros Because TgxX s typographic engine and metarost s graphic engine are separated interfacing between them is not as natural as you may expect In CONTEXT we have tried to integrate them as much as possible but using the interface is not always as convenient as it should be What method you follow depends on the problem at hand The official MeTaPost way to embed Tpx code into graphics is to use btex etex As soon as CONTEXT writes the graphic data to the intermediate metarost file it looks for these commands When it has encountered Enhancing the layout an etex CONTEXT will make sure that the text that is to be typeset by Tex is not expanded This is what you may expect because when you would embed those commands in a stand alone graphic they would also not be expanded if only because metarost does not know Tpx With expansion we mean that TeX commands are replaced by their meaning which can be quite extensive Users of CONTEXT MKIV can skip the next par
43. the following for loop will be no surprise draw origin for i 0 step 10 until 100 down i 0 endfor This gives the zig zag curve Welcome to MetaPost Page 57 Macros fi Gpealiealse inl a0 B endfor Here we remain in the loop until we have 10 points placed We use an array to keep track of placed points The METAPOST Macro uniformdeviate n returns a random number between 0 and n and the round command is used to move the result toward the nearest integer The unknown primitive allows us to test if the array element already exists otherwise we exit the conditional This saves a bit of computational time as each point is drawn and indexed only once The loop terminator exitif and its companion exitunless can be used in for forsuffixes and forever Macros In the previous section we introduced upto Actually this is not part of the built in syntax but a sort of shortcut defined by def upto step 1 until enddef Welcome to MetaPost Page 58 Macros You just saw a macro definition where upto is the name of the macro The counterpart of upto is downto Whenever you use upto it is replaced by step 1 until This replacement is called expansion There are several types of macros A primary macro is used to define your own operators For example primarydef p doublescaled s p xscaled s 2 yscaled s 2 enddef Once defined the doublescaled macro is implemented as in the following example draw somepath
44. ysin r x sin r y cos r Welcome to MetaPost Page 21 Transformations The previously mentioned rotatedaround is not a primitive but a macro defined in terms of shifts and rota tions Another transformation macro is mirroring or in MeTAPosT terminology reflectedabout The reflection axis is specified by a pair of points For example in the graphic above we used the following command to reflect the square about a line through the given points p reflectedabout 2 4cm 5 2 4cm 3cm The line about which the path is mirrored Mirroring does not have to be parallel to an axis p reflectedabout 2 4cm 5 2 6cm 3cm The rectangle now becomes Welcome to MetaPost Page 22 Transformations The table also mentions zscaled A zscaled specification takes a vector as argument p zscaled 2 5 The result looks like a combination of scaling and rotation and conforms to the formula in the previous table Welcome to MetaPost Transformations can be defined in terms of a transform matrix Such a matrix is stored in a transform variable For example transform t t identity scaled 2cm shifted 4cm 1icm We use the associated keyword transformed to apply this matrix to a path or picture p transformed t In this example we ve taken the identity matrix as starting point but you can use any predefined transforma tion The identity matrix is defined in such a way that it scales by a factor of one
45. z32 dotlabel urt Z_ 33 z33 dotlabel urt Z_ 34 z34 dotlabel irt Z_ 41 z41 dotlabel urt Z_ 42 z42 dotlabel 11ft Z_ 43 z43 dotlabel 1rt Z_ 44 z44 dotlabel urt Z_ 0 z0 dotlabel 1lft Z_ 1 z1 dotlabel top Z_ 2 z2 dotlabel rt Z_ 3 z3 dotlabel bot Z_ 4 z4 enddef stopMPdefinitions Watch out as we are in CONTEXT we can pass regular TeX code to the label macro In a standalone METAPOST run you d have to use the btex variant We are going to draw a lot of pictures so we define an extra macro This time we hard code some values The fractions i and j are responsible for the visual iteration process while s determines the labels We pass these variables to the graphic using an extra argument When you define the useable graphic you need to tell what variables it can expect startuseMPgraphic one i j st draw_problem 400pt 400pt 300pt 600pt MPvar i 300pt 600pt 550pt 800pt MPvar j 400pt 400pt 550pt 500pt MPvar s Welcome to MetaPost D8 stopuseMPgraphic Of course we could have used a loop construct here but defining auxiliary macros probably takes more time than simply calling the drawing macro directly The results are shown on a separate page figure 1 3 We will use a helper macro that saves us typing def MyTest 1 2 scale width 25 textwidth useMPgraphic solvers one i 1
46. 25cm amp amp amp amp amp amp A few more details filled false stroked true textual false clipped false bounded false cycle true In this code snippet condition is a macro that takes care of translating a boolean value into a string like decimal does with a numeric value def condition primary b alse Joy e Therese ile g Wakely fi enddef Clip paths and bounding boxes are kind of special in the sense that they can obscure components The fol lowing examples demonstrate this In case of a clip path or bounding box the pathpart operator returns this path In any case that asking for a value does not make sense a clipping path for instance has no color a zero null value is returned draw fullcircle withpen pencircle scaled 3mm clip currentpicture to fullcircle setbounds currentpicture to fullcircle n 1 length 1 stroked false clipped true bounded false A few more details Page 187 Analyzing pictures draw fullcircle withpen pencircle scaled 3mm setbounds currentpicture to fullcircle clip currentpicture to fullcircle 1 length 1 stroked false clipped false bounded true clip currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm setbounds currentpicture to fullcircle 1 length 0 stroked false clipped true bounded false 2 length 1 stroked true clipped false bounded false clip currentpicture to
47. 350 libraries 318 435 positioning 254 standalone 211 symbols 322 variables 316 grids 374 i inclusions 220 inflection 146 interfacing 308 interims 199 internals 199 J joining 69 1 labels 396 476 language 560 layers 257 262 layout 274 455 loops 55 m macros 57 arguments 61 Page 653 Distributions metafun 558 o outlines 363 overlays 226 282 stack 287 P paths 9 23 634 cutting 108 joining 69 pens 64 pictures 115 analyzing 182 points 634 positioning 254 processing 6 200 r randomization 310 rotation 41 running 6 200 s scaling 131 shading 325 shifting 131 styles 455 symbols 322 syntax 560 t tension 146 text 74 270 392 397 649 outlines 363 Page 654 Distributions transformations 17 163 634 transparency 334 u units 128 v variables 51 316 For them I owe much inspiration to both my parents My mother Jannie constantly demonstrates me that computer graphics will never improve nature She also converted one of my first METAPOST graphics into a patchwork that will remind me forever that handcraft is more vivid than computer artwork My father Hein has spent a great deal of his life teaching math and I m sure he would have loved metarost I inherited his love for books I therefore dedicate this document to them Colofon This manual is typeset with CONTEXT MKIV No special tricks are used and everything you see in here is
48. 9 1 Quick and dirty grid paper Functions Page 379 Drawing functions definitions stoptext Drawing functions Today there are powerful tools to draw functions on grids but for simple functions you can comfortably use METAPOST Let s first draw a simple log linear grid drawoptions withpen pencircle scaled 25pt withcolor 5white draw hlingrid 0 20 2 20cm 10cm draw vloggrid O 10 5 10cm 20cm drawoptions withpen pencircle scaled 50pt draw hlingrid 0 20 1 20cm 10cm draw vloggrid O 10 1 10cm 20cm To this grid we add some labels fmt_pictures false use TeX as formatting engine textextoffset ExHeight a variable set by ConTeXt draw hlintext 1ft 0 20 5 20cm 3e draw vlogtext bot 0 10 9 10cm 3e Functions Page 380 Drawing functions The arguments to the text placement macros are similar to the ones for drawing the axes Here we provide a format string hlintext Min Max Step Length Format vlintext Min Max Step Length Format hlogtext Min Max Step Length Format vlogtext Min Max Step Length Format When drawing a smooth function related curve you need to provide enough sample points The function macro will generate them for you but you need to make sure that for instance the maximum and minimum values are part of the generated series of points Also a smooth curve is not always the right curve Therefore we provide t
49. An example of a simple rectangular path is Tn the next examples we use the debugging features discussed in chapter 11 to visualize the points paths and bounding boxes Welcome to MetaPost Page 11 Paths This path is constructed out of four points Such a path has both a beginning and end and runs in a certain direction Welcome to MetaPost Page 12 Paths When we close this path and in a moment we will see how to do this the path looks like Welcome to MetaPost Page 13 Paths iH The open path is defined as 1cem icm 1 5cm 1 5cm 2cm 0cm The double period connector tells metapost that we want to connect the lines by a smooth curve If you want to connect points with straight line segments you should use Closing the path is done by connecting the first and last point using the cycle command 1cem icm 1 5cm 1 5cm 2cm 0cm cycle Feel free to use or at any point in your path 1cm 1cm 1 5cm 1 5cm 2cm 0cm cycle This path when drawn looks like this Welcome to MetaPost Page 14 Paths a As you can see in some of the previous examples mETAPOST is capable of drawing a smooth curve through the three points that make up the path We will now examine how this is done ip The six small points are the so called control points These points pull their parent point in a certain direction The further away such a point is the stronger the pull Each po
50. In CONTEXT colors are called by name content index reference Page 215 Communicating color The next definitions demonstrate that we can define a color using different color models RGB or CMYK De pending on the configuration CONTEXT will convert one color system to the other RGB to CMYK or vice versa The full repertoire of color components that can be set is as follows definecolor color one r 1 g 2 b 3 definecolor color two c 4 m 5 y 6 k 7 definecolor color three s 8 The numbers are limited to the range 0 1 and represent percentages Black is represented by definecolor black 1 r 0 g 0 b 0 definecolor black 2 c 0 m 0 y 0 k 1 definecolor black 3 s 0 Predefined colors are passed to METAPOST graphics via the MPcolor First we define some colors definecolor darkyellow y 625 a CMYK color definecolor darkred r 625 a RGB color definecolor darkgray s 625 a gray scale These are the colors we used in this document The next example uses two of them startuseMPgraphic color demo pickup pencircle scaled 1mm path p p fullcircle xscaled 10cm yscaled icm fill p withcolor MPcolor darkgray draw p withcolor MPcolor darkred Embedded graphics stopuseMPgraphic useMPgraphic color demo The previous example uses a pure RGB red shade combined with a gray fill i O OOO Since meTAPOST does not support the CMYK color space and native gray scal
51. It may be clear now that we need some positional information in order to provide features like the ones shown here The fact that we will act upon in a second pass simplifies the task although it forces us to store the positional information between runs in some place This may look uncomfortable at first sight but it also enables us to store some additional information Now why is that needed content index reference Page 256 The concept A position has no dimensions it s just a place somewhere on the page In order to do tricks like those shown here we also need to know the height and depth of lines at a specific point as well as the width of the box es we re dealing with In the encircled examples the dimensions of the box following the positional node are stored along with the position In the background example we store the current height and depth of the strut an imaginary character with maximum height and depth but no width along with the current text width In order to process the graphics we tag each point with a name so that we can attach actions to those points In fact they become trigger points As we will demonstrate we also need to store the current page number This brings the data stored with a point to lt identifier gt lt pagenumber gt lt x gt lt y gt lt width gt lt height gt lt depth gt The page number is needed in order to let the graphics engine determine boundary conditions Backgrounds like those sh
52. PSTOEDIT code is due to Scott Pakin Some of the graphics that we use in this section are produced that way For us the next call works well but the exact call may differ per version or platform pstoedit ssp dt f mpost yourfile ps newfile mp We have converted the Dutch cow that shows up in many CONTEXT documents into MeTAPOST using this pro gram The resulting metarost file encapsulates the cow in metarost figure 1 beginfig 1 Of course you can process this file like any other but more interesting is to use this code in an indirect way loadfigure mycow mp number 1 scaled 5 This call will load figure 1 from the specified metarost file in such a way that there is no interference with the current encapsulating figure Special effects Because this graphic is the result from a conversion there are only paths If you want to import a more complex graphic you need to make sure that the variables used in there do not conflict with the one currently in use METAPOST is good in drawing vector graphics but lacks natural support for bitmaps but the next macro offers a way out This macro permits you to include graphics in PNG PDF and JPG format or more precise those formats supported by PDFIEX externalfigure hacker png scaled 5cm shifted 6cm 0 externalfigure hacker png scaled 5cm slanted 5 You can apply the usual transformations but only those applied directly will be taken into account This means that you
53. Paths unitsquare metapost variable fulldiamond metafun variable unitdiamond metafun variable halfcircle a uartercircle N llcircle Reference halfcircle metapost variable quartercircle metapost variable licircle metafun variable ircircle metafun variable Reference Page 598 Paths urcircle metafun variable ulcircle metafun variable tcircle metafun variable bcircle metafun variable d D lltriangle N lrtriangle Reference Page 599 Paths lcircle metafun variable rcircle metafun variable lltriangle metafun variable lrtriangle metafun variable urtriangle Reference urtriangle metafun variable ultriangle metafun variable flex G ORO Pi Gla CTO metapost macro Superellsletpse Clem s C 5 1 Onm gt Por eerie metapost macro ath smoothed numeric pair ath cornered numeric pair a ath superellipsed numeric oe Page 601 Paths unitsquare scaled 1 5 smoothed 2 metafun macro lltriangle scaled 1 5 cornered 2 metafun macro unitsquare scaled 1 5 superellipsed 75 metafun macro content index reference ath randomized numeric pair ath squeezed numeric pair Lt Reference Page 602 Paths unitsquare scaled 1 5 randomized 2 2 metafun macro unitsquare scaled 1 5 squeezed 2 1 metafun macro Page 603 Paths punked path punked unitcircle sc
54. Reference Ilcorner path Ircorner path urcorner path Reference Page 623 Transformations licorner fullcircle metapost primitive ircorner fullcircle metapost primitive urcorner fullcircle metapost primitive ulcorner path center path boundingbox path Reference Page 624 Transformations ulcorner fullcircle metapost primitive center fullcircle metapost macro boundingbox fullcircle metafun macro innerboundingbox path outerboundingbox path N bottomboundary path V4 Reference Page 625 Transformations innerboundingbox fullcircle metafun macro outerboundingbox fullcircle metafun macro bottomboundary fullcircle metafun macro leftboundary path Va N NSA topboundary path rightboundary path Reference leftboundary fullcircle metafun macro topboundary fullcircle metafun macro rightboundary fullcircle metafun macro bbwidth path draw textext decimal bbwidth fullcircle xscaled 100 yscaled 200 metafun macro draw textext decimal bbheight fullcircle xscaled 100 yscaled 200 metafun macro ath picture xsized numeric currentpicture xsized 5cm metafun macro ath picture ysized numeric currentpicture ysized 2cm metafun macro Reference ath picture xysized numeric Points top pair Q bot pair D A Reference Page 628 Points currentpicture xysized 3cm 2cm m
55. Tex In this appendix we will discuss some details of producing this document We did not use any special tricks so most of the examples you have seen were coded just as shown We used buffers to ensure that the code used to produce the accompanying graphic is identical to the typeset code in the document Here is an example startbuffer dummy draw fullcircle xscaled 3cm yscaled 2cm rotatedaround origin 30 withcolor 625red stopbuffer Instead of using getbuffer we used the following command startlinecorrection blank processMPbuf fer dummy stoplinecorrection The line correction commands take care of proper spacing around the graphic If you want to process more buffers at once you can pass their names as a comma separated list This document exit lt dd gt gt Alternatively we could have said startuseMPgraphic dummy draw fullcircle xscaled 3cm yscaled 2cm rotatedaround origin 30 withcolor 625red stopuseMPgraphic When including this graphic we again take care of spacing startlinecorrection blank useMPgraphic dummy stoplinecorrection The first version of this manual was produced with PDFTsx and calls out to metaPosT Because the number of graphics is large we processed that version using the automp directive using TEXEXEC And even then runtime was so unconveniently long that updating this manual became less and less fun The current version is produced with LUATgX and CON
56. The advantage of using symbols is that you can redefine them depending on the situation So definesymbol yes em Yes creates a symbol that lets symbol yes expand into Yes Since nearly anything can be a symbol we can also say definesymbol yes mathematics star or even the already defined symbol x by saying definesymbol yes symbol star It may be clear that we can use a graphic as well def metabutt onsymbol 1 uniqueMPgraphic meta button type 1 definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu definesymbol menu left metabuttonsymbol 101 right metabuttonsymbol 102 list metabuttonsymbol 103 index metabuttonsymbo1 104 person metabuttonsymbol1 105 stop metabuttonsymbo1 106 Shapes symbols and buttons Page 323 Symbol collections definesymbol menu info metabuttonsymbo1 107 definesymbol menu down metabuttonsymbol1 108 definesymbol menu up metabuttonsymbol 109 definesymbol menu print metabuttonsymbol 110 Since we have collected some nice buttons in a meTarost file already we can use a rather simple definition startuniqueMPgraphic meta button type size linecolor fillcolor if unknown context_butt input mp butt fi some_button MPvar type MPvar size MPvar linecolor MPvar fillcolor stopuniqueMPgraphic This leaves a few settings setu
57. This macro is used in the following manner path mypath mypath randomscaledpath unitsquare 4cm Note that we send randomscaledpath a path unitsquare and a scaling factor 4cm The macro returns a scaled path which is then stored in the path variable mypath The following argument types are accepted Welcome to MetaPost Page 60 Macros expr something that can be assigned to a variable text arbitrary MeTAPOST code ending with a suffix a variable bound to another variable An expression is passed by value This means that in the body of the macro a copy is used and the original is left untouched On the other hand any change to a variable passed as suffix is also applied to the original Local variables must be handled in a special manner since they may conflict with variables used elsewhere This is because all variables are global by default The way out of this problem is using grouping in combina tion with saving variables The use of grouping is not restricted to macros and may be used anywhere in your code Variables saved and declared in a group are local to that group Once the group is exited the variables cease to exist vardef randomscaledpath expr p s begingroup save r numeric r r round 1 uniformdeviate 4 p xscaled s r yscaled s r endgroup enddef In this particular case we could have omitted the grouping since vardef macros are always grouped auto matically Therefore we
58. a bit different def anglebetween expr endofa endofb common length unitvector endofa common endofa common rotated 90 unitvector endofb common scaled length shifted common enddef As you can see we compensate for the origin of both vectors This macro is called with a few more parameters We need to pass the length since we want to add the shift to the macro and the shift takes place after the scaling A few applications Marking angles pairkan 1 3 2 Oe eo E e e eE eem drawarrow c a drawarrow c b drawarrow anglebetween a b c icm withcolor 625red That the results are indeed correct is demonstrated by the output of following example However when we swap the points we get This means that instead of rotating over 90 degrees we have to rotate over 90 or 270 degrees That way the arrow will also point in the other direction There are undoubtedly more ways to determine the direction but the following method also demonstrates the use of turningnumber which reports the direction of a path For this purpose we compose a dummy cyclic path A few applications Page 491 Marking angles vardef anglebetween expr endofa endofb common length save tn tn turningnumber common endofa endofb cycle show tn unitvector endofa common endofa common rotated tn 90 unitvector endofb common scaled length shifted common enddef Because we use an intermediate variable ju
59. a macro We want to feed the angle between the paths but also the connecting path So we have to pass a path but unfortunately we don t have direct access to the points By splitting the argument definition we can pass an expression first and a wildcard argument next startuseMPgraphic gamble def Gamble expr rot text track path a a fullcircle scaled 3cm path b b fullcircle scaled 2cm rotated rot pair aa aa point O0 of a pair bb bb point O of b path ab ab track draw withpen pencircle scaled imm withcolor 625red draw withpen pencircle scaled imm withcolor 625yellow draw withpen pencircle scaled 2mm content index reference Page 554 Killing time draw bb withpen pencircle scaled 2mm drawarrow ab withpen pencircle scaled 1mm withcolor 625white setbounds currentpicture to boundingbox a enlarged 2mm draw boundingbox currentpicture withpen pencircle scaled 25mm enddef stopuseMPgraphic Because at this distance nobody will bother us with the thickness of the pen and colors we code them the hard way We create our own universe by setting a fixed boundingbox We leave the Earth in the most popular way straight upwards and after a few cycles we leave it parallel to the surface The path drawn reminds much of the trajectories shown in popular magazines startMPcode includeMPgraphic gamble Gamble 120 aa 0 1 bb stopMPcode A few applications
60. amp textpart p 4cm 0 25cm label rt fontpart amp fontpart p 4cm 0 25cm pu textpart MetaFun et fontpart rm lmri0 We use normalinfont instead of infont because in METAFUN this operator is overloaded and follows another route for including text If we re dealing with a path the transformations have ended up in the path specification If we have a text picture we can explicitly ask for the transform components label rt xpart amp decimal xpart p 4cm 1 25cm label rt ypart amp decimal ypart p 4cm 0 75cm label rt xxpart amp decimal xxpart p 4cm 0 25cm label rt xypart amp decimal xypart p 4cm 0 25cm label rt yxpart amp decimal yxpart p 4cm 0 75cm label rt yypart amp decimal yypart p 4cm 1 25cm A few more details Analyzing pictures xpart 0O ypart 25 93834 pur xxpart 2 23206 met 2A xypart 0 13397 yxpart 1 yypart 1 73206 We will now define the inverted macro using these primitives Because we have to return a picture we cannot use draw and fi11 but need to use the low level operators Because a picture can consist of more than one path we need a temporary picture pp vardef inverted expr p save pp picture pp pp nullpicture for i within p addto pp if stroked i or filled i if filled i contour else doublepath fi pathpart i dashed dashpart i withpen penpart i elise also i fi withcolor white redpart i gre
61. available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font odd Figure 6 2 A background with combined areas Page backgrounds Page 292 Crossing borders In figure 6 2 you see two pages odd and even with a background spanning the outer margin and the text area You can access an area in two ways The area itself is available as Area StartPage fill Area Text Text withcolor 85white StopPage If you use an area this way you will notice that it is not positioned at the right place An Area is just a rectangle If you want a positioned area you should use the Field array StartPage fill Field Text Text withcolor 85white StopPage The location of an area is available in
62. b g buildcycle buildcycle b reverse g r rr gg transformed t bb rr transformed t yy cc transformed t mm yy transformed t fill fullcircle scaled radius withcolor white fill rr withcolor red fill cc withcolor white red 7 fill gg withcolor green fill mm withcolor white green fill bb withcolor blue fill yy withcolor white blue for i rr gg bb cc mm yy draw i withcolor 5white endfor currentpicture currentpicture xsized size enddef A few applications This rather nice circle is defined as colorcircle 4cm 4 6 8 8 4 6 6 8 4 The final implementation which is part of METAFUN is slightly more efficient vardef colorcircle expr size red green blue saver 2 DCs lly W 5 Save msadausm path r g b c m y Ww numeric radius radius 5cm pickup pencircle scaled radius 25 transform t t identity rotatedaround origin 120 r fullcircle rotated 90 scaled radius shifted 0 radius 4 rotatedaround origin 135 A few applications Page 506 Color circles Page 507 Color circles r transformed t g b transformed t buildcycle subpath 1 7 of g subpath 1 7 of b c transformed t m y transformed t buildcycle subpath 3 5 of r subpath 3 5 of g subpath 3 5 of b pushcurrentpicture fill r withcolor red fill g withcolor green fill b withcolor blue fill c withcolor white red fill m withcolor white
63. circle By setting autoarrows we make sure that the arrowheads are scaled proportionally to the linewidth of 1 mm A few applications Page 488 Marking angles An application of this macro is drawing the angle between two lines In the MeTAPOsT manual you can find two macros for drawing angles mark_angle and mark_rt_angle You may want to take a look at their definitions before we start developing our own alternatives The previous graphic demonstrates what we want to accomplish a circular curve indicating the angle between two straight lines The lines and curve are drawn with the code pair a b a 2cm icm b 3cm 1cm drawarrow origin a drawarrow origin b drawarrow anglebetween a b scaled 1cm withcolor 625red where anglebetween is defined as A few applications Page 489 Marking angles def anglebetween expr a b Cunitvector a a rotated 90 unitvector b enddef Both unitvectors return just a point on the line positioned 1 unit later scaled to 1cm from the origin We connect these points by a curve that starts in the direction at the first point If we omit the a rotated 90 direction specifier we get These definitions of anglebetween are far from perfect If we don t start in the origin we get the curve in the wrong place and when we swap both points we get the wrong curve The solution for the displacement is given in the MeTAaPosT manual and looks like this we package the macro
64. color of the frame BaseLineSkip the baselineskip main line distance LineHeight the baselineskip idem BodyFontSize the bodyfontsize font size of the running text StrutHeight strutheight space above the baseline StrutDepth strutdepth space below the baseline ExHeight lex height of an x EmWidth 1em width of an m dash startuseMPgraphic FunnyFrame picture p numeric o path a b pair c p textext rt MPstring FunnyFrame o BodyFontSize a unitsquare xyscaled OverlayWidth OverlayHeight p p shifted 20 0verlayHeight ypart center p pickup pencircle scaled OverlayLineWidth b a superellipsed 95 fill b withcolor OverlayColor draw b withcolor OverlayLineColor b boundingbox p superellipsed 95 fill b withcolor OverlayColor draw b withcolor OverlayLineColor draw p withcolor black setbounds currentpicture to a stopuseMPgraphic Enhancing the layout Many people are just fascinated by their PC s tricks and think that a widely praised program called up on the screen will make everything automatic from now on We used the following command to pass the settings setupframedtexts FunnyText backgroundcolor lightgray framecolor darkred rulethickness 2pt offset bodyfontsize before blank big medium after blank big width textwidth In a real implementation we should also take care of some additional spacing before the text which is why we have added more s
65. content index reference ath xyscaled pair ath shifted pair O o ath leftenlarged numeric Reference Page 611 Transformations fullcircle xyscaled 2 25 metapost primitive Luliliciecilenshat ced 25 metapost primitive fullsquare leftenlarged 25 metafun macro Page 612 Transformations ath topenlarged numeric fullsquare topenlarged 25 metafun macro fullsquare rightenlarged 25 metafun macro fullsquare bottomenlarged 25 metafun macro ath enlarged numeric ath enlarged pair Reference Page 613 Transformations fullcircle enlarged 725 metafun macro fullcircle enlarged 1 25 metafun macro ath llenlarged numeric ath lrenlarged numeric ath urenlarged numeric Reference Page 614 Transformations fullcircle llenlarged 25 metafun macro fullcircle lrenlarged 25 metafun macro fullcircle urenlarged 25 metafun macro Page 615 Transformations path ulenlarged numeric fullcircle ulenlarged 25 metafun macro fullcircle llenlarged 1 metafun macro path lrenlarged pair fullcircle lrenlarged 1 25 metafun macro Reference ath urenlarged pair ath ulenlarged pair ath Ilmoved numeric Reference Page 616 Transformations fullcircle urenlarged 1 25 metafun macro fullcircle ulenlarged 1 25 metafun macro fullcircle llmoved 25 metafun macro ath Irmoved numeric fullcircle lrmoved 25 metafun m
66. could have defined the macro as vardef randomscaledpath expr p s save r numeric r r round 1 uniformdeviate 4 Welcome to MetaPost Page 61 Arguments p xscaled s r yscaled s r enddef The command save r declares that the variable r is local to the macro Thus any changes to the new numeric variable r are local and will not interfere with a variable r defined outside the macro This is important to understand as variables outside the macro are global and accessible to the code within the body of the macro Macro definitions may be nested but since most MeTarost code is relatively simple it is seldom needed Nest ing is discouraged as it makes your code less readable Besides def and vardef meTAPost also provides the classifiers primarydef secondarydef and tertiarydef You can use these classifiers to define macros like those provided by metarost itself primarydef x mod cece Gimelelent 5 secondarydef p intersectionpoint q enddef tertiarydef p softjoin q coc Sumilslest 5 A primary macro acts like the binary operators or scaled and shifted Secondary macros are like and logical or and take less precedence The tertiary operators like lt or the path and string concatenation operator amp have tertiary macros as companions More details can be found in the MeTAFONT book When it comes to taking precedence MeTAPOST tries to be as natural as possible in the sense that you need to provide
67. dimensions and colors The graphic itself is not that spectacular We use amp because we don t want smooth connections defineblank EnglishRule medium def EnglishRule startlinecorrection EnglishRule setlocalhsize noindent reuseMPgraphic EnglishRule stoplinecorrection When setting the variables we used localhsize This variable is set by setlocalhsize We need to use noindent a rather familiar TeX primitive that we use here to start a non indented paragraph being the graphic The line correction is needed to get the spacing around the rule graphic right We pass a blank skip identifier that is mapped to a convenient medium skip content index reference Page 310 Random graphics Why is this called an English line startnarrower EnglishRule Is it because they cannot draw a straight one This could be true after a few strong beers but then how do Germans draw a line EnglishRule stopnarrower As expected the rule adapts itself to the current width of the text The height of the rule in the middle matches the height of a character with no ascenders and descenders Why is this called an English line eee Is it because they cannot draw a straight one This could be true after a few strong beers but then how do Germans draw a line eee Random graphics Given enough time and paper we can probably give you some Shapes symbols and buttons LHI IHT IHI LHT LH IHT LY LT LHI HHT LHA
68. draw origin withpen pencircle scaled 2 5mm withcolor black draw boundingbox currentpicture withpen pencircle scaled 1mm dashed evenly stopMPcode This draws Enhancing the layout Page 244 Graphics and macros This picture demonstrates that we can also position textext s and label s on the baseline For this purpose the repertoire of positioning directives top 1ft etc is extended with an origin directive Another extra positioning directive is raw This one does not do any positioning at all picture q q textext origin MPstring 2 I picture r r thelabel origin MPtext 3 origin We will now apply this knowledge of text inclusion in graphics to a more advanced example The next defin itions are the answer to a question on the CONTEXT mailinglist with regards to framed texts with titles Zapf 1 Coming back to the use of typefaces in electronic publishing many of the new typographers receive their knowledge and information about the rules of typography from books from computer magazines or the instruction manuals which they get with the purchase of a PC or software In this example the title is positioned on top of the frame Title and text are entered as FrameTitle Zapf 1 StartFrame Coming back to the use of typefaces in electronic content index reference publishing many of the new typographers receive their knowledge and information abou
69. euro_v_delta euro_v_delta euro_width 4 save outer_circle inner_circle hor_bar right_line right_slant top_slant bot_slant euro_circle euro_topbar euro_botbar path outer_circle inner_circle hor_bar right_line right_slant top_slant bot_slant euro_circle euro_topbar euro_botbar outer_circle fullcircle scaled euro_radius A few applications inner_circle fullcircle scaled euro_radius euro_width if trace_euro for i outer_circle inner_circle draw i withpen pencircle scaled ipt withcolor 5white endfor fi right_line lrcorner outer_circle urcorner outer_circle shifted euro_r_offset 0 outer_circle outer_circle cutbefore right_line right_slant point O of outer_circle origin shifted 0 ypart lrcorner outer_circle euro_circle buildcycle outer_circle right_line reverse inner_circle reverse right_slant hor_bar euro_radius 0 euro_radius 0 top_slant right_slant shifted euro_radiust teuro_r_offset euro_l_offset 0 bot_slant top_slant shifted 0 euro_l_shift A few applications Page 549 The euro symbol if trace_euro for i right_line right_slant top_slant bot_slant draw i withpen pencircle scaled ipt withcolor 5white endfor fi euro_topbar buildcycle top_slant hor_bar shifted 0 euro_v_delta right_slant hor_bar shifted 0 euro_v_deltateuro_width 2 euro_botbar buildcycle bot_s
70. form The displacement is defined as p shifted 4cm 2cm Ina similar fashion you can rotate a path You can even combine shifts and rotations First we rotate the path 15 degrees counter clockwise around the origin p rotated 15 foc YA This rotation becomes more visible when we also shift the path to the right by saying rotated 15 shifted 4cm 0cm Now we get Welcome to MetaPost Page 19 Transformations Note that rotated 15 is equivalent to p rotatedaround origin 15 It may make more sense to rotate the shape around its center This can easily be achieved with the rotatedaround command Again we move the path to the right afterwards p rotatedaround center p 15 shifted 4cm 0cm Welcome to MetaPost Page 20 Transformations Yet another transformation is slanting Just like characters can be upright or slanted a graphic can be p slanted 1 5 shifted 4cm 0cm The slant operation s main application is in tilting fonts The x coodinates are increased by a percentage of their y coordinate so here every x becomes x 1 5y The y coordinate is left untouched The following table summarizes the most important primitive transformations that MeTaPosT supports METAPOST code mathematical equivalent x y shifted a b x ay b x y scaled s sx sy x y xscaled s sx y x y yscaled s x sy x y zscaled u v xu yu xv yu x y slanted s x sy y x y rotated r x cos r
71. former expecting the name of a font in the form of a string the latter expecting a numeric to be used in the scaling of the font Should you choose not to set these yourself they default to cmr10 and 1 0 respectively However you can change the defaults as follows defaultfont defaultscale tir 12 These settings select Adobe Times at about 12pt You can also set these variables to CONTEXT related values For CONTEXT graphics they are set to defaultfont defaultscale truefontname Regular the bodyfontsize 10 content index reference Page 397 TpX text This means that they will adapt themselves to the current body font in this document file texgyrepagella reg ular and the current size of the bodyfont here 10 0pt 10 TRX text In the next example we will use a special mechanism for building graphics step by step The advantage of this method is that we can do intermediate calculations in Tpx Our objective is to write a macro that draws text along a circular path While doing so we want to achieve the following e the text should be properly kerned i e the spacing between characters should be optimal e the position on the circle should vary and e the radius of the circle should vary This implementation is not the most straightforward one but by doing it step by step at least we see what is involved Later we will see a better method If you run these examples yourself you mu
72. funny etex point 5 of p cp freedotlabel btex strut macros etex point 6 of p cp freedotlabel btex strut Can t we etex point 7 of p cp A few applications Page 487 Marking angles Unfortunately we can run into problems due to rounding errors Therefore we use a less readable but more safe expression for calculating the intersection points Instead of using point loc as endpoint we use loc shifted over a very small distance into the direction loc from ori In the assignment to 1 we replace loc by 1 eps arclength ori loc unitvector loc ori Marking angles A convenient METAPOST macro is unitvector When we draw a line segment from the origin to the point returned by this macro the segment has a length of 1 base point This macro has a wide range of applications but some basic knowlegde of vector algebra is handy The following lines of meTAPOsT code demonstrate the basics behind unitvectors pair uv pickup pencircle scaled 1mm autoarrows true draw fullcircle scaled 2cm withcolor 625red for i 10 35 40 20 85 15 draw origin i dashed evenly withcolor 625white drawarrow origin unitvector i scaled 1cm withcolor 625yellow endfor draw origin withcolor 625red The circle has a radius of 1cm and the three line segments are drawn from the origin in the direction of the points that are passed as arguments Because the vector has length of 1 we scale it to the radius to let it touch the
73. green fill y withcolor white blue fill w withcolor white for i r g b c m y draw i withcolor 5white endfor currentpicture currentpicture xsized size popcurrentpicture enddef A few applications Page 508 Color circles Here we first fill the primary circles next we fill the secondary ones These also cover the center which is why finally we fill the center with white The circle uses the following colors colorcircle 4cm 2 5 8 8 2 5 5 8 2 The next graphic demonstrates how the subpaths look that build the shapes A few applications Page 509 Color circles We did not mention what the push and pop commands are responsible for Scaling the current picture is well defined as long as we deal with one graphic However if the current picture already has some content this content is also scaled The push and pop commands let us add content to the current picture as well as manipulating the picture as a whole without any side effects The final result is put on top of the already drawn content Instead of the sequence pushcurrentpicture A few applications Page 510 Fool yourself currentpicture currentpicture transformations popcurrentpicture you can say pushcurrentpicture popcurrentpicture transformations Both are equivalent to draw image transformations For larger sequences of commands the push pop alternative gives a bit
74. his forthcoming books from the typesetting and layout down to the ves of the letters Seldom has an author had anything remotely like this power to control appearance of his or her work Knuth s TEX typesetting system has become well known wailable in many countries around the world By contrast his METAFONT system for desi of typefaces has not become as well known or available his article The Concept of a Meta Font Knuth sets forth for the first time the under hhilosophy of METAFONT as well as some of its products Not only is the concept exiting well executed butin my opinion the article is charmingly written as well However despit overall enthusiasm for Knuth s idea and article there are some points in it that I feel might A readers and since they are points that touch close to my deepest int artificial intelligence and esthetic theory I felt compelled to make some comments to important issues raised by The Concept of a Meta Font odd Figure 6 3 A background with split areas How do we define a background as in figure 6 2 Because Field provides us the positioned areas we can use Page backgrounds Edward R Tufte We thrive in informationthick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan l
75. i g d n 1 fais enddef vardef drawmidpoints expr p n save a b c d pair a b c d for x 0 upto length p 1 a point x of p b postcontrol x ofp d point x 1 of p c precontrol x 1 of p dodrawmidpoints a b c d n endfor enddef We apply this macro to a simple shape drawmidpoints fullcircle xscaled 300pt yscaled 50pt 1 A few more details Page 144 Curve construction When drawn this results in the points that makes up the curve We now add an extra iteration resulting in the yellow points drawmidpoints fullcircle xscaled 300pt yscaled 50pt 2 and get We don t even need that much iterations to get a good result The depth needed to get a good result depends on the size of the pen and the resolution of the device on which the curve is visualized for i 1 upto 7 drawmidpoints fullcircle xscaled 300pt i 10pt yscaled 50pt i 10pt i endfor A few more details Here we show 7 iterations in one graphic In practice it is not that trivial to determine the depth needed The next example demonstrates how the reso lution of the result depends on the length and nature of the segment drawmidpoints fullsquare xscaled 300pt yscaled 50pt randomized 20pt 10pt 5 A few more details exit lt dd gt gt Page 146 Inflection tension and curl Inflection tension and curl The meTAPOsT manual describes the meaning of as choose an inflec
76. in both directions and shifts over the zero vector Transform variables can save quite some typing and may help you to force consistency when many similar transformations are to be done Instead of changing the scaling shifting and other transformations you can then stick to just changing the one transform variable Constructing paths In most cases a path will have more points than the few shown here Take for instance a so called super ellipse Welcome to MetaPost Page 24 Constructing paths Ba 6 These graphics provide a lot of information In this picture the crosshair in the center is the origin and the dashed rectangle is the bounding box of the super ellipse The bounding box specifies the position of the graphic in relation to the origin as well as its width and height In the graphic on the right you can see the points that make up the closed path as well as the control points Each point has a number with the first point numbered zero Because the path is closed the first and last point coincide We ve used the commands and as path connecting directives In the next series of examples we will demonstrate a few more However before doing that we define a few points using the predefined z variables zo 0 5cm 1 5cm z1 2 5cm 2 5cm z2 6 5cm 0 5cm z3 3 0cm 1 5cm Welcome to MetaPost Here z1 is a short way of saying x1 y1 When a z variable is called the corresponding x and y variables ar
77. is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my over all enthusiasm for Knuth s idea and article there are some test 3 Page 441 Libraries ap pearance of his or her work Knuth s gx typeset ting system has become well known and available in many countries around the world By contrast his MeTAFONT system for designing families of typefaces has not become as well known or available In his ar ticle points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt com pelled to make some com ments to clarify certain important issues raised by The Concept of a Meta Font test 4 Figure 10 4 A continuous text typeset in a non standard shape spread over four areas tracing on Typesetting in METAPOST We can combine all those tricks although the input is somewhat fuzzy First we define a quote typeset in a circular paragraph shape startuseMPgraphic center build_parshape fullcircle scaled 8cm 0 0 0 baselinedistance strutheight strutdepth strutheight stopuseMPgraphic startshapetext center input douglas stopshapetext defineoverlay center useMPgraphic center We will surround this text with a circular line that we define as follows By using a buffer we keep thin
78. less sensitive for misinterpretation vardef ColorCircle expr method factor ca cb cc save u p path p p fullcircle shifted 1 4 0 image fill p rotated 90 withcolor transparent method factor ca fill p rotated 210 withcolor transparent method factor cb fill p rotated 330 withcolor transparent method factor cc enddef draw ColorCircle normal 5 red green blue xsized 3cm currentpicture currentpicture shifted 4cm 0 draw ColorCircle exclusion 5 red green blue xsized 3cm currentpicture currentpicture shifted 4cm 0 draw ColorCircle exclusion 1 red green blue xsized 3cm Special effects Page 335 Transparency color xcyan xcyan cmyk 1 0 0 0 color xmagenta xmagenta cmyk 0 1 0 0 color xyellow xyellow cmyk 0 0 1 0 draw ColorCircle exclusion 5 xcyan xmagenta xyellow xsized 3cm You can be tempted to use transparency as a convenient way to achieve soft colors In that case you should be aware of the fact that rendering transparent colors takes more time than normal colors When your printer does not support this feature natively the intermediate POSTSCRIPT file send to the printing engine is also larger content index reference Page 336 Transparency Fortunatey METAPOST provides a similar mechanism The last circle in the following row demonstrates how we can trigger colors proportionally to other colors Normally
79. need to generate a return value and as a result may not end with a semicolon You may consider the whole vardef to be encapsulated into parenthesis and thereby to be a self contained variable Adding additional parenthesis often does more harm than good vardef test expr a do tricky things with a manipulated_a enddef Here the tricky things become part of the return value which quite certainly is something that you don t want The three operator look alike macro definitions are less flexible and have the definition scheme enddef enddef bentianydeL xq best y enddefi primarydef x test y secondarydef x test y When defining macros using this threesome you need to be aware of the associated priorities When using these definitions you also have to provide your own grouping In the plain metaPosT macro collection plain mp you can find many examples of clever definitions The fol lowing simplified version of min demonstrates how we use the argument handler to isolate the first argument from the provided list simply by using two arguments content index reference Page 64 Pens vardef min expr u text t save min_u min_u u for uu t if uu lt u min_u uu fi endfor min_u enddef The special sequence is used to pick up a so called delimited argument vardef TryMe expr x we can now use which is just text enddef This feature is used in the definition of z as u
80. new pen using the pen command Then we define a path and make a pen out of it using the makepen macro The path should be a relatively simple one otherwise M eTAPOST will complain You can use makepen with the previously introduced withpen draw p withpen makepen 0 0 3cm 3cm and pickup pickup makepen 0 0 3cm 3cm draw p Welcome to MetaPost Page 69 Joining lines You can use makepen and makepath to convert paths into pens and vice versa Pens are very important when defining fonts and MeTAFONT is meant to be a font creation tool Since METAPOST has a slightly different audience it lacks some features in this area but offers a few others instead Neverthe less one can try to design a font using meTaPosT Of course pens are among the designers best kept secrets But even then not every O is a nice looking one Joining lines The way lines are joined or end is closely related to the way POSTSCRIPT handles this By setting the variables linejoin and linecap you can influence the drawing process Figure 1 1 demonstrates the alternatives The gray curves are drawn with both variables set to rounded By setting the variable miterlimit you can influence the mitering of joints The next example demonstrates that the value of this variable acts as a trigger Welcome to MetaPost AAA linejoin mitered linejoin mitered linejoin mitered linecap butt linecap rounded linecap squared linejoin rounded line
81. of the text MetaPost is Fun Typesetting in METAPOST Page 400 TEX text Before we typeset the text now available in pieces in pic ina circle we will first demonstrate what they look like You may like to take a look at the file mpgraph mp to see what is passed to METAPOST startMPdrawing pair len len origin for i 1 upto n draw pic i shifted len draw boundingbox pic i shifted len withpen pencircle scaled 25pt withcolor red len len xpart urcorner pic i xpart llcorner pic i 0 endfor stopMPdrawing We can call up this drawing with getMPdrawing but first we inform the compiler that our MeTarost drawing is completed MPdrawingdonetrue getMPdrawing This results in MetaPostisFun Compare this text with the text as typeset by TEx MetaPost is Fun Typesetting in METAPOST Page 401 TX text and you will see that the text produced by metarost is not properly kerned When putting characters after each other TeX uses the information available in the font to optimize the spacing between characters while METAPOST looks at characters as separate entities But since we have stored the optimal spacing in len we can let metarost do a better job Let s first calculate the correction needed startMPdrawing for i 1 upto n wid i abs xpart urcorner pic i xpart llcorner pic i posli len i wid il endfor stopMPdrawing Thi
82. p fullcircle scaled r randomized r rx r ry A few more details Page 147 Inflection tension and curl shifted i j scaled r pickup pencircle scaled a draw for k 0 upto length p point k of p endfor cycle withcolor draw for k 0 upto length p point k of p endfor cycle withcolor pickup pencircle scaled b draw for k 0 upto length p point k of p endfor cycle withcolor 625yellow draw for k 0 upto length p point k of p endfor cycle withcolor 625white for k 0 upto length p draw point k of p withcolor 625red endfor endfor endfor setbounds currentpicture to q enddef stopuseMPgraphic As you see not so much code is needed The graphics themselves were produced with a couple of commands like placefigure Circles with minimized inflection and 25 randomized points startMPcode A few more details e e Figure 2 3 Circles with minimized inflection and 25 randomized points content index reference Page 150 Inflection tension and curl amp Figure 2 5 Circles with minimized inflectiomandsS0 randomized points A few more details Page 152 Inflection tension and curl includeMPgraphic sample sample 4 4 stopMPcode The tension specifier can be used to influence the curvature To quote the MeTarost manual once more The tension parameter can be less than one but it must be at least 3 4 The following paths are the same Zl a Z2 zi
83. pair n n is returned We can draw a slightly better looking spring by drawing twice with a different pen The following commands use the spring macro implemented by the vardef path p p 0 0 spring 5cm 0 2 5cm 0 5cm 0 10 3cm 0 draw p withpen pencircle scaled 2pt draw p withpen pencircle scaled 1pt withcolor 8white This time we get WWV Since the spring macro returns a path you can do whatever is possible with a path like drawing an arrow WWW gt Or even watch how we use the neutral unit u to specify the dimensions This was keyed in as A few applications Page 476 Free labels drawarrow 0 0 spring 5cm 0 2 5cm 0 5cm 0 10 3cm 0 withpen pencircle scaled 2pt withcolor 625red and numeric u u Imm pickup pencircle scaled u 2 drawoptions withcolor 625red draw 0 0 spring 5u 0 25u 0 5u 0 10 30u 0 drawoptions dashed evenly withcolor 5white draw 0 0 spring 5u 0 35u 0 25 35 5u 0 10 40u 0 Free labels The metarost label macro enables you to position text at certain points This macro is kind of special because it also enables you to influence the positioning For that purpose it uses a special kind of syntax which we will not discuss here in detail pickup pencircle scaled imm path p p fullcircle scaled 3cm draw p withcolor 625yellow dotlabel rt right point 0 dotlabel urt upper right point
84. phenomena We can misuse transparant colors to illustrate how the effect becomes less with growing tension def sample expr p c draw p withpen pencircle scaled 2 0mm withcolor c enddef u icm zi 0 0 22 2u 4u z3 4u 0 for i 0 step 05 until 1 content index reference sample zi tension 75 i z2 z3 transparent 1 1 i 625red endfor A third magic directive is curl The curl is attached to a point between like curl 2 Anything between curly braces is a direction specifier so instead of a curl you may specify a vector like 2 3 a pair of numbers as in 2 3 or a direction like dir 30 Because vectors and angles are straightforward we will focus a bit on curl ZOM ae Zl Z2 p20 ernal iss 5 Mil oo Sermi aj 2 So a curl of 1 is the default When set to 1 the begin and or end points are approached Given the following definitions content index reference Page 160 Inflection tension and curl u cm z1 0 0 z2 2u 4u z3 4u 0 def sample expr p c draw p withpen pencircle scaled 2 5mm withcolor white draw p withpen pencircle scaled 2 0mm withcolor c enddef We can draw three curved paths sample zi curl 0 z2 curl 0 z3 625red sample z1 curl 2 z2 curl 2 z3 625yellow sample zi curl 1 z2 curl 1 z3 625white The third gray curve is the default situation so we could have left the curl
85. q shifted 0 i 111 found_point line l true rrr found_point line r false aae indent n abs xpart 111 xpart llcorner q width n abs xpart rrr xpart 111 Typesetting in METAPOST Page 433 Talking to Tex endfor stopuseMPgraphic startuseMPgraphic text save write parshape amp decimal n to mfun mp data txt for i 1 upto n write decimal indent i amp bp amp decimal width i amp bp to mfun mp data txt endfor write EOF to mfun mp data txt stopuseMPgraphic We can call this macro using the part we used in the previous examples startuseMPgraphic text includeMPgraphic text macro path p p 0 1 1 0 1 0 cycle scaled 65pt provide_parshape p shape path 5 baselinedistance offset baselinedistance distance between lines strutheight height of a line strutdepth depth of a line Typesetting in METAPOST strutheight height of first line stopuseMPgraphic After we called useMPgraphic text the resulting file looks as follows You can call up this file by its anony mous name MPdatafile since this macro gets the value of the graphic at hand parshape 8 21 25648bp 46 39665bp 16 79666bp 54 3987bp 6 52979bp 77 31822bp 1 44792bp 95 05238bp 1 77025bp 107 38231bp 6 4069bp 106 13466bp 14 96152bp 89 02438bp 31 50317bp 55 9419bp So reading in this file at the start of a paragraph will setup Tpx to follow this
86. rrr found_point line r false stopuseMPgraphic We can manipulate the heigth and depth of the lines to give different and maybe better results startuseMPgraphic text vars baselineskip 8pt strutheight 4pt strutdepth 2pt offset 4pt topskip s Bow 3 stopuseMPgraphic Typesetting in METAPOST This kind of graphic trickery in itself is not enough to get TX into typesetting within the bounds of a closed curve Since METAPOST can write information to a file and TeX can read sucha file a natural way to handle this is to let MeTAPOST write a parshape specification startuseMPgraphic text macro def provide_parshape expr p offset baselineskip strutheight strutdepth topskip includeMPgraphic text move includeMPgraphic text split includeMPgraphic text cutoff includeMPgraphic text draw includeMPgraphic text calc includeMPgraphic text loop includeMPgraphic text save Typesetting in METAPOST Page 432 Talking to Tx enddef stopuseMPgraphic We have to adapt the for loop to register the information about the lines After the loop we write those values to a file using another loop startuseMPgraphic text loop path line pair 111 rrr numeric vvsize n n 0 if strutheight strutdepth lt baselineskip vvsize vsize elise vvsize vsize div baselineskip baselineskip fi for i topskip step baselineskip until vvsize line ulcorner q urcorner
87. run time The first method is the most independent one which has its advantages if we want to use the graphics in other applications too The second method works well in graphics where parts of the definitions change between invocations of the graphic This method follows the template startuseMPgraphic whatever stopuseMPgraphic startuseMPgraphic result includeMPgraphic whatever stopuseMPgraphic useMPgraphic result The disadvantage of this method is that it cannot be combined with btex etex since it is nearly impossible to determine when how and to what extent the content of a graphic should be expanded before writing it to the temporary METAPOST file A few applications Page 519 Growing graphics Therefore we will demonstrate how buffers can be used This third method closely parallels the first way of defining graphics A nice side effect is that we can easily typeset these buffers verbatim which we did to typeset this document We are going to do a classic compass and straightedge construction the bisection of a line segment joining two arbitrary points We will construct five graphics where each one displays one step of the construction We will embed each graphic in a start stop command Later we will see the advantage of this strategy startbuffer a def start_everything enddef def stop_everything enddef stopbuffer We are going to draw a few dots and to force consistency we first define
88. shape The final implementation is a bit more complicated since it takes care of paths that are not centered around the origin and don t start at the top point We achieve this by moving the path to the center cp center p q p shifted cp The arbitrary starting point is taken care of by a slightly more complicated path cutter First we make sure that the path runs counterclockwise if xpart directionpoint t of q lt 0 q reverse q fi Typesetting in METAPOST exit lt a d gt amp 10 6 Page 435 Libraries Knowing this we can split the path in two using a slightly different splitter cutbefore t if xpart point 0 of q lt 0 amp q fi cutafter b cutbefore b if xpart point 0 of q gt O amp q fi cutafter t H tal f i H OF a As always when implementing a feature like this some effort goes into a proper user interface In doing so we need some 1X trickery that goes beyond this text like collecting text and splitting of the part needed Also we want to be able to handle multiple shapes at once like the next example demonstrates Libraries The macro discussed in the previous section is included in one of the mMetarost libraries so we first have to say useMPlibrary txt We define four shapes They are not really beautiful but they demonstrate what happens in border cases For instance too small first lines are ignored First we define a circle Watch how the dimensions are s
89. specifier out of the expression A few more details Page 161 Inflection tension and curl The curly specs have a lower bound of zero and no upper bound When we use meTarost maximum value of infinity instead of 2 we get These curves were defined as sample z1 curl OP ce Z 25 Cea 0 z3 625red sample z1 curl infinity z2 curl infinity z3 625yellow sample z1 curl Wp eo PQ oo AEL 1 z3 625white It may sound strange but internally MeTarost can handle larger values than infinity sample z1 curl infinity z2 curl infinity z3 625red sample z1 curl 4infinity z2 curl 4infinity z3 625yellow sample z1 curl 8infinity z2 curl 8infinity z3 625white content index reference Page 162 Inflection tension and curl Although this is quite certainly undefined behaviour interesting effects can be achieved When you turn off METAPOST S first stage overflow catcher by setting warningcheck to zero you can go upto 8 times infinity which being some 2 is still far from what today s infinity is supposed to be As the built in mMetaPost command accepts the curl and tension directives as described in this section you will now probably understand the following plain Metarost definitions def curl 1 curl 1 enddef Clear SSS tension infinity enddef def a tension atleast 1 enddef A few more details Page 163 Transformations These
90. technical drawing pur poses We will see that MeTarost can fill in some gaps in TFX especially its lack of graphic capabilities We will demonstrate that graphics can make a document more attractive even if it is processed in a batch processing system like TEx Most of all we will see that embedding metarost definitions in the TeX source enables a smooth communication between both programs Introduction The best starting point for using meTAPosT is the manual written by its author John Hobby You can find this manual at every main TeX repository Also a copy of the METAFONT book from Donald Knuth is worth every penny if only because it will give you the feeling that many years of graphical fun lays ahead In this METAFUN manual we will demonstrate how you can embed graphics in a TeX document but we will also introduce most of the features of MeTAPOST For this reason you will see a lot of MeTarost code For sure there are better methods to solve problems but I have tried to demonstrate different methods and techniques as much as possible I started using metarost long after I started using Tgx and I never regret it Although I like Tex very much I must admit that sometimes using meTarosT is even more fun Therefore before we start exploring both in depth I want to thank their creators Donald Knuth and John Hobby for providing me these fabulous tools Of course I also need to thank Han Th Thanh for giving the Tpx community PDFTgx a
91. tickstep 2 ticklength ticklength 2 drawticks fullsquare xscaled 4cm yscaled 3cm The ticklength variable specifies the length of a tick Here we manipulated both the variables to get a more advanced system If visualizing a path would mean that we would have to key in al those draw commands you could hardly call it a comfortable tool Therefore we can say drawwholepath fullsquare scaled 3cm rotated 30 randomized 5mm The drawwholepath command shows everything except the axis Debugging Page 452 Libraries If even this is too much labour you may say visualizepaths This redefines the draw and fill command in such a way that they also show all the information visualizepaths draw fullsquare scaled 3cm rotated 30 randomized 2mm You may compare this feature to the showmakeup command available in CONTEXT that redefines the Tex prim itives that deal with boxes glues penalties and alike Debugging Page 453 Libraries Of course you may want to take a look at the MetaPost manual for its built in more verbose tracing options One command that may prove to be useful is show that you can apply to any variable This command reports the current value if known to the terminal and log file Debugging Page 454 Libraries The previous picture shows what is typeset when we also say showmakeup This command visualizes T X s boxes skips kerns and penalties As you can see there are so
92. token generic suffix generic suffix empty generic suffix tag generic suffix J macro de nition macro heading replacement text enddef macro heading def Symbolic token delimited part undelimited part vardef generic variable delimited part undelimited part vardef generic variable delimited part undelimited part binary def parameter symbolic token parameter delimited part empty delimited part parameter type parameter tokens METAPOST syntax Page 572 Syntax diagrams parameter type expr suffix text parameter tokens parameter parameter tokens parameter parameter Symbolic token undelimited part gt empty parameter type parameter precedence level parameter expr parameter of parameter precedence level primary secondary tertiary METAPOST syntax Page 573 Syntax diagrams binary def primarydef secondarydef tertiarydef pseudo procedure drawoptions option list label label suffix expression pair expression dotlabel label suffix expression pair expression labels label suffix point number list dotlabels label suffix point number list textext label suffix expression freelabel expression pair expression pair expression freedotlabel expression pair exp
93. upto length p inside i of p endfor withcolor 625red Whenever you define a pen METAPOST stores its characteristics in some private variables which are used in the top and alike directives The penoffset is a built in primitive and is defined as the point on the pen furthest to the right of the given direction Deep down in metarost pens are actually simple paths and therefore METAPOST has a notion of a point on the penpath In the MeTAFONT book and metarosT manual you can find in depth discussions on pens We re still not there Like in a previous example we need to shift over twice the pen width To get good results we should determine the width of the pen at that particular point which is not trivial The more general solution which permits us to specify the amount of shifting is as follows vardef penpoint expr pnt of p save n d numeric n d A few more details n d if pair pnt pnt else pnt 1 fi point n of p shifted penoffset direction n of p of currentpen scaled d enddef When the point specification is extended with a distance in which case we have a pair expression the point and distance are derived from this specification First we demonstrate the simple case draw penpoint 0 of p for i 1 upto length p 1 penpoint i of p endfor cycle withcolor 625red In the next graphic we draw both an inner and and outer path draw penpoint 0 2 of p for i 1 upto length p 1
94. using this macro When we want to improve the readability we have to use intermediate variables Since the macro is expected to return a path we must make sure that the content matches this expectation vardef spring expr a b w h n pair vec path pat numeric len numeric ang vec b a A few applications Page 474 Simple drawings pat for i 1 upto n 1 if odd i fi w 2 i endfor 0 n pat 0 0 0 h pat shifted 0 h 0 n h 0 n 2h len xpart vec ypart vec nt2h ang 90tangle vec pat yscaled len rotatedaround origin ang shifted a enddef If you use vardef then the last statement is the return value Here when p spring z1 z2 75cm 2 10 is being parsed the macro is expanded the variables are kept invisible for the assignment and the path at the end is considered to be the return value In a def the whole body of the macro is pasted in the text while in a vardef only the last line is visible We will demonstrate this with a simple example def one n n n nti enddef def two n n 1 m n enddef Now when we say parria numeri cini 6 w 10 8 amp B CMe 8 ID B WHO F we definitely get an error message This is because when macro two is expanded METAPOST sees something By changing the second definition in vardef two dg n n enddef A few applications the increment is expanded out of sight for b and the
95. you must make sure that the encoding of the font that you use matches your expectations However as we overload this macro it does not really matter since the string is passed to TeX anyway For instance UTF encoded text should work fine as CONTEXT itself understands this encoding Linear equations In the previous sections we used the assignment operator to assign a value to a variable Although for most of the graphics that we will present in later chapters an assignment is appropriate specifying a graphic in terms of expressions is not only more flexible but also more in the spirit of the designers of METAFONT and METAPOST The MeTAFONT book and metarost manual provide lots of examples some of which involve math that we don t consider to belong to everyones repertoire But even for non mathematicians using expressions can be a rewarding challenge Welcome to MetaPost Page 77 Linear equations The next introduction to linear equations is based on my first experiences with MeTarost and involves a math ematical challenge posed by a friend I quickly ascertained that a graphical proof was far more easy than some proof with a lot of sin this and cos that and long forgotten formulas I was expected to prove that the lines connecting the centers of four squares drawn upon the four sides of a quadrilateral were perpendicular see figure 1 2 This graphic was generated with the following command placefigure here fig pr
96. you want points to touch instead of being overlayed We can achieve this by defining point q to be located on top of the midpoint pair q q top 5 llcorner p lrcorner p The predefined macro top moves the point over the distance similar to the current pen width A few more details Page 171 Only this far Because we are dealing with two drawing operations and since the path inside is drawn through the center of points we need to repeat this move in order to draw the red path really inside the other one pair q q top top 5 llcorner p lrcorner p Operations like top and its relatives bot 1ft and rt can be applied sequentally LYS N We already showed that q was defined as a series of rotations draw q q rotated 90 q rotated 180 rotated 270 cycle withcolor 625red q yi As an intermezzo we will show an alternative definition of q Because each point is rotated 90 degrees more we can define a macro that expands into the point and rotates afterwards Because each consecutive point on A few more details Page 172 Only this far the path is rotated an additional 90 degrees we use the METAPOST macro hide to isolate the assignment The hide command executes the hidden command and afterwards continues as if it were never there You must not confuse this with grouping since the hidden commands are visible to its surroundings def qq q hide q q rotated 90 enddef draw qq qq qq q
97. 1 dotlabel top top point 2 dotlabel ulft upper left point 3 A few applications Page 477 Free labels dotlabel 1ft left point 4 of p dotlabel 11ft lower left point 5 of p dotlabel bot bottom point 6 of p dotlabel 1rt lower right point 7 of p The label command just typesets a text while dotlabel also draws a dot at the position of the label The thelabel command returns a picture top upper left upper right right lower left lower right bottom There is a numeric constant labeloffset that can be set to influence the distance between the point given and the content of the label When we set the offset to zero we get the following output A few applications This kind of positioning works well as long as we know where we want the label to be placed However when we place labels automatically for instance in a macro we have to apply a few clever tricks There are fore sure many ways to accomplish this goal but here we will follow the mathless method The previous graphic visualizes the bounding box of the labels This bounding box is rather tight and therefore the placement of labels will always be suboptimal Compare the alignment of the left and rightmost labels The btex etex method is better since then we can add struts like btex strut right etex A few applications Page 479 Free labels to force labels with uniform depths and heights The next graphic demonstrat
98. 25cm 0 50cm 1cm SP test_shade origin shifted 25cm 0 origin Ocm 1cm test_shade origin shifted 25cm 0 origin 25cm 1cm test_shade origin shifted 25cm 0 origin 50cm 1cm DG In a similar fashion we can define a linear shade This time we only pass two points and two colors Special effects Page 333 Shading def test_shade expr a b pickup pencircle scaled 1mm color ca ca MPcolorfa color cb cb MPcolor b color cc cc MPcolorf c sh define_linear_shade a b ca cb fill fullsquare scaled 2cm withshade sh draw a withcolor cc draw b withcolor cc enddef Although one can control shading to a large extend in practice only a few cases really make sense test_shade origin origin shifted 1cm 0 test_shade origin shifted 1icm 0 origin shifted 1cm 0 test_shade origin shifted 1cm 1cm origin shifted 1cm icm h Special effects Page 334 Transparency Transparency In the screen version we use a light gray background color As a result some of the transparency methods demonstrated here give unexpected results The A4 version of this document demonstrates the real effects Although transparent colors have been around for some time already it was only around 2000 that they made it as a high level feature into document format languages like PDF Supporting such a feature at a higher abstraction level is not only more portable but also
99. 5yellow refill currentpicture withshade sh redraw currentpicture withpen pencircle scaled 2pt withcolor 5white Before we show a next trick we draw a few circles Special effects fill fullcircle scaled 2cm withcolor yellow fill fullcircle scaled 2cm shifted 3cm 0 withcolor red The yellow and red color do not match the main document colors but this is no problem we can remap them without spoiling the original definition fill fullcircle scaled 2cm withcolor yellow fill fullcircle scaled 2cm shifted 3cm 0 withcolor red remapcolor yellow 625yellow remapcolor red 625red recolor currentpicture resetcolormap Special effects Page 358 Changing colors We can combine the inclusion technique with remapping colors This time using an artist impression of one of Hasselts Canals gracht in Dutch loadfigure gracht mp number 1 scaled 5 If you think that the sky is too bright in this picture and given that you also know which color is used you can fool the reader by remapping a few colors loadfigure gracht mp number 1 scaled 5 color skycolor skycolor 0 8 0 90 1 0 color watercolor watercolor 0 9 0 95 1 0 remapcolor skycolor 8skycolor remapcolor watercolor 8watercolor recolor currentpicture resetcolormap Special effects Including another metarost graphic refilling redrawing and recoloring are all relatively simple features tha
100. AFUN we make sure that we also reset some otherwise global variables like color pen and some line properties Welcome to MetaPost Page 117 Making graphics A few more details In this chapter we will see how to define a metaPpost graphic and how to include it in a document Since the exact dimensions of graphics play an important role in the placement of a graphic we will explore the way a bounding box is constructed We will also pay attention to the usage of units and the side effects of scaling and shifting since they can contradict our expectations in unexpected ways Furthermore we will explore a few obscure areas Making graphics In this manual we will use metarost in a rather straightforward way and we will try to avoid complicated math as much as possible We will do a bit of drawing clipping and moving around Occasionally we will see some more complicated manipulations When defined as stand alone graphic a Metarost file looks like this Let s draw a circle beginfig 7 draw fullcircle scaled 3cm withpen pencircle scaled icm endfig end A few more details Page 118 Making graphics The main structuring components in such a file are the beginfig and endfig macros Like in a big story the file has many sub sentences where each sub sentence ends with a semi colon Although the end command at the end of the file concludes the story putting a period there is a finishing touch Actually after the e
101. AHT LHT DHT LAL et LA LET LHT IT Let Dt JT ST LHT IHT LHT LHT UA PHT IT LHA LHT LHH IAT LHT LHI PHT IHT LENY HY LIHA AHT IHY AHT LHAT IHT JHT IHY LHT LHH LHT IHT LHT IAG IHY LHT LT LMT LT LA HHT HAT Lett LHT LE LAT JA LHT LT Lat IAT DHT HT DHT LHT LA IT LHT Mt LIHT LT LHA LING LHT LA LHA JHT IHT HHT LHH IHT LHH DHU LHT A 3AT LHT IHT DAT LHA Lht La LH AHT LHA LHT LHT JAT IHT IHY LHT LIH LET DHT AHT LHT LY IHT SHT JHA LHA DHIT LHT IHAT LHT IHY LHT LHH LHT LHT IHT LHH IHHT ST JHT LHT IHT Lht LHT IHT LHT LHT HHT LHT Leet LAY LHT LHT LHE IHAT AMT IHA IHA HAT LMU HT LHT LIHT IHT LHAT AHT LHT LT LHN AHT IHT IHT HAA LHAT Let LHT LMT JHI IHA IHT IHT LHI IHT Lht LMT IHT HT I reasons why MeTAPOST is fun To mention a few you can enhance the layout with graphic ornaments you can tune your graphics at runtime and simple high quality graphics can be very effective The previous graphics draws exactly 1001 lines in a scratch numbers in a wall fashion In 1998 the NTG did a survey among its members and in the report we used this fuzzy counter to enhance the rather dull tables system users Atari 10 4 MIHI MSDOS 49 1 IAT THT LAA AT LAT LAT LAT AT LT HT II OS 2 9 4 JH mM MacOS 5 7 WMiI UNIX 51 9 JHE IM IHT LHT IHT LAT IHT IHT IHI T aT WINDOWS 64 2 LH UM IH IHT IHI IHA IHT IHI IAT LHA IHT AHT LHT II Table 7 1 Operating system n 106 Table 7 1 demonstrates how scratch numbers can be used An interesting side effect is that when you look long e
102. According to METAPOST when we leave the Earth straight upwards and want a smooth trajectory we have to pass through outer space startMPcode inclt eMPgraphic gamble Gamble 120 aa 0 1 0 bb _ stopMPcode A few applications Page 556 Killing time Given that we want a smooth path as well as a short journey we can best follow Mars path Here we face the risk that when we travel slower than Mars does we have a problem startMPcode includeMPgraphic gamble Gamble 120 aa dir 90 precontrol O of b rotated 90 bb stopMPcode We can even travel a shorter path when we leave Earth at the surface that faces the point of arrival startMPcode includeMPgraphic gamble Gamble 120 aa precontrol 0 of b rotated 90 bb stopMPcode A few applications Page 557 Killing time In the end we decide that although the trajectories look impressive we will not trust our lives to METAPOST A beautiful path is not neccessarily a good path But even then this macro provides a nice way to experiment with directions controls and tensions A few applications METAFUN macros CONTEXT comes with a series of MetaPOST modules In this chapter we will summarize the most important Tex and METAPOST macros More information can be found in the documentation of the modules There are several ways to use the power of METAFUN either or not using CONTEXT 1 You can create an independent mp file and pr
103. At first sight in the next situation we would expect something similar because we simply copy the same circle 5 times However due to the way we have implemented shading in CONTEXT we do indeed copy the circles but the shade definition is frozen and the same one is used for all 5 circles This means that the center of the shading stays at the first circle circular_shade fullcircle scaled icm 0 MPcolor a MPcolor b picture s s currentpicture currentpicture nullpicture for i 0 step 2cm until 8cm addto currentpicture also s shifted i 0 endfor Unlike Tex meTAPOsST does not keep its specials attached to the current path and flushes them before the graphic data Since we use these specials to register shading information it is rather hard to tightly connect a specific shade with a certain fill especially if an already performed fill is not accessible which is the case when we copy a picture This may seem a disadvantage but fortunately it also has its positive side In the next example we don t copy but reuse an already defined shade By storing the reference to this shade and referring to it by using withshade we can use a shade that operates on multiple shapes Special effects sh define _circular_shade origin origin 0 8cm MPcolor a MPcolor b for i 0 step 2cm until 8cm fill fullcircle scaled 1cm shifted i 0 withshade sh endfor The low level macro def ine_circular_shade is fed wi
104. Before we present one way of dealing with this complexity we will elaborate on the nature of such graphics When TEX entered the world of typesetting desktop printers were not that common let alone color desktop printers But times have changed and nowadays we want color and graphics and if possible we want them integrated in the text To accomplish this several options are open Use a backend that acts on the typeset text This is the traditional way using specials to embed directives in the DVI output file Use the power of a second language and pass snippets of code to the backend which takes care of proper handling of those snippets of text Impressive results are booked by passing POSTSCRIPT to the DVI file Extend Tgx in such a way that Tpx itself takes care of these issues This is the way PDFTpxX and its decendants work content index reference The first method is rather limited although for business graphics the results are acceptable The second method is very powerful but hardly portable since it depends on the DVI to POSTSCRIPT postprocessor But what about the third method There has been some reluctance to divert from traditional Tpx and DVI but with the development of PDFTgx the third option has become a viable option Much of what I will discuss here can be realized in DVI using a dedicated postprocessor to extract the information needed Although we believe that the PDFTI X way is the natural way to go CONT
105. EXT MkII also supports the same mechanism in DVI In MKIV we use the built in mechanism As said a decent portion of TgX s attention_is focused on breaking paragraphs into lines and determining the optimal point to split off the page Tryihg to locate the optimal points te break lines is a dynamic process The space between words is flexible atid we don t know in advance when a d or piece of a word maybe it s best to talk of typographic instead will end up on the page It might even cross the page boundary In the previous paragraph iwordland globs are encircled and connected by an arrow This graphic can be drawn only when the position and dimensions are known Unfortunately this information is only available after the paragraph is typeset and the best breakpoints are chosen Because the text must be laid on top of the graphic the graphic must precede the first word in the typeset stream or it must be positioned on a separate layer In the latter case it can be calculated directly after the paragraph is typeset but in the former case a second pass is needed Because such graphics are not bound to one paragraph the multi pass option suits better because it gives us more control the more we know about he final state the better we can act upon it Think of graphics on the first page that depend on the content of the last page or as in this paragraph backgrounds that depend on the typeset text
106. IPT and converted into Metarost by the PSTOEDIT program The resulting graphic is imported analyzed and processed conforming the specifications of graphictext By default the shapes are filled after they are drawn This has the advantage that in characters built out of pieces disturbing lines fragments are covered The drawback is that you get only half the linewidth You can reverse the drawing order by adding the reversefill1 directive The previous graphic then comes out as content index reference Page 365 Outline fonts graphictext bf Fun scaled 4 zscaled 1 1 5 reversefill withdrawcolor blue withfillcolor 5white withpen pencircle scaled 5pt The reversefill directive can be countered by outlinefill The next example is taken from the MAKEMPY manual It demonstrates that you can combine Tpx s powerful line breaking with metAPost s graphic capabilities startuseMPgraphic quotation srap q picture one one image graphictext Special effects MPstring text scaled 1 5 withdrawcolor 625blue withfillcolor 625white withpen pencircle scaled ipt picture two two image graphictext MPstring author scaled 2 withdrawcolor 625red withfillcolor 625white withpen pencircle scaled 2pt currentpicture one addto currentpicture also two shifted lrcorner one shifted 1 125 lrcorner two shifted 0 1 250 ypart urcorner two setbounds current
107. Location so the previous definition is the same as StartPage fill Area Text Text shifted Location Text Text withcolor 85white StopPage The following definition fills and draws the margin and text areas startuseMPgraphic page StartPage pickup pencircle scaled 2pt fill Page withcolor 625white Page backgrounds Page 293 Crossing borders fill Field OuterMargin Text withcolor 850white fill Field Text Text withcolor 850white draw Field OuterMargin Text withcolor 625red draw Field Text Text withcolor 625red StopPage stopuseMPgraphic This background is assigned to the page layer by saying defineoverlay page useMPgraphic page setupbackgrounds page background page As you can see in figure 6 3 the text is typeset rather tightly between the left and right margins This can easily be solved by enlarging the areas a bit The next example demonstrates this on the text area which is shown in figure 6 4 startuseMPgraphic page StartPage pickup pencircle scaled 2pt fill Page withcolor 625white fill Field Text Text enlarged 5cm withcolor 850white draw Field Text Text enlarged 5cm withcolor 625red StopPage stopuseMPgraphic The enlarged macro can be used like shifted and accepts either a numeric or a pair Page backgrounds d Knuth has spent the past several years working on a system allowing him to control r pects of the design of his f
108. METAFUN context mkiv October 8 2010 Hans Hagen Introduction This document is about Metarost and Tx The former is a graphic programming language the latter a typo graphic programming language However in this document we will not focus on real programming but more on how we can interface between those two languages We will do so by using CONTgXT a macro package writ ten in TeX in which support for MeTarost is integrated in the core The TeX macros are integrated in CONTEXT and the MetarosT macros are bundled in METAFUN When Donald Knuth wrote his typographical programming language Tpx he was in need for fonts especially mathematical fonts So as a side track he started writing METAFONT a graphical language When you read between the lines in the MeTAaFONT book and the source code the name John Hobby is mentioned alongside complicated formulas It will be no surprise then that since he was tightly involved in the development of METAFONT after a few years his MeTAPosT showed up While its ancestor METAFONT was originally targeted at designing fonts METAPOST is more oriented to drawing graphics as used in scientific publications Since METAFONT produced bitmap output some of its operators make use of this fact MeTaPosT on the other hand produces POSTSCRIPT code which means that it has some features not present in METAFONT and vice versa With METAFUN I will demonstrate that MeTarost can also be used or misused for less
109. MYK color space is also supported The truefontname macro communicates the running font from Tgx to MeTaPosr Instead of such low level code one can of course also use the textext macro However as we do the typesetting in Tex in MKIV this is the way to go Special effects vardef SampleText expr t draw textext t scaled 5 enddef SampleText SampleText SampleText SampleText SampleText SampleText colored a 1 t colored a 1 t colored a 1 t colored a 1 t colored a 1 t colored a 1 t As expected we get Page 338 Transparency 5 r 1 Much Of This 5 g 1 Functionality 5 b 1 Was Written 5 c 1 While Listening 5 m 1 To the CD s Of 5 y 1 Tori Amos Currently the 12 in PDF available transparency methods are supported You can use both numbers and names As you may expect both CONTEXT and METAFUN support transparency in the same way Figure 8 1 shows how the method affects the result In the future we may also support more control over the individual methods Special effects Page 339 Transparency screen overlay softlight hardlight colordodge colorburn darken lighten difference exclusion Figure 8 1 The 12 transparancy alternatives by name Special effects In CONTEXT a transparent color is defined in a similar way as normal colors The transparency method is specified with the a key either by number or by name and the factor t
110. OST clip is not the same as a video clip although we can use METAPOST to produce a video clip stopbuffer We can call up such a buffer as if it were an external figure Figure 8 6 shows the result This time we use a different clip path startMPclip text clip clip currentpicture to fullcircle shifted 5 5 xscaled width yscaled height stopMPclip To load a buffer we have to specify its name and type as in placefigure here fig clipped text 1 A clipped buffer text clip nx 1 ny 1 mp text clip externalfigure sample type buffer width 4cm The next few lines demonstrate that we can combine techniques like backgrounds and clipping startuseMPgraphic clip outline draw fullcircle xscaled overlaywidth yscaled overlayheight Special effects Special effects Page 347 Clipping METAPOST Clip is 1 the same as a video clip although we can use METAPOST to oduce a video cli Page 348 Clipping METAPOST clip is the same as a video clip although we can use METAPOST to oduce a video chi Figure 8 7 A clipped buffer text In most cases the clip path will be a rather simple path and defining such a path every time you need it can be annoying Figure 8 8 shows a collection of predefined clipping paths These are available after loading the METAPOST clipping library useMPlibrary clp We already saw how the circular clipping path was defined The diamond is defined in a simil
111. TEXT MKIV which brings down the runtime including runtime calls to inde pendent CONTEXT runs for the outline examples to some 45 seconds on a 2 2 Gig Dell M90 Given that at the time of writing this over 1700 graphics are generated on the fly this is not bad at all The document style is not that complicated The main complication in such a document is to make sure that METAPOST is operating under the same font regime As document font we use the URW Palatino for the running text combined with Computer Modern Typewriter Because this document is available as paper and screen document some large graphics are scaled down in the screen version content index reference We don t use any special tricks in typesetting this document but when we added the section about trans parency a dirty trick was needed in a few cases order to get the described results Because the screen docu ment has gray backgrounds exclusive transparencies come out wrong In the function drawing example we use the following trick to get a black background behind the graphics only We have a buffer that contains a few lines of code picture savedpicture savedpicture currentpicture currentpicture nullpicture draw savedpicture withcolor black draw savedpicture Since we use buffers for the graphics as well we can now process a buffer with name example as follows processbuffer example wipe This means that the example code is included
112. TaPosT available in LUAT X there is no need for external images and we can collect them in libraries as we will see later on Integrated graphics An integrated graphic is defined in the document source or in a style definition file The most primitive way of doing this is just inserting the code startMPcode fill fullcircle scaled 200pt withcolor 625white stopMPcode Such a graphic is used once at the spot where it is defined In this document we also generate graphics while we finish a page so there is a good chance that when we have constructed a graphic which will be called on the next page the wrong graphic is placed For this reason there are are more convenient ways of defining and using graphics which have the added advantage that you can predefine multiple graphics thereby separating the definitions from the usage Embedded graphics Page 204 Integrated graphics The first alternative is a usable graphic Such a graphic is calculated anew each time it is used An example of a usable graphic is startuseMPgraphic name fill fullcircle scaled 200pt withcolor 625yellow stopuseMPgraphic When you put this definition in the preamble of your document you can place this graphic anywhere in the file saying useMPgraphic name As said this graphic is calculated each time it is placed which can be time consuming Apart from the time aspect this also means that the graphic itself is incorporated many times The
113. The arguments to these macros are as follows hlingrid Min Max Step Length Width vlingrid Min Max Step Length Height hloggrid Min Max Step Length Width vloggrid Min Max Step Length Height content index reference Page 377 Grids The macros take the following text upto the semi colon into account and return a picture We will now apply this knowledge to a more meaningful example First we draw a grid You can use the grid drawing macros to produce your own paper for instance using the following mixed Tpx METAFUN code startMPpage StartPage width PaperWidth height PaperHeight unit cm drawoptions withpen pencircle scaled 2pt withcolor 8white draw vlingrid 0 width unit 1 10 width height draw hlingrid 0 height unit 1 10 height width drawoptions withpen pencircle scaled 5pt withcolor 4white draw vlingrid 0 width unit 1 width height draw hlingrid 0 height unit 1 height width StopPage stopMPpage This produces a page as in figure 9 1 with a metric grid If you re hooked to the inch you can set unit lin If you want to process this code you need to wrap it into the normal document producing commands setupoutput pdftex setupcolors state start starttext Functions Page 378 Grids Figure
114. Z N f N NAL NL NL ZN ZN You can often follow several routes to reach the same solution Consider for instance the following graphic fill 0 0 ww 0 ww hh w hh w h 0 h cycle fill ww 0 w 0 w hh cycle Welcome to MetaPost The points that are used to construct the paths are defined using the constants w h ww and hh These are defined as follows w 4cm h 2cm ww 1cm hh 1 5cm In this case we draw two shapes that leave part of the rectangle uncovered If you have a background this technique allows the background to show through the graphic A not uncommon practice when making complicated graphics is to use unfill operations Since METAPOST provides one let us see what happens if we apply this command fill 0 0 w 0 w h 0 h cycle unfill ww 0 w hh ww hh cycle content index reference Page 47 Drawing pictures This does not always give the desired effect because METAPOST s unfill is not really an unfill but a i11 with color background Since this color is white by default we get what we just showed So if we set background to black using background black we get Of course you can set the variable background to a different color but this does not hide the fact that MeTAaPOST lacks a real unfill operation Welcome to MetaPost Page 48 Drawing pictures Since we don t consider this unfill a suitable operator you may wonder h
115. Z23 x22 d y22 c z24 x21 d y21 c z31 x31 ye 3 z32 x32 yep z33 x32 f y32 e z34 x31 f y3 e z41 x41 y41 z42 x42 y42 Z43 x42 h y42 g z44 x41 h y41 g pickup pencircle scaled 5pt draw z11 z12 z13 z14 cycle draw z11 z13 draw z12 z14 draw z21 z22 z23 z24 cycle draw z21 z23 draw z22 z24 Welcome to MetaPost Page 80 Linear equations z31 z32 z33 z34 cycle draw z31 z33 draw z32 z34 zZ41 z42 z43 z44 cycle draw z41 z43 draw z42 z44 zi 0 5 z11 z13 z2 0 5 z221 223 z3 0 5 z31 z233 z4 0 5 z41 z43 draw zi z3 dashed evenly draw z2 z4 dashed evenly z0 whatever z1 z3 whatever z2 z4 mark_rt_angle z1 z0 z2 z2 is not used at all if show_labels gt O draw_problem_labels fi endgroup enddef stopMPdefinitions Because we want to call this macro more than once we first have to save the locally used values Instead of declaring local variables one can hide their use from the outside world In most cases variables behave globally If we don t save them subsequent calls will lead to errors due to conflicting equations We can omit the grouping commands because we wrap the graphic in a figure and figures are grouped already We will use the predefined z variable or actually a macro that returns a variable This variable has two com ponents an x and y coordinate So we don t save z
116. a few semi colons draw if n 10 p else q fi withcolor red Adding semi colons after p and q will definitely result in an error message since the semi colon ends the draw operation and withcolor red becomes an isolated piece of nonsense There is no case statement available but for most purposes the following extension is adequate draw p withcolor if n lt 10 red elseif n 10 green else blue fi There is a wide repertoire of boolean tests available if picture p if known al if odd als if cycle q Of course you can use and or not and to construct very advanced boolean expressions If you have a bit of programming experience you will appreciate the extensive support of conditionals in METAPOST content index reference Page 55 Loops Loops Yet another programming concept present in METAPOST is the loop statement the familiar for loop of all programming languages for i 0 step 2 until 20 draw 0 i endfor As explained convincingly in Niklaus Wirth s book on algorithms and datastructures the for loop is the natural companion to an array Given an array of length n you can construct a path out of the points that make up the array draw for i 0 step 1 until n 1 p i endfor pln If the step increment is not explicitly stated it has an assumed value of 1 We can shorten the previous loop construct as follows draw for i 0 upto n 1 pli endfor pln After seeing if in action
117. a line height inter paragraph white space setupwhitespace big Of course we use colors since on computer displays they come for free setupcolors state start definecolor red r 75 definecolor yellow r 75 g 75 definecolor gray s 50 definecolor white s 85 Defining styles Page 458 Adaptive buttons Because it is an interactive document we have to enable hyperlinks and alike However in this style we disable the viewer s highlight a hyperlink when it s clicked on feature We will use a menu so we enable menus Later we will see the contrast color hyperlinks gets that color when we are already on the location in action setupinteraction state start click off color red contrastcolor gray menu on The menu itself is set up as follows Because we will calculate menu buttons based on their position on the page we have to keep track of the positions Therefore we set the position variable to yes setupinteractionmenu right frame off position yes align middle topoffset 75cm bottomoffset 75cm color gray contrastcolor gray style bold before after Defining styles The menu content is rather sober just a list of topics and a close button Later we will define the command that generates topic entries The alternative right lets the topic list inherit its characteristics from the menu startinteractionmenu right placelist Topic alternative r
118. a macro draw_dot The current step will be highlighted in red using stand_out startbuffer b MISS bl WW 5 UW P Sem E djs 2 pickup pencircle scaled w def draw_dot expr p draw p withpen pencircle scaled 3w enddef def stand_out drawoptions withcolor 625red A few applications Page 520 Growing graphics enddef stopbuffer First we construct the macro that will plot two points A and B and connect them with a line segment startbuffer c def draw_basics pair pointA pointB path lineAB pointA origin pointB pointA shifted 5u 0 lineAB pointA pointB draw lineAB draw_dot pointA label 1lft btex A etex pointA draw_dot pointB label rt btex B etex pointB enddef stopbuffer The code in this buffer executes the preceding macros The _everything commands are still undefined but later we can use these hooks for special purposes startbuffer 1 start_everything stand_out draw_basics stop_everything stopbuffer This graphic can now be embedded by the CONTEXT command processMPbuffer This command like the ordinary buffer inclusion commands accepts a list of buffers content index reference Page 521 Growing graphics startlinecorrection blank ruledhbox processMPbuffer a b c 1 stoplinecorrection We use ruledhbox to show the tight bounding box of the graphic The line correction takes care of proper spacing around non textual con
119. a semi colon So when the content of the vardef is expanded we get something draw some_picture Because we are still drawing something we can add transform directives and set attributes like the color The second for loop demonstrates two nice features Instead of repeating the draw operation by copying code we apply it to a list in our case a list of paths This list contains two simple line paths Because an image starts with a fresh currentpicture we can safely use the bounding box data to determine the height of the line The next step in producing the sheets of paper is to put several bars on a page preferable with the width of the current text This time we will use a reusable graphic because each bar is the same startreusableMPgraphic bars includeMPgraphic bar draw MusicBar TextWidth 6pt 1pt 2pt withcolor 625yellow stopreusableMPgraphic content index reference Page 545 The euro symbol Instead of going trough the trouble of letting metarost calculate the positions of the bars we will use TEx We put 12 bars on a page and let Tpx take care of the inter bar spacing Because we only want stretchable space between bars called glue in T x we need to remove the last added glue startstandardmakeup doublesided no page dorecurse 10 reuseMPgraphic bars vfill removelastskip stopstandardmakeup It may add to the atmosphere of handy work if you slightly randomize the lines We leave it up
120. a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and Clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font even Page 291 Crossing borders Edward R Tufte We thrive in information thi
121. accomplished with withcolor 5 red green Since only the RGB color space is supported this is about all we can tell about colors for this moment Later we will discuss some nasty details Dashes A dash pattern is a simple picture that is build out of straight lines Any slightly more complicated picture will be reduced to straight lines and a real complicated one is rejected and in this respect METAPOST considers a circle to be a complicated path Welcome to MetaPost Page 73 Dashes The next example demonstrates how to get a dashed line First we built picture p that we apply to a path Here we use a straight path but dashing can be applied to any path picture p p nullpicture addto p doublepath 0 0 3mm 3mm shifted 6mm 6mm draw 0 0 10cm 0 dashed p withpen pencircle scaled 1mm This way of defining a pattern is not that handy especially if you start wondering why you need to supply a slanted path Therefore MeTAPOST provides a more convenient mechanism to define a pattern picture p p dashpattern on 3mm off 3mm draw 0 0 10cm 0 dashed p withpen pencircle scaled 1mm Most dashpatterns can be defined in terms of on and off This simple on off dashpattern is predefined as picture evenly Because this is a picture you can and often need to scale it draw 0 0 10cm 0 dashed evenly scaled 1mm withpen pencircle scaled 1mm Opposite to a defaultpen there is no default color and de
122. ackground left page setupbackgrounds rightpage background right page Now we only have to split the previously defined graphic into two parts In order to force consistency we isolate the code that fills and draws The left page code looks like startreusableMPgraphic left page StartPage path Main Main llcorner Field OuterMargin Text lrcorner Field Text Text urcorner Field Text Text ulcorner Field OuterMargin Text content index reference We thrive in information thick worlds because of our marvelous and everyday capacity to select ledit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into idealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chunk average approximate cluster aggregate outline sum Imarize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus I came to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not
123. acro NAI ath urmoved numeric fullcircle urmoved 25 metafun macro ath ulmoved numeric fullcircle ulmoved 25 metafun macro S content index reference ath Ilmoved pair N ath Irmoved pair ath urmoved pair Reference Page 618 Transformations fullcircle llmoved 1 25 metafun macro fullcircle lrmoved 1 25 metafun macro fullcircle urmoved 1 25 metafun macro Page 619 Transformations ath ulmoved pair fullcircle ulmoved 1 25 ath slanted numeric fullcircle slanted 5 metapost primitive metafun macro ath rotated numeric fullsquare rotated 45 metapost primitive content index reference Page 620 Transformations ath rotatedaround pairnumeric fullsquare rotatedaround 25 5 45 metapost macro fullcircle reflectedabout 25 1 25 1 metapost macro r reverse fullcircle shifted 5 0 metapost primitive Reference Cc ounterclockwise path tensepath path S ubpath numeric numeric of path counterclockwise fullcircle shifted 5 0 metapost macro tensepath fullcircle metapost macro subpath 1 5 of fullcircle metapost primitive content index reference Page 622 Transformations path cutbefore pair fullcircle cutbefore point 3 of fullcircle metapost macro path cutafter pair fullcircle cutafter point 3 of fullcircle metapost macro fullcircle cutends metapost macro
124. agraph When MeTAPOST sees a btex command it will consult a so called mpx file This file holds the Metarost rep resentation of the text typeset by Tpx Before meTAaPosT processes a graphic definition file it first calls another program that filters the btex commands from the source file and generates a Tpx file from them This file is then processed by Tx and after that converted to a mpx file In CONTEXT we let TEXEXEC take care of this whole process Because the btex etex commands are filtered from the raw metarostT source code they cannot be part of macro definitions and loop constructs When used that way only one instance would be found while in practice multiple instances may occur This drawback is overcome by METAFUN s textext command This command still uses btex etex but writes these commands to a separate job related file each time it is used After the first METAPOST run this file is merged with the original file and metarost is called again So at the cost of an additional run we can use text typeset by Tpx in a more versatile way Because METAPOST runs are much faster than Tpx runs the price to pay in terms of run time is acceptable Unlike btex etex the TeX code in textext command is expanded but as long as CONTpXT is used this is seldom a problem because most commands are somewhat protected If we define a graphic with text to be typeset by Tpx there is a good chance that this text is not frozen but pas
125. aled 1 5 metafun macro curved path curved 0 0 2 1 1 2 cycle metafun macro Reference laddered path ath paralleled distance Reference Page 604 Paths iladdencdi OsO Ginaer Ss mornin Gnome metafun macro 0 0 5 1 paralleled 25 metafun macro shortened path 0 0 6 1 shortened 1 metafun macro unspiked path unspiked 0 0 1 0 1 1 2 1 1 1 0 1 metafun macro simplified path simplified 0 0 1 0 2 0 2 1 0 1 cycle metafun macro content index reference ath blownup numeric pair fullcircle scaled 1 5 blownup 1 metafun macro ath stretched numeric pair fullcircle scaled 1 5 stretched 1 1 0 8 metafun macro Reference Reference Page 607 Paths roundedsquare 2 1 2 metafun macro tensecircle 2 1 2 metafun macro air crossed size origin crossed 1 metafun macro ath crossed size fullcircle scaled 2 crossed 5 metafun macro content index reference Transformations ath scaled numeric ath xscaled numeric ath yscaled numeric Reference fullcircle scaled 50 metapost primitive fullcircle xscaled 25 metapost primitive fullcircle yscaled 25 metapost primitive Page 610 Transformations ath zscaled pair fullcircle zscaled 2 25 a 2A metapost primitive ath xyscaled numeric pair fullcircle xyscaled 5 7 metapost primitive
126. and black component fill fullsquare xyscaled 10cm icm withcolor cmyk 1 0 3 3 content index reference Page 218 Communicating color 1 0 0 625 0 0 MPcolor red MPcolor darkred 625 MPcolor red Figure 3 4 Some kinds of red If you take a close look at the numbers you will notice that the cyan component results in a 100 ink contri bution You will also notice that 30 black ink is added This means that we cannot safely convert this color to RGB r 1 c k lt 0 without losing information Nevertheless the previous blue bar is presented all right This is due to the fact that in METAFUN the CMYK colors are handled as they should even when metarost does not support this color model If you use this feature independent of CONTEXT you need to enable it by setting cmykcolors to true You have to convert the resulting graphic to PDF by using for instance the mptopdf suite In CONTEXT you can influence this conversion by changing parameters related to color handling setupcolors cmyk yes mpcmyk no Embedded graphics Unless you know what you are doing you don t have to change the default settings both yes In the CONTEXT reference manual you can also read how color reduction can be handled Special care should be paid to gray scales Combining equal quantities of the three color inks will not lead to a gray scale but to a muddy brown shade fill fullsquare xyscaled 10cm 2cm withcolor 5white
127. and buttons Page 316 Graphic variables lrcorner cp shifted 0 ypart lrcorner cp urcorner cp ulcorner cp cycle fi endgroup stopuseMPgraphic Graphic variables In the previous sections we have seen that we can pass information to the graphic by means of variables How exactly does this mechanism work A nice application of setting up variables for a specific graphic or class of graphics is the following In an email message the author can express his own or the readers expected emotions with so called smilies like gt If you want them in print you can revert to combinations of characters in a font but as a TEX user you may want to include nicer graphics A convenient way to implement these is to make them into symbols one reason being that in that case they will adapt themselves to the current font size Say it with a symbol smile or maybe even a symbol smilemore although seeing too many dorecurse 10 symbol smile unskip in one text may make you cry Say it with a 5 or maybe even a 3 although seeing too many 5995 9d Because we want an efficient implementation we will use unique graphics because these will only be gener ated when the circumstances change content index reference Page 317 Graphic variables definesymbol smile uniqueMPgraphic smile type 1 definesymbol smilemore uniqueMPgraphic smile type 2 The definition itself then becomes setupMPvariables smi
128. andled with an additional condition and the offset with the METAFUN macro enlarged newinternal freelabeloffset freelabeloffset 3pt vardef thefreelabel expr str loc ori save s p q l picture s path p q pair l interim labeloffset freelabeloffset s if string str thelabel str loc else str shifted center str shifted loc fi setbounds s to boundingbox s enlarged freelabeloffset p fullcircle scaled 2 length loc ori shifted ori q freesquare xyscaled urcorner s llcorner s 1 point xpart p intersectiontimes ori loc of q setbounds s to boundingbox s enlarged freelabeloffset s shifted 1 enddef A few applications Page 486 Free labels Watch how we temporarily enlarge the bounding box of the typeset label text We will now test this macro on a slightly rotated circle using labels typeset by Tpx The reverse is there purely for cosmetic reasons to suit the label texts funny macros defining Can t we and on goon pickup pencircle scaled imm path p p reverse fullcircle rotated 25 scaled 3cm draw p withcolor 625yellow pair cp cp center p freedotlabel btex strut We can etex point 0 of p cp freedotlabel btex strut go on etex point 1 of p cp freedotlabel btex strut and on etex point 2 of p cp freedotlabel btex strut in etex point 3 of p cp freedotlabel btex strut defining etex point 4 of p cp freedotlabel btex strut
129. aphics In addition to the beginfig endfig method there are other ways to define and include a metapost graphic Each method has its advantages and disadvantages In the previous chapter we were still assuming that the graphic was defined in its own file In this chapter we will introduce the interface between CONTEXT and metAPOST and demonstrate how the definitions of the graphics can be embedded in the document source Getting started From now on we will assume that you have CONTEXT running on your platform Since PDF has full graphics support we also assume that you use LUATEX in combination with CONTEXT MKIV although most will also work with other engines and MKII Since this document is not meant as a CONTEXT tutorial we will limit this introduction to the basics needed to run the examples A simple document looks like starttext Some text stoptext You can process this document with the LUA based command line interface to CONTEXT If the source code is embedded in the file mytext tex you can say context mytext Embedded graphics Page 201 External graphics We will use color and in MKIV color is enabled by default If you don t want color you can tell CONTEXT so setupcolors state stop starttext Some color blue text and or color green graphics stoptext comes out in black and white In later chapters we will occasionally see some more CONTEXT commands show up If you want to know more about
130. ar way using the predefined path diamond startMPclip diamond clip currentpicture to unitdiamond xscaled width yscaled height stopMPclip The definition of the negated ellipse negellipse uses the primary peepholed This primary is defined in one of the mMETAPOsT modules that come with CONTEXT Special effects startMPclip negellipse clip currentpicture to unitcircle peepholed unitsquare xscaled width yscaled height stopMPclip The definition of peepholed is rather dirty and using peepholed is restricted to well defined situations like here It s called a primary because it acts as an operator at the same level as and scaled bea urellipse ulellipse llellipse lrellipse ellipse negellipse tellipse bellipse lellipse rellipse gt NP Dis urtriangle ultriangle Iltriangle Irtriangle diamond _negdiamond Figure 8 8 A collection of predefined clipping paths content index reference Page 350 Including graphics Including graphics This document demonstrates that it is no big problem to include metarost graphics in a TeX document But how about including graphics in a METAPOST picture In this section we will explore a couple of macros that provide you this feature Before we go into details we introduce a very impressive program called PSTOEDIT by Wolfgang Glunz This program runs on top of GHOSTSCRIPT and is able to convert POSTSCRIPT code into other formats among them METAPOST that part of the
131. available for CONTgXT users The text is typeset in Palatino and Computer Modern Typewriter We used LUATPX as TgX processing engine Since this document is meant to be printed in color some examples will look sub optimal when printed in black and white Graphics The artist impression of one of Hasselts canals at page 358 is made by Johan Jonker The CDROM production process graphic at page 351 is a scan of a graphic made by Hester de Weert Copyright Hans Hagen PRAGMA Advanced Document Engineering Hasselt NL copyright 1999 2010 version 2 October 8 2010 Page 656 Distributions Publisher publisher Boekplan NL isbn ean 978 94 90688 02 8 website www boekplan nl Info internet www pragma ade com support ntg context nte nl context www contextgarden net
132. background is white but you can set predefined color variables to another value path p p fullcircle scaled 2cm fill p shifted Ocm 0 fill p shifted 3cm 0 fill p shifted 6cm 0 fill p shifted 9cm 0 withcolor withcolor withcolor withcolor blue 5blue transparent 1 0 5 blue 5 blue white The next series demonstrates that we use the complementary factor 7 in the metarost soft color to achieve the same softness as the 3 transparency path p p fullcircle scaled 2cm fill p shifted Ocm 0 fill p shifted 3cm 0 fill p shifted 6cm 0 fill p shifted 9cm 0 Special effects withcolor withcolor withcolor withcolor red fred transparent 1 0 3 red 7 red white So far we have applied transparent colors to shapes but text can also be the target The following works okay in MKII vardef SampleText expr t c save p picture p p image draw t infont truefontname Regular draw p shifted xpart center p 0 scaled 5 withcolor c enddef SampleText Much Of This transparent 1 red SampleText Functionality transparent 1 5 green SampleText Was Written transparent 1 blue SampleText While Listening transparent 1 cmyk 1 0 0 0 SampleText To the CD s Of transparent 1 5 cmyk 0 1 0 0 SampleText Tori Amos transparent 1 5 cmyk 0 0 1 0 The source code of this example illustrates that the C
133. boundary round rt simplified sin sind sinh sqr sqrt stroked tan tand textpart textual top topboundary ulcorner uniformdeviate unitvector unknown unspiked urcorner xpart xxpart xypart yellowpart ypart yxpart yypart type boolean color cmykcolor numeric pair path pen picture rgbcolor string transform primary binop and dotprod div infont mod METAPOST syntax Page 567 Syntax diagrams secondary binop gt tp cee sr ore intersectionpoint intersectiontimes tertiary binop gt amp lt lt lt gt gt gt cutafter cutbefore cutends of operator arctime direction directiontime directionpoint penoffset point postcontrol precontrol subpath substring variable tag suffix suffix empty suffix subscript suffix tag suffix parameter subscript number numeric expression METAPOST syntax Syntax diagrams internal variable ahangle ahlength bboxmargin charcode day defaultcolormodel defaultpen defaultscale hour labeloffset linecap linejoin minute miterlimit month outputformat outputtemplate pausing prologues showstopping time tracingoutput tracingcapsules tracingchoices tracingcommands tracingequations tracinglostchars tracingmacros tracingo
134. bounds currentpicture to boundingbox currentpicture enlarged 2pt content index reference Killing time Not seldom Tpx users want to use this program and its meta relatives as general purpose tools even at the cost of quite some effort or suboptimal results Imagine that you are under way from our planet to Mars After a long period of sleep you wake up and start wondering on what track you are You even start questioning the experts that send you on your way so you pop open your laptop launch your editor and start metaposting First you need to determine the begin and end points of your journey For this it is enough to know the relative angle of the paths that both planets follow as well as the path themselves We assume circular paths path a a fullcircle scaled 3cm path b b fullcircle scaled 2cm rotated 120 draw a withpen pencircle scaled 1mm withcolor 625red draw b withpen pencircle scaled 1mm withcolor 625yellow draw point 0 of a withpen pencircle scaled 2mm draw point 0 of b withpen pencircle scaled 2mm The rotation 120 can be calculated from the relative starting points and time the journey will take Alternatively we can use the time along the path but this would be a bit more fuzzy later on 16 In case you wonder why metarost talks about the time on a path you now have a cue content index reference After a bit of playing with drawing paths between the two points you decide to make
135. but the related variables x and y Welcome to MetaPost Next we draw four squares and instead of hard coding their corner points we use METAPOST s equation solver Watch the use of which means that we just state dependencies In languages like PERL the equal sign is used in assignments but in METAPOST it is used to express relations Ina first version we will just name a lot of simple relations as we can read them from a sketch drawn on paper So we end up with quite some z related expressions For those interested in the mathematics behind this code we add a short explanation Absolutely key to the construction is the fact that you traverse the original quadrilateral in a clockwise orientation What is really going on here is vector geometry You calculate the vector from 211 to Z12 the first side of the original quadrilateral with a b 212 z11 This gives a vector that points from Z1 to Z12 Now how about an image that shows that the vector b a is a 90 degree rotation in the counterclockwise direction Thus the points z 3 and Zy4 are easily calculated with vector addition zi3 z12 b a zi4 z11 b a This pattern continues as you move around the original quadrilateral in a clockwise manner The code that calculates the pairs a through h can be written in a more compact way a b z12 z11 c d z22 221 e f 232 231 g h 242 241 Thanks to David Arnold for t
136. by a lioness It is still unclear if they have a relationship but if so and if a baby is born may it enjoy METAFUN The low level CONTEXT macro processwords provides a mechanism to treat the individual words of its argu ment The macro is called as follows processwords As you may know TEX s ambassador is a lion while METAFONT is represented by a lioness It is still unclear if they have a relationship but if so and if a baby is born may it enjoy METAFUN In order to perform a task you should also define a macro processword which takes one argument The previous quote was typeset with the following definition in place def processword 1 1 A slightly more complicated definition is the following def processword 1 noindent framed 1 space Enhancing the layout Page 235 Typesetting graphics We now get As you may know TgxX s ambassador jisi a lion ile METAFONT is represented lioness It jis Istill unclear if they havel la relationship if jso jand if a baby lis enjoy METAFUN may lit If we can use framed we can also use backgrounds def processword 1 noindent framed frame off background lions 1 We can add a supper
137. can use the small Tex package MPTOPDF described in another manual or you can make small CONTEXT files with one page graphics The advantage of the last method is that you can manipulate graphics a bit setupcolors cmyk yes rgb no state start starttext startMPpage Loffset 6pt loadfigure niceone mp number 10 stopMPpage content index reference Page 355 Changing colors stoptext The resulting PDF file can be included as any other graphic and has the advantage that it is self contained Changing colors One of the advantages of metarost graphics is that it is rather easy to force consistency in colors and line widths You seldom can influence third party graphics that way but we can use some METAFUN trickery to get around this limitation Say that we want a red cow instead of a black one The following code does the trick loadfigure mycow mp number 1 scaled 35 refill currentpicture withcolor 625red Ina similar way we can influence the width and colors of the lines Special effects Page 356 Changing colors loadfigure mycow mp number 1 scaled 35 refill currentpicture withcolor 625red redraw currentpicture withpen pencircle scaled 2pt withcolor 625yellow Of course we can also use the more fancy features of METAFUN like transparency and shading loadfigure mycow mp number 1 scaled 35 numeric sh sh define linear_shade 1lcorner currentpicture urcorner currentpicture 625red 62
138. ck worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose Le Gee list abstract scan look into enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus Icame to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and
139. cm 0 squeezed 5cm drawpath p drawpoints p A punked path is like a punked font a font with less smooth curves in our case only straight lines path p p fullcircle scaled 2cm randomized 5cm drawpath p drawpoints p p punked p shifted 5cm 0 drawpath p drawpoints p Welcome to MetaPost Page 96 Some extensions A curved path on the other hand has smooth connections Where in many cases a punked path becomes smaller a curved path will be larger path p p fullsquare scaled 2cm randomized 5cm drawpath p drawpoints p p curved p shifted 5cm 0 drawpath p drawpoints p Probably less usefull although we use it in one of the OPENTYPE visualizers is laddered path p p fullcircle scaled 3cm drawpath p drawpoints p p laddered p shifted 5cm 0 drawpath p drawpoints p Welcome to MetaPost Page 97 Some extensions When writing PPCHTgx that can be used to draw chemical structure formulas I needed a parallelizing macro so here it is path p p fullcircle scaled 3cm drawpath p drawpoints p p p paralleled icm drawpath p drawpoints p If you use a negative argument like 1cm the parallel line will be drawn at the other side Welcome to MetaPost Page 98 Some extensions The blownup operation scales the path but keeps the center in the same place path p p fullsquare xyscaled 4cm 1cm randomized 5cm drawpat
140. cow mps width 4cm Clipping is combined with a matrix as in figure 8 3 The content to be clipped is divided in nx by ny rectangles For instance nx 5 and ny 8 will produce a 40 cell grid with 5 columns of 8 rows Special effects exit KIKD Page 343 Clipping figure 8 4 n Figure 8 4 Another clipped cow Special effects Page 344 Clipping placefigure here fig clipped cow 2 Another clipped cow clip width 2cm height 2cm hoffset 0cm voffset 0cm externalfigure cow mps width 4cm Because METAPOST supports clipping it will be no surprise that both techniques can be combined In the next example we will zoom in on the head of the cow We also use this opportunity to demonstrate how you can package a clip in a figure definition startMPclip head clip w width h height clip currentpicture to O h w h down left 0 0 cycle stopMPclip placefigure here fig circular clipped cowhead A quarter circle applied to a cows head ruledhbox clip nx 2 ny 2 x 1 y 1 mp head clip externalfigure cow mps width 4cm A more advanced clip is demonstrated in figure 8 5 We added ruledhbox to demonstrate the dimensions of the resulting graphic Putting something in such a ruled box is often a quick way to test spacing Special effects Page 345 Clipping Special effects Page 346 Clipping align middle width 4cm background screen frame off A METAP
141. creen 8 framed background circle framed background color cow backgroundcolor red framed background color cow grid backgroundcolor red In the last three cases of course you have to define circle cow and grid as overlay These items are packed in a comma separated list which is to be surrounded by Foregrounds The overlay system is actually a system of layers Sometimes we are confronted with a situation in which we want the text behind another layer This can be achieved by explicitly placing the foreground layer as in figure 4 3 frame on top layer frame on bottom layer Figure 4 3 Foreground material moved backwards The graphic layer is defined as follows Enhancing the layout Page 232 Foregrounds startuniqueMPgraphic backfore draw fullcircle xscaled overlaywidth yscaled overlayheight withpen pencircle scaled 2pt withcolor 625yellow stopuniqueMPgraphic defineoverlay backfore uniqueMPgraphic backfore The two framed texts have a slightly different definition The leftmost graphic is defined as framed background backfore backgroundoffset 4pt fone two three unknown The rightmost graphic is specified as framed background foreground backfore backgroundoffset 4pt fone two three unknown The current values of the frame color and frame width are passed to the overlay It often makes more sense to use colors defined at the document level if o
142. cros We can decompose METAPOST pictures using a within loop You may wonder if such a within loop construct has any real application and as you can expect it has In section 13 4 a macro is defined that draws a colored A few more details Page 183 Analyzing pictures circle If you want the inverted alternative you can pass the inverted color specification but wouldn t it be more convenient if there was an operator that did this for you automatically Unfortunately there isn t one so we have to define one ourselves in a macro These circles were drawn using colorcircle 4cm 4 6 8 4 8 6 6 4 8 addto currentpicture also inverted currentpicture shifted 5cm 0 When we draw a path or stroke a path as it is called officially we actually perform an addition addto currentpicture doublepath somepath The fill command is actually addto currentpicture contour somepath content index reference We will need both doublepath and contour operations in the definition of inverted When metarost has digested a path into a picture it keeps track of some characteristics We can ask for them using part operators The following operators can be applied to a transform vector one of METAPOST Ss data types but also to a picture Say that we have drawn a circle draw fullcircle xscaled 3cm yscaled 2cm dashed dashpattern on 3mm off 3mm withpen pencircle scaled imm withcolor 625red picture p p curren
143. currently cannot store external figures in picture variables in order to transform them afterwards Special effects Page 352 Including graphics Although you are limited in what you can do with such graphics you can include them multiple times with a minimum of overhead Graphics are stored in objects and embedded only once numeric s pair d c ie a s il mo S 2 s 3cm randomized icm size of picture s Da 3 center of picture d 2cm i 5cm randomized 5cm displacement externalfigure hacker png scaled s rotatedaround c 0 randomized 30 shifted d endfor Because we cannot store the graphic in a picture and scale afterwards we calculate the scale in advance so that we can rotate around the center Special effects Page 353 Including graphics As long as you don t mess around with a stored external figure you re safe The following example demon strates how we can combine two special driven features figure inclusion and shading picture p p image externalfigure hacker png scaled 150pt clip p to unitcircle scaled 150pt circular_shade boundingbox p enlarged 10pt 0 2red 9red addto currentpicture also p content index reference Page 354 Including graphics We end this section with a few more words to meTaPosT inclusion It may seem that in order to use the features discussed here you need to use CONTEXT as typesetting engine This is not true First of all you
144. d by the top and 1 t directives If we would not have clipped the picture the arrow would have stuck half a line width outside the gray area that represents the page When constructing such pictures one should really pay attention to such details since it pays off in the overall look and feel of the document content index reference The vertical arrow represents the top space while the horizontal arrow denotes the distance to the back of the cover back space By changing their values you can shift the main body text on the page In a double sided layout scheme the back space is automatically mirrored on even pages Since we want to teach a bit of MeTarost now and then we will also show how these graphics were drawn An advanced mMeTAPOST user may wonder why we hard code the dimensions and avoid mMetarost s powerful mechanisms for defining relations Our experience has taught us that in pictures like this providing a general solution seldom pays large dividents or savings in time startuseMPgraphic layout 1 pickup pencircle scaled imm fill unitsquare xyscaled 7cm 8cm withcolor 85white fill unitsquare xyscaled 5cm 5cm shifted 1cm 1 5cm withcolor 625yellow fill unitsquare xyscaled 5cm icm shifted 1cm 5cm withcolor 625red fill unitsquare xyscaled 5cm icm shifted 1cm 6 5cm withcolor 625red draw unitsquare xyscaled 5cm 7cm shifted 1cm 5cm withcolor 25white drawarrow 2cm 8cm top 2cm 7 5cm
145. decided to label this style as pre organic If you use CONTgXT you can load this style with usemodule pre organic At the end of this file there is a small test file so when you process the file s pre 19 tex with the options mode demo and pdf you will get a demo document We use one of the standard screen paper sizes and map it onto the same size so that we get a nicely cropped page Other screen sizes are 4 and S5 setuppapersize S6 S6 Like in this METAFUN manual we use the Palatino as main bodyfont This font is quite readable on even low resolution screens although I admit that this style is developed using an 1400 x 1050 pixel LCD screen so the author may be a little biased setupbodyfont pp1 The layout specification sets up a text area and a right edge area where the menus will go see chapter 6 fora more in depth discussion on the layout areas Watch how we use a rather large edge distance By setting the header and footer dimensions to zero we automatically get rid of page body ornaments like the page number This style is the 19 presentation style Those numbered styles are internally mapped onto more meaningful names like in this case pre organic Defining styles Adaptive buttons setuplayout topspace 48pt backspace 48pt cutspace 12pt width 400pt margin Ocm rightedge 88pt rightedgedistance 48pt header 0cn footer 0cn height middle We use a moderate about
146. definitions also point out why you cannot add directives to the left or right side of and they are directives themselves Transformations A transform is a vector that is used in what is called an affine transformation To quote the METAPOST manual If p px py is a pair and T is a transform then p transform T is a pair of the form tx txxpx bxyPyty tyxPx tyypy where the six numeric quantities t ty tuxtxytyxty determine T In literature concerning POSTSCRIPT and PDF you will find many references to such transformation matrices A matrix of 5 0 0 s 0 0 is scaling by sy in the horizontal direction and s in the vertical direction while 1 0 t 1 0 ty is a shift over t ty Of course combinations are also possible Although these descriptions seem in conflict with each other in the nature and order of the transform compo nents in the vectors the concepts are the same You normally populate transformation matrices using scaled shifted rotated transform t t identity shifted a b rotated c scaled d path p p fullcircle transformed t The previous lines of code are equivalent to path p p fullcircle shifted a b rotated c scaled d A few more details Page 164 Transformations You always need a starting point in this case the identity matrix identity 0 0 1 0 0 1 By the way in POST SCRIPT the zero vector is 1 0 0 1 0 0 So unless you want to extract the components using
147. doublescaled 2cm withcolor red When this command is executed the macro is expanded Thus the actual content of this command becomes draw somepath xscaled icm yscaled 4cm withcolor red If in the definition of doublescaled we had added a semi colon after s 2 we could not have set the color because the semicolon ends the statement The draw expects a path so the macro can best return one A macro can take one or more arguments as in def drawrandomscaledpath expr p s draw p xscaled s 2 yscaled s 2 enddef Welcome to MetaPost Page 59 Macros When using this macro it is expected that you will pass it two parameters the first being a path the second a numeric scale factor drawrandomscaledpath fullsquare 3cm Sometimes we want to return a value from a macro In that case we must make sure that any calculations don t interfere with the expectations Consider vardef randomscaledpath expr p s numeric r r round 1 uniformdeviate 4 p xscaled s r yscaled s r enddef Because we want to use the same value of r twice we have to use an intermediate variable By using a vardef we hide everything but the last statement It is important to distinguish def macros from those defined with vardef In the latter case vardef macros are not a simple expansion and replacement Rather vardef macros return the value of their last statement In the case of the randomscaledpath macro a path is returned
148. drawarrow anglebetween c d btex gamma etex drawarrow anglebetween e f btex epsilon etex anglelength 1 5cm drawoptions withcolor 625yellow drawdblarrow anglebetween b c btex beta etex drawarrow reverse anglebetween d e btex delta etex drawarrow anglebetween a f btex zeta etex Because anglebetween returns a path you can apply transformations to it like reversing Close reading of the previous code learns that the macro handles both directions A few applications Page 495 Marking angles Multiples of 90 degrees are often identified by a rectangular symbol We will now extend the previously defined macro in such a way that more types can be drawn numeric anglelength anglelength 20pt numeric anglemethod anglemethod al vardef anglebetween expr a b str path path string save pointa pointb common middle offset pair pointa pointb common middle offset save curve path curve save where numeric where if round point O of a round point O of b common point O of a elses common a intersectionpoint b fin pointa point anglelength on a pointb point anglelength on b where turningnumber common pointa pointb cycle middle common pointa rotatedaround pointa where 90 intersectionpoint common pointb rotatedaround pointb where 90 if anglemethod 1 curve pointa unitvector middle pointa pointb middle point 5 along cu
149. drawarrow reverse p shifted 2cm 0 drawarrow counterclockwise p shifted 4cm 0 drawarrow counterclockwise reverse p shifted 6cm 0 drawarrow reverse counterclockwise p shifted 8cm 0 Doo TS Only this far When you take a close look at the definitions of the Computer Modern Roman fonts defined in the METAFONT book you will notice a high level of abstraction Instead of hard coded points you will find points defined in terms of being the same as this point or touching that point In this section we will spend some time on this touchy aspect A few more details This rectangle is a scaled instance of the predefined METAFUN path fullsquare which is centered around the origin pickup pencircle scaled 2mm path p p fullsquare scaled 2cm draw p withcolor 625white On this path halfway between two of its corners we define a point q pair q q 5 llcorner p lrcorner p We draw this point in red using draw q withcolor 625red As you can see this point is drawn on top of the path There are four of those midpoints and when we connect them we get A few more details Page 170 Only this far O NZ Because path p is centered around the origin we can simply rotate point q a few times draw q q rotated 90 q rotated 180 q rotated 270 cycle withcolor 625red There are situations where you don t want the red path to be drawn inside another path or more general where
150. drawpoints p drawpath q drawpoints q resetdrawoptions 2 content index reference Page 103 Some extensions As with more operators cutends accepts a numeric or a pair Watch the subtle difference between the next and the previous use of cutends path p p Ocm 0 4cm 0 8cm 0 4cm 0 cycle drawpath p drawpoints p p p cutends 2cm icm drawpathoptions withpen pencircle scaled 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4pt withcolor 625red drawpath p drawpoints p resetdrawoptions When stretched is applied to a path it is scaled but the starting point point 0 keeps its location The speci fication is a scale path p p Ocm 0 3cm icm 4cm 0 5cm 1cm drawpath p drawpoints p p p stretched 1 1 drawpathoptions withpen pencircle scaled 2 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4 0pt withcolor 625red drawpath p drawpoints p resetdrawoptions Welcome to MetaPost Page 104 Some extensions We can scale in two directions independently or even in one direction by providing a zero value In the next example we apply the stretch two times path p p Ocm 0 3cm icm 4cm 0 Scm icm drawpath p drawpoints p p p stretched 75 1 25 drawpathoptions withpen pencircle scaled 2 5pt withcolor 625yellow drawpointoptions withpen pencircle scaled 4 0pt withcolor 625r
151. e available too Later we will discuss Metarost capability to deal with expressions which are expressed using an instead of In this case the expression related to z0 is expanded into z0 x0 y0 0 5cm 1 5cm But for this moment let s forget about their expressive nature and simply see them as points which we will now connect by straight line segments WAV a F FA CV ELLS The smooth curved connection using looks like Welcome to MetaPost Page 26 Constructing paths wz Orez oA oFABo Cy e lek Since there are and it will be no surprise that there is also Welcome to MetaPost Page 27 Constructing paths z0 ZI ZO cycle If you compare this graphic with the one using the result is the same but there is a clear difference in control points As a result combining with or makes a big difference Here we get a non smooth connection between the curves and the straight line NAD zi Z2 Z3 cyclen As you can see in the next graphic when we use we get a smooth connection between the straight line and the rest of the curve Welcome to MetaPost Page 28 Constructing paths N A 5 otk a I 48 5 CVE So far we have joined the four points as one path Alternatively we can constrict subpaths and connect them using the ampersand symbol amp NA 5 Fils 2B I 22 3 AD bs eyele So far we have created a closed path Closing is done by cycle The followi
152. e mentioned that a pair or point can specify a direction or vector Although any angle is possible we often use one of four predefined directions right 1 0 up 0 1 ieee il down C O We can use these predefined directions in combination with directionpoint and cutafter The following command locates the first point on the path that has a tangent that points vertically upward and then feeds this point to the cutafter command z1 cycle cutafter directionpoint up of z0 z1 cycle You are not limited to predefined direction vectors You can provide a pair denoting a direction In the next example we use the following cyclic path Welcome to MetaPost Page 40 Constructing paths NAO oll o o GELS Using is not mandatory but makes the expression look less complicated zO z1 cycle cutafter directionpoint 1 1 of z0 z1 cycle We will apply these commands in the next chapters but first we will finish our introduction in Metarost We have seen how a path is constructed and what can be done with it Now it is time to demonstrate how sucha path is turned into a graphic Welcome to MetaPost 1 4 Angles You can go from angles to vectors and vice versa using the angle and dir functions The next example show both in action pickup pencircle scaled 2mm draw origin dir 45 dir 0 cycle scaled 3cm withcolor 625red draw origin dir angle 1 1 dir a
153. e a similar arrangement for the following graphic where we have replaced the definitions of first second and third by new definitions The definition of the first row of figure 13 4 is used in the second and third and therefore is the most compli cated We use quite some scratch variables to reach a high level of abstraction The xyscaled operator is a METAFUN macro startuseMPgraphic first height 2 5cm width height 2 radius height 2 5 color mainshade leftshade rightshade centershade mainshade MPcolor funcolor leftshade 9mainshade rightshade 5mainshade centershade 5 leftshade rightshade fill unitsquare xyscaled width height withcolor leftshade fill unitsquare xyscaled width height withcolor rightshade draw fullcircle scaled radius shifted 0 height 2 withpen pencircle scaled radius 2 withcolor centershade stopuseMPgraphic numeric height width radius gap gap 1mm The graphics of the second row extend those of the first by drawing a white line through the middle In this example setting the linecap is not really needed because rounded top and bottoms in white are invisible and the part that extends beyond the points does not count in calculating the bounding box A few applications Figure 13 4 Koffka s examples of manipulating contrast by changing the spatial configuration startuseMPgraphic second includeMPgraphic first content index reference i
154. e can be included in the normal way using externalfigure mprun 21 width 5cm Optionally you can specify a name and an instance This has the advantage that the graphics don t interfere with the regular inline graphics Here the instance used is extrafun and the name where the run is stored is mydemo Embedded graphics Figure 3 1 The logo is defined in the file mylogos mp as figure 21 and processed by means of the mprun method startMPrun mydemo input mfun mrun demo mp stopMPrun placefigure An external file can have multiple graphics Here we show a few images that we used to use on the PRAGMA CONTEXT website startcombination 2 2 externalfigure mprun extrafun mydemo 1 height 6cm downloads content index reference Page 211 Using METAFUN but not CONT XT externalfigure mprun extrafun mydemo 2 height 6cm links externalfigure mprun extrafun mydemo 3 height 6cm mirrors externalfigure mprun extrafun mydemo 4 height 6cm team stopcombination Keep in mind that the whole file will be processed using the built in library in order to get one graphic Normally this is no big deal Using METAFUN but not CONTEXT If you don t want to use CONTEXT but still want to use METAFUN a rather convenient method is the following Create a file that startMPpage Your mp code goes here You can use the textext macro as discussed later to deal with typeset text
155. e data itself so the foreground graphics end up on top This example also demonstrates that you should be well aware of the way CONTpXT builds a page There are six main layers in some cases with sublayers The body text goes into the main text layer which unless forced otherwise lays on top 1 paper background 3 page backgrounds 5 logo areas 2 area backgrounds 4 text areas 6 main text The paper background is used for special sometimes internal purposes There are three page backgrounds left right and both The text areas logo areas and backgrounds form a 5 x 5 matrix with columns containing the leftedge leftmargin text rightmargin and rightedge The rows of the matrix contain the top header text footer and bottom The main text is what you are reading now Since the page background is applied last the previous layers can considered to be the foreground to the page background layer And indeed it is available as an overlay under the name foreground as we already saw in the example Foregrounds are available in most cases but for the moment not when we are dealing with content index reference the text area Since anchoring the graphics is implemented rather independent of the position of the graphics themselves this is no real problem we can put them all on the page layer if needed in separate overlays How is such a graphic defined In fact these graphics are a special case of the already present mechanism of i
156. e details In order to save you some typing METAFUN provides a macro cutends that does the same job r r cutends 5pt This time we draw the path in a different order draw r withpen pencircle scaled 20pt withcolor 625white draw p withpen pencircle scaled 10pt withcolor 625red draw q withpen pencircle scaled 10pt withcolor 625yellow That way we hide the still remaining overlapping part of the line Directions Quite often you have to tell meTaPosT in what direction a line should be drawn A direction is specified as a vector There are four predefined vectors up down left right These are defined as follows A few more details pair up down left right up down 0 1 right left 1 0 We can use these predefined pairs as specifications and in calculations dotlabel top up up 1cm dotlabel bot down down icm dotlabel 1lft left left 1cm dotlabel rt right right 1cm drawoptions withpen pencircle scaled 25mm withcolor 625 red drawarrow origin up 1cm drawarrow origin down 1cm drawarrow origin left tem drawarrow origin right 1cm We down This graphic can also be defined in a more efficient but probably more cryptic way The next definition demonstrates a few nice tricks Instead of looping over the four directions we loop over their names In side the loop we convert these names or strings into a pair by scanning the string using scantoke
157. e of text ends up on its own page and afterwards it again calls a program that converts the DVI pages into METAPOST pictures In CONTEXT MKII when using WEB2C you can generate the graphics at run time This takes more time than processing the graphics afterwards but has the advantage that TeX knows immediately what graphic it is dealing with When enabled CONTEXT will call either MeTAPosT or when the graphic contains btex etex commands call T XEXEC which in turn makes sure that the right auxiliary programs are executed In CONTEXT MKIV you won t notice this at all as there everything is tightly integrated with LUATEX s MPLIB Typesetting in METAPOST Page 393 Environments TEXEXEC CONTEXT TEXEXEC CONTEXT Figure 10 1 How Tpx and metarost work together Environments In case you want to pass code that is shared by all btex etex pictures METAPOST provides verbatimtex DefineSomeCommands etex However in CONTEXT one has a better mechanism available In CONTEXT MKII the advised method is passing environments The best way to pass them is the following As an example we switch to the 15 basic POSTSCRIPT fonts startMPenvironment usetypescript palatino texnansi mkii has encodings setupbodyfont palatino stopMPenvironment This means that in code like the following a Palatino font will be used Typesetting in METAPOST startMPcode draw btex Meta is a female lion etex xysized the textwidt
158. e this point using the arctime primitive vardef somearrow expr pat loc len save p path p p pat cutbefore loc p cutafter point arctime len of p of p enddef By using a vardef we hide the intermediate assignments Such vardef is automatically surrounded by begingroup and endgroup so the save is local to this macro When processed this code produces the fol lowing graphic Welcome to MetaPost Page 112 Cutting and pasting This graphic shows that we need a bit more control over the exact position of the arrow It would be nice if we could start the arrow at the point or end there or center the arrow around the point Therefore the real implementation is a bit more advanced vardef pointarrow expr pat loc len off save 1 r s t path 1 r numeric s pairt if pair loc loc else point loc along pat fi len 2 off if s lt 0 s 0 elseif s gt len s pat cutbefore t r cutafter point arctime s of r of r len 2 off if s lt 0 s 0 elseif s gt len Ges Fen fi reverse pat cutafter t l reverse 1 cutafter point arctime s of 1 of 1 Gi enddef This code fragment also demonstrates how we can treat the loc argument as pair coordinates or fraction of the path We calculate the piece of path before and after the given point separately and paste them afterwards Welcome to MetaPost Page 113 Cutting and pasting as 1 r By adding braces we can manipulate the
159. eader this is not an easy chapter More layers Overlays are one of the nicer features of CONTEXT and even more nice things can be build on top of them Overlays are defined first and then assigned to framed boxes using the background variable You can stack overlays which is why they are called as such You can use the special overlay called foreground to move the topmost often text layer down in the stack background overlay a text graphic hyperlink or widget position overlay a series of macros triggered by positions background layer a box that can hold boxes with offsets The last kind of layer can be used in other situations as well but in most cases it will be hooked into a back ground overlay content index reference Page 263 More layers definelayer MyLayer option test setupbackgrounds text leftmargin background MyLayer setlayer MyLayer x 5cm y 5cm rotate framed This goes to the background In this case the framed text will be placed in the background of the current page with the given offset to the topleft corner Instead of a fixed position you can inherit the current position using the position directive Say that we have a layer called YourLayer which we put in the background of the text area definelayer YourLayer setupbackgrounds text text background YourLayer We can now move some framed text to this layer using setlayer with the directive position set to yes here
160. ean solution using subpath We will assume that the circle is called with the macro colorcircle 4cm red green blue We need to calculate seven paths The first implementation does all the handywork itself and thereby is rather long complicated and unreadable It does not really use the strenghth of MeTAPOST yet content index reference Page 498 Color circles vardef colorcircle expr size red green blue save r g b rr gg bb cc mm yy save bir b_g gr gb save radius path r g b rr bb gg cc mm yy pair b_r b_g gr gb numeric radius radius 3cm pickup pencircle scaled radius 20 g b fullcircle scaled radius shifted 0 radius 4 rotatedaround origin 15 drawarrow r withcolor red rotatedaround origin 135 drawarrow g withcolor green rotatedaround origin 255 drawarrow b withcolor blue b intersectionpoint 5 dran b r b intersectionpoint 4 draw bg reverse g intersectionpoint 4 draw gr reverse g intersectionpoint 4 draw gb b cutafter b_r bb bb cutbefore b_g drawarrow bb g cutbefore b_g gg gg cutafter gr drawarrow gg r cutbefore gr amp r cutafter b_r drawarrow rr content index reference Page 499 Color circles b cutbefore b_r cc cc cutafter gb drawarrow br g cutbefore gr yy yy cutafter gb 4 drawarrow rg r cutbefore gr amp r cutafter b_r drawarrow gb Be Tie TETS loo Gele
161. ection of such macros is available when you launch metarost Consult the meTarost manual for details E In the first line of our example we set the drawing pen to 5cm You can also specify such a dimension in other units like points pt When no unit is provided mMetarost will use a big point bp the POSTSCRIPT approximation of a point The second line does just as it says it draws a rectangle of certain dimensions in a certain color In the third line we draw a colored dot at the origin of the coordinate system in which we are drawing Finally we set up a smaller pen and draw the bounding box of the current picture using the variable currentpicture Normally all drawn shapes end up in this picture variable Bounding boxes If you take a close look at the last picture in the previous section you will notice that the bounding box is larger than the picture This is one of the nasty side effects of MeTAPOST s bbox macro This macro draws a box but content index reference Page 121 Bounding boxes with a certain offset The next example shows how we can manipulate this offset Remember that in order to process the next examples you should embed the code in beginfig and endfig macros Also in stand alone graphics don t forget to say input mp tool first pickup pencircle scaled 5cm draw unitsquare xscaled 8cm yscaled 1cm withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen
162. ed drawpath p drawpoints p p p stretched 0 1 5 drawpathoptions withpen pencircle scaled 4 0pt withcolor 625red drawpointoptions withpen pencircle scaled 2 5pt withcolor 625yellow drawpath p drawpoints p resetdrawoptions We already met the randomize operator This one is the chameleon under the operators Welcome to MetaPost Page 105 Some extensions draw fullsquare xyscaled 4cm 2cm randomized 25cm shifted origin randomized 1cm 2cm withcolor red randomized 625 850 withpen pencircle scaled 5pt randomized 1pt So randomized can handle a numeric pair path and color and its specification can be a numeric pair or color depending on what we re dealing with In the previous example we also see xyscaled in action Opposite to scaled xscaled and yscaled this is not one of mETAPOST build in features The same is true for the sized operators picture p p image draw fullsquare xyscaled 300 800 withpen pencircle scaled 50 withcolor 625 yellow draw p xysized 3cm 2cm shifted bbwidth currentpicture 5cm 0 Welcome to MetaPost Page 106 Some extensions draw p xysized 2cm shifted bbwidth currentpicture 5cm 0 draw p xsized tom shifted bbwidth currentpicture 5cm 0 draw p ysized 2cm shifted bbwidth currentpicture 5cm 0 PIO i Here the image macro creates an actually rather large picture The last four lines actually draw this picture but at
163. ed Some extensions 3 2 External graphics Content Integrated graphics Setting up backgrounds Using METAFUN but not CONTEXT s Multiple overlays Graphic buffers Crossing borders Communicating color Bleeding Common definitions One page graphics Shapes symbols and buttons Managing resources Interfacing to TEX Enhancing the layout Random graphics Graphic variables Overlays Shape libraries Overlay variables Symbol collections Stacking overlays Foregrounds Special effects Typesetting graphics Graphics and macros Shading Transparency Positional graphics Clipping Including graphics The concept Changing colors Anchors and layers Outline fonts More layers Complex text in graphics Functions Page backgrounds Overview The basic layout Drawing functions Content 10 Typesetting in METAPOST 10 1 The process 10 2 Environments 10 3 Labels 10 4 TX text 10 5 Talking to Tex 10 6 Libraries 11 Debugging 12 Defining styles 12 1 Adaptive buttons 13 A few applications 13 1 Simple drawings 13 2 Free labels 13 3 Marking angles 13 4 Color circles 13 5 Fool yourself 13 6 Growing graphics 13 7 Simple Logos 13 8 Music sheets 13 9 The euro symbol 13 10 Killing time 14 METAFUN macros Content A METAPOST syntax Syntax diagrams Left overs B This document C Reference Cl C 2 C3 C 4 C5 C 6 Transformations Points Attributes Graphics D Literature IDI D 2 D3 D4 D 5 Index
164. ed bbwidth currentpicture 5cm 0 content index reference Page 362 Changing colors By providing a triplet you can treat each color component independently loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture softened 7 8 9 shifted bbwidth currentpicture 5cm 0 content index reference Page 363 Outline fonts After these examples your are probably sick of seeing this picture in color so let s turn the colors into a weigthed grayscales in a way similar to the way black and white television treated color loadfigure gracht mp number 1 scaled 5 addto currentpicture also grayed currentpicture shifted bbwidth currentpicture 5cm 0 Outline fonts Outline fonts don t belong to MeTarosT s repertoire of features Nevertheless we can simulate this in a reason able way We will not discuss all details here because most details are covered in the MAKEMPY manual The macro responsible for outline fonts is graphictext The first argument should be a string This string is processed by Tpx Additionally you can provide transformation directives and color specifications The next example demonstrates this Special effects Page 364 Outline fonts graphictext bf Fun scaled 4 zscaled 1 1 5 withdrawcolor blue withfillcolor 5white withpen pencircle scaled 5pt Once the text is typeset by TEX it is converted to POSTSCR
165. ed when visualizing the bounding box and origin swappointlabels true path p p fullcircle xscaled 4cm yscaled 3cm drawarrowpath p drawcontrollines p drawpoints p drawcontrolpoints p drawpointlabels p drawboundingbox p draworigin In this example we have set swappointlabels to change the place of the labels You can set the variable originlength to tune the appearance of the origin Debugging Page 449 Libraries Here we used the options Debugging Page 450 Libraries path p p fullcircle xscaled 6cm yscaled 3cm rotated 15 drawarrowpath p drawcontrollines p withcolor 625red drawpoints p withcolor 625yellow drawcontrolpoints p withcolor 625yellow drawpointlabels p withcolor 625yellow drawboundingbox p draworigin withcolor 625red Sometimes it makes sense to draw a simple coordinate system and for that purpose we have three more macros They draw axis and tickmarks drawticks unitsquare xscaled 4cm yscaled 3cm shifted 1cm 1cm The system drawn is based on the bounding box specification of the path passed to the macro You can also draw one axis using drawxticks or drawyticks Here we show the previous command Debugging Page 451 Libraries By default the ticks are placed at 5cm distance but you can change this by setting tickstep to a different value tickstep 1cm ticklength 2mm drawticks fullsquare xscaled 4cm yscaled 3cm tickstep
166. eference Page 124 Bounding boxes draw bbox currentpicture withpen pencircle scaled 5mm withcolor 625red addto finalpicture also currentpicture shifted n 3cm 0 currentpicture nullpicture n nti enddef fill shape draw shape filldraw shape drawfill shape currentpicture finalpicture Here we introduce a macro definition shape In metarost the start of a macro definition is indicated with the keyword def Thereafter you can insert other variables and commands even other macro definitions The keyword enddef signals the end of the macro definition The result is shown in figure 2 1 watch the bounding boxes Close reading of the macro will reveal that the i11 draw filldraw and drawfill macros are applied to the first unitsquare path in the macro Figure 2 1 A fill draw filldraw and drawfill applied to the same square Page 125 Bounding boxes In this macro bbox calls a macro that returns the enlarged bounding box of a path By setting bboxmargin we can influence how much the bounding box is enlarged Since this is an existing variable we don t have to allocate it like we do with numeric n Unless you take special precautions variables are global by nature and persistent outside macros picture finalpicture finalpicture nullpicture Just as numeric allocates an integer variable the picture primitive allocates a picture data structure We explicitly have to set this picture to nothing u
167. eight 4 A few applications Page 534 Simple Logos We want sharp corners which can be achieved by setting 1inejoin to mitered linejoin mitered pickup pencircle scaled line The colors are rather primary blue and yellow At the time of writing this manual Dutch trains are still painted yellow so we will use that shade as background color color nsblue nsblue saa OOD mes color nsyellow nsyellow 1 1 0 We will now describe the main curves Although these expressions are not that advanced they demonstrate that we can express relationships instead of using assignments zi 0 height 2 z2 width 2 height 4 y1 z3 width 2theight 4 y4 z4 width 0 path p p z1 z2 z3 z4 Although it is accepted to consider z to be a variable it is in fact a vardef macro that expands into a pair x y This means that the previous definitions internally become x1 y1 0 height 2 x2 y2 width 2 height 4 y1 x3 y3 width 2theight 4 y4 x4 y4 width 0 A few applications Simple Logos These 8 relations can be solved by metarosr since all dependencies are known x1 0 yl height 2 x2 width 2 height 4 y2 yl x3 width 2theight 4 y3 y4 x4 width y4 0 Since we express the variables x and y in terms of relations we cannot reuse them because that would mean that inconsistent relations occur So the following lines will lead to an error message
168. elcome to MetaPost Page 35 Constructing paths GAD lbs 074a Bic EWES subpath 2 45 3 85 Often we want to take a slice starting at a specific point This is provided by cutafter and its companion cutbefore Watch out this time we use a non cyclic path WAV 5 oh 5 WADo ova Welcome to MetaPost Page 36 Constructing paths TCAs ols HAR oFAS cutar Cer F422 z0 z1 z22 z3 cutbefore z1 content index reference Page 37 Constructing paths Here is asomewhat silly way of accomplishing the same thing but it is a nice introduction to METAPOST s point operation In order to use this command effectively you need to know how many points make up the path zO z1 z2 z3 cutbefore point 2 of z0 z1 z2 z3 As with subpath you can use fractions to specify the time on the path although the resulting point is not necessarily positioned linearly along the curve Welcome to MetaPost Page 38 Constructing paths z0 Zl Z22 z3 c tbefore point 2 5 of 20 z1 22 23 If you really want to know the details of where fraction points are positioned you should read the METAFONT book and study the source of METAFONT and METAPOST where you will find the complicated formulas that are used to calculate smooth curves NAO oil o GELS Welcome to MetaPost Page 39 Constructing paths Like any closed path this path has points where the tangent is horizontal or vertical Early in this chapter w
169. ell as the distance from the parent point determine the curve Just in case you are interested in how such graphical simulations can be organized we show simplified versions of the macros used here In the previous examples we minimized the complexity of the code by using buffers but describing this mechanism is out of the scope of this section A few more details Page 140 Curve construction first order curve second order curve third order curve A few more details left side curves right side curves Page 141 Curve construction first order points third order points left side points right side points content index reference Page 142 Curve construction first iteration second iteration third iteration fourth iteration fifth iteration sixths iteration A few more details Page 143 Curve construction We need to loop over all segments of a curve where for each segment the left and right side sub curves are handled recursively upto the requested depth denoted as n For this we define the following macros vardef dodrawmidpoints expr a b c d n BENE Gy ty By lly ay J 8 weule Gy ky Sy ty ay J s osien a g Siloe Slle clll It Oled 3 al 8 Sibel g 5 s Slim al 8 draw j if n gt 1i dodrawmidpoints a e h j n 1 dodrawmidpoints j
170. ellipsed frame using the following definition startuniqueMPgraphic lions a path p p fullsquare xyscaled overlaywidth overlayheight superellipsed 85 pickup pencircle scaled ipt fill p withcolor 850white draw p withcolor 625yellow stopuniqueMPgraphic defineoverlay lions uniqueMPgraphic lions a As you may know x s ambassador lis a flion while METAFON nT fis fis represented by f a lioness if is a CD if they have fa elationship but if o and TA a baby fis b born may it it C IX enjoy METAFUN Enhancing the layout startuseMPgraphic lions b path p p fullsquare xyscaled overlaywidth overlayheight randomized 5pt pickup pencircle scaled ipt fill p withcolor 850white draw p withcolor 625yellow stopuseMPgraphic defineoverlay lions uniqueMPgraphic lions b startuniqueMPgraphic lions c path p p fullsquare xyscaled overlaywidth overlayheight squeezed 2pt pickup pencircle scaled ipt fill p withcolor 850white draw p withcolor 625yellow stopuniqueMPgraphic defineoverlay lions uniqueMPgraphic lions c content index reference 4 6 Jad rou Fa aman Xl a Fae z H H Jelationship A bof hnd H X q A K F j al z These paragraphs were typeset with the following settings setupalign broad right veryraggedright
171. en for different purposes text menus buttons etc For this reason CONTEXT provides not only left and right margins but also additional left and right edge areas and top and bottom margins These areas are shown in the figure on the next page When defining this graphic all areas have related dimensions Here it makes sense to let meTaPosT calculate these dimensions as much as possible First we define the five by five matrix of areas We pass the width and height of the main text area Because they are stored in Tpx dimension registers we have to prefix them by the pickup pencircle scaled 2pt numeric wl h xf yl u u 5cm numeric width width the textwidth numeric height height the textheight We now specify the lower left corners using instead of the which means that metarost will calculate w 3 and h 3 for us wit 2u w 2 3u w 4 3u w 5 h i tu h 2 tu h 4 tu h 5 w 1 w 2 w 3 w 4 w 5 4u width h 1 h 2 h 3 h 4 h 5 4u height x i 1u yi 1u Page backgrounds Page 279 The basic layout edge margin text margin edge ag S __ S _J _YYYY Sae pea Ss es eee ee Se SSS SSS S x 2 x 1 wl1 5u yl2 y 1 h 1 5u content index reference gt gt Page 280 The basic layout eS xe lt gt well gt ou 2 ILE yA P in Bu 5 LEI x 3 w 3 5u y 4 y 3 h 3 5u
172. en pencircle scaled 5pt withcolor 625yellow currentpicture currentpicture scaled 4 enddef stopbuffer The graphic itself is defined as follows Watch how we use the default buffer to keep the definitions readable startbuffer startcombination 5 1 A few applications Page 528 Growing graphics processMPbuffer a b c h d e f g 1 step 1 processMPbuffer a b c h d e f g 2 step 2 processMPbuffer a b c h d e f g 3 step 3 processMPbuffer a b c h d e f g 4 step 4 processMPbuffer a b c h d e f g 5 step 5 stopcombination stopbuffer placefigure here fig 1 till 5 The five graphics each with the same bounding box getbuffer step 1 step 2 step 3 step 4 step 5 Figure 13 5 The five graphics each with the same bounding box As the original purpose of these graphics was not to show them side by side but to present them as field stack in a document to be viewed at the computer screen For this purpose we have to define the graphics as symbols A few applications Page 529 Growing graphics definesymbol step 1 processMPbuffer a b c d e f g 1 definesymbol step 2 processMPbuffer a b c d e f g 2 definesymbol step 3 processMPbuffer a b c d e f g 3 definesymbol step 4 processMPbuffer a b c d e f g 4 definesymbol step 5 processMPbuffer a b c d e f g 5 A field stack is a sequence of overlayed graphics We will a
173. enpart i bluepart i endfor PP enddef A few more details We probably need to handle a few more border cases but for general purposes this macro works as expected From the previous examples it may be clear that each picture has some associated data stored with it From the bounded boolean test we can conclude that the bounding box is part of this data Internally metaPost keeps track of two bounding boxes the natural one and the forced one The forced one is actually a component of the picture which applies to all previously added graphics You can calculate the bounding box from the llcorner and urcorner or if you like ulcorner and 1rcorner and the METAFUN command boundingbox does so The four corners that make up the bounding box are either the natural ones or the ones forced by setbounds You can force MeTArOST to report the natural ones by setting truecorners to 1 The next example demonstrates this feature pickup pencircle scaled 2mm path p q draw fullcircle scaled 4cm slanted 5 withcolor 625white setbounds currentpicture to boundingbox currentpicture enlarged 5mm interim truecorners 0 p boundingbox currentpicture interim truecorners 1 q boundingbox currentpicture pickup pencircle scaled imm draw p withcolor 625red draw q withcolor 625yellow We use interim because truecorners is an internal METAPOST variable A few more details Page 192 Pitfalls Pitfalls When writ
174. ept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting an arly well executed butin my opinion the article is charmingly written as well However despit pny overall enthusiasm for Knuth s idea and article there are some points in it that I feel might aken wrongly by many readers and since they are points that touch close to my deepest interest artificial intelligence and esthetic theory I felt compelled to make some comments to clarify ain important issues raised by The Concept of a Meta Font fe thrive in information thick worlds because of our marvelous and everyday capacity to select t single out structure highlight group pair merge harmonize synthesize focus organize lense reduce boil down choose categorize catalog classify list abstract scan look into lealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend pect filter lump skip smooth chunk average approximate cluster aggregate outline sum arize itemize review dip into flip through browse glance into leaf through skim refine jumerate glean synopsize winnow the wheat from the chaff and separate the sheep from oats mald E Knuth us I came to the conclusion that the designer of a new system must not only be the implement d first large scale user the designer should also write the first us
175. er manual separation of any of these four components would have hurt THX significantly If I had articipated fully in all these activities literally hundreds of improvements would never have b ade because I would never have thought of them or perceived why they were important jut a system cannot be successful if itis too strongly influenced by a single person Once the init ign is complete and fairly robust the real test begins as people with many different viewpoint dertake their own experiments louglas R Hostadter Id Knuth has spent the past several years working on a system allowing him to control pects of the design of his forthcoming books from the typesetting and layout down to the vei shapes of the letters Seldom has an author had anything remotely like this power to control appearance of his or her work Knuth s TIX typesetting system has become well known an wvailable in many countries around the world By contrast his METAFONT system for designing of typefaces has not become as well known or available his article The Concept of a Meta Font Knuth sets forth for the first time the underlying hhilosophy of METAFONT as well as some of its products Not only is the concept exiting an early well executed but in my opinion the article is charmingly written as well However despit xy overall enthusiasm for Knuth s idea and article there are some points in it that I feel might wrongly by many readers and since they are
176. er sheet arrangements of 2 upto 32 or more pages per sheet are made The process of arranging pages in such a way that these sheets can be folded and combined into books is called page imposition CONTEXT Page backgrounds supports a wide range of page imposition schemes More information on this can be found in the CONTEXT manuals The fact that the sheet on which a page is printed is larger than the page itself opens the possibility to use the full page for content In that case especially when you use background graphics you need to make sure that indeed the page is covered completely Where in desk top printing you can get away with imperfection simply because the printing engines have their limitations in professional output you need to be more considerate Slightly enlarging a graphic so that it exceeds the natural page limits is called bleeding Because quite often layout elements have a rectangular nature METAFUN provides a couple of operations that can save you some work in defining bleeding boxes content index reference This graphic is generated as follows path p q def ShowPath fill p withcolor transparent 1 5 625yellow fill q withcolor transparent 1 5 625yellow currentpicture currentpicture shifted 25mm 0 enddef q fullsquare xyscaled 2cm 3cm ShowPath p leftenlarged 2mm ShowPath p topenlarged 2mm ShowPath p rightenlarged 2mm ShowPath p bottomenlarged 2mm ShowPath
177. ere we are on the path that is involved For this we use points on the path Unfortunately we can only use these points when we know where they are located In this section we will combine some techniques discussed in previous sections We will define a few macros manipulate some paths and draw curves and points 6 This circle is drawn by scaling the predefined path fullcircle This path is constructed using 8 points As you can see these points are not distributed equally along the path In the following graphic the second and content index reference Page 109 Cutting and pasting third point of the curve are colored red and point 2 5 is colored yellow Point 0 is marked in black This point is positioned halfway between point 2 and 3 It is clear that unless you know exactly how the path is constructed other methods should be available A specific point on a path is accessed by point of butthenext example demonstrates two more alternatives path p p fullcircle scaled 3cm xscaled 2 pickup pencircle scaled 5mm draw p withcolor 625white draw point 3 of p withcolor 625red draw point 6 along p withcolor 625yellow draw point 3cm on B So in addition to on to specify a point by number in meTAaPosT terminology called time we have along to specify a point as fraction of the path and on to specify the position in a dimension Welcome to MetaPost The on and along operators are macros and can be defi
178. es although gray colors are re duced to the more efficient POSTSCRIPT setgray operators in the output the macro MPcolor takes care of the translation from CMYK to RGB as well as gray to RGB However there is a fundamental difference between a yellow as defined in CONTEXT using CMYK and a RGB yellow in METAPOST definecolor cmyyellow y 1 definecolor rgbyellow r 1 g 1 definecolor cmydarkyellow y 625 definecolor rgbdarkyellow r 625 g 625 Figure 3 3 demonstrates what happens when we multiply colors by a factor Since we are not dealing with real CMYK colors multiplication gives different results for CMYK colors passed as MPcolor content index reference yellow 1 1 0 Gore on0 MPcolor rgbyellow MPcolor rgbdarkyellow 5 MPcolor rgbyellow MPcolor cmyyellow MPcolor cmydarkyellow 5 MPcolor cmyyellow Figure 3 3 All kinds of yellow So 625red is the same as r 5 but 625yellow is not the same as y 5 but matches r 5 g 5 Figure 3 4 shows the pure and half reds In order to prevent problems we advise you to stick to RGB color specifications when possible That way you not only prevent conversion problems but also get more predictable results on printing and viewing devices However reality demands that sometimes CMYK colors are used so how can we deal with that In the METAFUN macro collection there is a macro cmyk that takes four arguments representing the cyan ma genta yellow
179. es In that case we give them names This time we should say typebuffer mfun to typeset the code verbatim Instead of Tex code we can put METAPOST definitions in buffers Buffers can be used to stepwise build graphics By putting code in multiple buffers you can selectively process this code startbuffer red drawoptions withcolor 625red stopbuffer content index reference Page 214 Communicating color startbuffer yellow drawoptions withcolor 625yellow stopbuffer We can now include the same graphic in two colors by simply using different buffers This time we use the special command processMPbuf fer since getbuffer will typeset the code fragment which is not what we want startlinecorrection blank processMPbuf fer red graphic stoplinecorrection The line correction macros take care of proper spacing around the graphic The blank directive tells CONTEXT to add more space before and after the graphic startlinecorrection blank processMPbuf fer yellow graphic stoplinecorrection Which mechanism you use multiple buffers or re usable graphics depends on your preferences Buffers are slower but don t take memory while re usable graphics are stored in memory which means that they are accessed faster Communicating color Now that color has moved to the desktop even simple documents have become more colorful so we need a way to consistently apply color to text as well as graphics
180. es that this looks better indeed Also as TeX does the typesetting we get the current text font instead of the label font and the content will be properly typeset for instance kerning will be applied when applicable Spending some time on such details pays back in better graphics bottom Now what happens when we want to place labels in other positions In the worst case given that we place the labels manually we end up in vague arguments in favour for one or the other placement A few applications Page 480 Free labels upper right tight Although any automatic mechanism will be sub optimal we can give it a try to write a macro that deals with arbitrary locations This macro will accept three arguments and return a picture thefreelabel some string or picture a position the origin Our testcase is just a simple for loop that places a series of labels The freedotlabel macro is derived from thefreelabel pickup pencircle scaled imm path p p fullcircle scaled 3cm draw p withcolor 625yellow for 1 0 step 5 until 7 5 freedotlabel text point i of p center p endfor As a first step we will simply place the labels without any correction We also visualize the bounding box A few applications Page 481 Free labels vardef thefreelabel expr str loc ori save s picture s s thelabel str loc draw boundingbox s withpen penci
181. et 3pt TeX TeX TeX TeX TeX TeX TeX TeX framed backgroundoffset 3pt Tex stopcombination tt tt tt tt tt tt tt tt tt of fset none offset overlay offset Opt offset 1pt offset 2pt offset 4pt offset 3pt frameoffset 3pt backgroundoffset 3pt As the first row in figure 4 1 demonstrates instead of a value one can pass a keyword The overlay keyword implies that there is no offset at all and that the lines cover the content With none the frame is drawn tight around the content When the offset is set to Opt or more the text is automatically set to at least the height of a line You can turn this feature of by saying strut off More details can be found in the CONTEXT manual content index reference Page 229 Overlays ee E B SJ mee offset none offset overlay offset Opt ae Se offset 1pt offset 2pt offset 4pt T e ee offset 3pt frameoffset 3pt backgroundoffset 3pt Figure 4 1 The three offsets In figure 4 2 we have set offset to 3pt frameoffset to 6pt and backgroundoffset to 9pt Both the frame and background offset are sort of imaginary since they don t contribute to the size of the box ruledhbox framed offset 3pt frameoffset 6pt backgroundoffset 9pt background screen backgroundscreen 85 Welcome in the hall of frame Welcome in the hall of
182. et in the graphic The arguments passed to build_parshape are path an offset an additional horizontal and vertical displacement the baseline distance the height and depth of the line and the height of the first line topskip in TeX terminology The height and depth of a line are often called strut height and depth with a strut being an invisible character with maximum dimensions content index reference Page 436 Libraries startuseMPgraphic test 1 path p p fullcircle scaled 6cm build_parshape p 6pt 0 0 baselinedistance strutheight strutdepth strutheight draw p withpen pencircle scaled ipt stopuseMPgraphic The second shape is a diamond This is a rather useless shape unless the text suits the small lines at the top and bottom startuseMPgraphic test 2 path p p fullsquare rotated 45 scaled 5cm build_parshape p 6pt 0 0 baselinedistance strutheight strutdepth strutheight draw p withpen pencircle scaled ipt stopuseMPgraphic The third and fourth shape demonstrate that providing a suitable offset is not always trivial startuseMPgraphic test 3 numeric w h w h 6cm path p p 5w h 0 h 0 0 w 0 amp Typesetting in METAPOST Page 437 Libraries HO oo GUAD 2 Gila amp Gin eyele 5 build_parshape p 6pt 0 0 baselinedistance strutheight strutdepth strutheight draw p withpen pencircle scaled ipt stopuseMPgraphic Contrary to
183. etafun macro top center fullcircle metapost macro bot center fullcircle metapost macro lft pair lft center fullcircle metapost macro rt pair rt center fullcircle metapost macro oint numeric of path point 2 of fullcircle metapost primitive content index reference Page 630 Points oint numeric on path point 5 on fullcircle metafun macro oint numeric along path point 1cm along fullcircle metafun macro recontrol numeric of path precontrol 2 of fullcircle metapost primitive content index reference Page 631 Points ostcontrol numeric of path postcontrol 2 of fullcircle metapost primitive directionpoint pair of path directionpoint 2 3 of fullcircle metapost primitive numeric pair pair SOO ist metapost concept Reference ath intersectionpoint path Attributes withcolor rgbcolor withrebcolor rgbcolor mEn A Reference fullcircle intersectionpoint fulldiamond metapost macro withcolor 625 0 0 metapost primitive withrgbcolor 625 0 0 metapost primitive withcmykcolor cmykcolor witheray numeric withcolor cmyk c m y k a NA Reference Page 633 Attributes withcmykcolor 625 0 0 0 metapost primitive withgray 625 metapost primitive withcolor cmyk 0 625 625 0 metafun macro Page 634 Attributes withcolor transparent num num color withcolor transparent 1 625 red metafun macro wit
184. etarost syntax as well as most of the macros and variables defined in the plain metarost format that belongs to the core of the system They also include some of the more fundamental METAFUN commands atom variable argument number or fraction internal variable expression begingroup statement list expression endgroup nullary op btex typesetting command etex pseudo function METAPOST syntax Page 561 Syntax diagrams primary atom numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression numeric expression of operator expression of primary of operator expression along primary of operator expression on primary unary op primary str suffix z suffix numeric atom expression expression scalar multiplication op primary secondary primary secondary primary binop primary secondary transformer tertiary secondary tertiary secondary binop secondary METAPOST syntax subexpression tertiary path expression path join path knot expression subexpression expression tertiary binop tertiary path subexpression direction specifier path subexpression path join cycle path knot tertiary path join
185. example also demonstrated the use of MeTarost for rotating the picture The MPf igure macro encapsulates the code in a shortcut You can achieve special effects by using the layers behind floating bodies and alike but always keep in mind that the readability of the text should not be violated too much startbuffer setlayer BackLayer position yes voffset 1 5cm width 3cm height 2cm MPfigure somecow pdf scaled 5 slanted 5 Figure 5 2 stopbuffer placefigure right ruledhbox getbuffer In these examples we added a ruledhbox around the pseudo graphics so that you can see what the size is of those graphics We have already seen a lot of parameters that can be used to control the content of a layer There are a few more General housekeeping takes place with state start enable the layer stop disable the layer position no use absolute positions yes use relative positions overlay idem but ignore the size direction normal put new data on top reverse put new data below old data Positional graphics Sometimes all data needs to be offset in a similar way You can use both offset parameters for that hoffset an additional horizontal displacement voffset an additional vertical displacement You can position data anywhere in the layer When positioning is turned on the current position will get a placeholder You can change the dimensions of that placeholder when position is set to overlay zero dimensio
186. extpage overlaybutton nextpage setupbackgrounds text text background nextpage dorecurse 20 input tufte par stoptext Note that you can move forward from page to page in the resulting PDF file by clicking on each page with the mouse Now compile this file without setting the background state to repeat and note the difference as you click pages with the mouse Setting the state was not needed when we used the page background setupbackgrounds page background nextpage The dorecurse macro is handy for testing since it saves us typing One can nest this macro as in dorecurse 20 dorecurse 10 Hello World par The current step is available in recurselevel and the depth nesting level in recursedepth Crossing borders In many cases the previously mentioned background areas will suffice but in the case of more complicated backgrounds you may wish to use Metarost to draw graphics that combine or span these areas At runtime CONTEXT saves information on the layout that can be picked up by metarost The framework for a page graphic is Page backgrounds Page 290 Crossing borders StartPage all kind of commands StopPage Between the StartPage and StopPage command you have access to a wide range of variables page PaperHeight PaperWidth PrintPaperHeight PrintPaperWidth PageOffset PageDepth margins TopSpace BackSpace text MakeupHeight MakeupWidth vertical TopHeight TopDistance HeaderHeight Heade
187. ey get with the purchase of a PC or software There is not so much basic in struction as of now as there in the old days showing the differences between good and bad typographic design Many people are just fascinated by their PC s tricks and think that a widely praised program called up on the screen will make everything automatic from now on Hermann Zapf content index reference Page 369 Outline fonts graphictext left sqrt 1itx over sqrt 2 x 2 right scaled 4 dashed evenly withdrawcolor 625red withfillcolor 850white withpen pencircle scaled 1 5pt In this example we also use a dashed line Instead of normal colors we could have used shades or transparent colors Instead of supplying the text directly you can use the indirect method This permits you to process rather complex data without messing up your METAPOST code Special effects Page 370 Outline fonts setMPtext some math 7 usemodule mathm1 xmlprocessdata main lt math xmlns http www w3c org mathml version 2 0 gt lt apply gt lt log gt lt logbase gt lt cn gt 2 lt cn gt lt logbase gt lt apply gt lt plus gt lt ci gt x lt ci gt lt cn gt 1 lt cn gt lt apply gt lt apply gt lt math gt ie Here we feed some MATHML into TEX which in turn shows up as a MEeTAPOST graphic graphictext MPstring some math scaled 4 withd
188. f unitslant is therefore better def unitslant origin origin shifted 1 1 enddef draw unitslant xscaled 5cm yscaled icm withpen pencircle scaled 5mm withcolor 625red An even better alternative is path unitslant unitslant origin origin shifted 1 1 draw unitslant xscaled 5cm yscaled icm withpen pencircle scaled 5mm withcolor 625yellow A few more details Scaling and shifting Page 137 Curve construction Curve construction Chapter 3 of the METAFONT book explains the mathematics behind the construction of curves Both METAFONT and metarost implement B zier curves The fact that these curves are named after Pierre B zier obscures the fact that the math behind them originates with Sergei Bernshtein The points on the curve are determined by the following formula z t 1 tzi 3 1 t tz2 3 1 t t z3 Bz Here the parameter t runs from 0 1 As you can see we are dealing with four points In practice this means that when we construct a curve from multiple points we act on two points and the two control points in between So the segment that goes from z to z4 is calculated using these two points and the points that METAFONT METAPOST calls post control point and pre control point A few more details 25 The previous curve is constructed from the three points z1 z4 and z7 The curve is drawn in meTtAPosT by z1 z4 z7 and is made up out of two segments The firs
189. fault dash pattern set The macro drawoptions provides you a way to set the default attributes drawoptions dashed evenly withcolor red Welcome to MetaPost el Page 74 Text Text Since METAFONT is meant for designing fonts the only means for including text are those that permit you to add labels to positions for the sole purpose of documentation Because mMeTAPOST is derived from METAFONT it provides labels too but in order to let users add more sophisti cated text like a math formula to a graphic it also provides an interface to TEX Because we will spend a whole chapter on using text in METAPOST We limit the discussion here to a few funda mentals pair a a 3cm 3cm label top top a label bot bot a label 1ft 1ft a label rt rt a These four labels show up at the position stored in the pair variable a anchored in the way specified after the period top IEE TE bot The command dotlabe1 also typesets the point as rather visible dot pair a a 3cm 3cm dotlabel top top a dotlabel bot bot a dotlabel 1ft lft a dotlabel rt rt a content index reference Page 75 Text top lftert bot The command thelabel returns the typeset label as picture that you can manipulate or draw afterwards pair a a 3cm 3cm pickup pencircle scaled imm drawdot a withcolor 625yellow draw thelabel rt the right way a withcolor 625red You can of course ro
190. figure step 2 definesymbol step 3 externalfigure step 3 definesymbol step 4 externalfigure step 4 definesymbol step 5 externalfigure step 5 Which method is used depends on the way the graphics are used In this example we wanted to change the definition of _everything so here the third method was quite useful Simple Logos Many company logos earn their beauty from their simplicity One of the logos that most Dutch people have imprinted in their mind is that of the Dutch Railway Company NS An interesting feature of this logo is that although it is widely known drawing it on a piece of paper from mind is a task that many people fail A few applications Page 533 Simple Logos This logo makes a good candidate for demonstrating a few fine points of drawing graphics like using linear equations setting line drawing characteristics clipping and manipulating bounding boxes The implementation below is quite certainly not according to the official specifications but it can nevertheless serve as an example of defining such logos As always we need to determine the dimensions first Here both the height and line width depend on the width of the graphic Instead of calculating the blue shape such that it will be a filled outline we will draw the logo shape using line segments This is why we need the line parameter numeric width width 3cm numeric height height width 2 numeric line line h
191. fineoverlay button uniqueMPgraphic right or wrong setupbuttons background button frame off hbox button previous previouspage quad button next nextpage quad button index index quad button table of contents content content index reference The buttons will look like Compare these with Here the graphic was defined as startuniqueMPgraphic wrong or right pickup pencircle scaled 3pt path p p unitsquare xscaled OverlayWidth yscaled OverlayHeight fill p withcolor 8white draw p withcolor 625red stopuniqueMPgraphic The last class of embedded graphics are the runtime graphics When a company logo is defined in a separate file mylogos mp you can run this file by saying startMPrun input mylogos stopMPrun Embedded graphics Page 209 Integrated graphics The source for the logo is stored in a file named mylogos mp beginfig 21 draw fullsquare withcolor 625red draw fullsquare rotated 45 withcolor 625red picture cp cp currentpicture def copy addto currentpicture also cp enddef copy scaled 9 withcolor 625white copy scaled 7 withcolor 625yellow copy scaled 6 withcolor 625white copy scaled 4 withcolor 625red copy scaled 3 withcolor 625white fill fullcircle scaled 2 withcolor 625yellow currentpicture currentpicture scaled 50 endfig end In this example the result is available in the virtual file mprun 21 This fil
192. for the number one iil four MI seven two m five Wi eight three WI six Wt ill nine startitemize fuzzy pack 2 broad columns three item one item two item three item four item five item six item seven item eight item nine stopitemize A careful reader will have noticed that the previous definition of the fuzzy counter drawing is not suited to generate the graphics we started with useMPgraphic fuzzycount n 1001 content index reference Page 315 Random graphics This time we want to limit the width to the current hnsize We only need to add a few lines of code Watch how we don t recalculate the bounding box when more lines are used startuseMPgraphic fuzzycount begingroup save height vstep hsize span drift d cp height 3 4 the bodyfontsize currentfontscale span 1 3 height drift 1 10 height hsize the hsize vstep the lineheight xmax hsize div 5span pickup re ie scaled 1 12 height def d uniformdeviate drift enddef for i 1 upto MPvar n xpos i 1 mod 5 xmax span ypos i 1 div 5 xmax vstep draw if i mod 5 0 d 4 5span d d 0 5span height d else d d d height d fi shifted xpos ypostd drift endfor picture cp cp currentpicture if ypart ulcorner cp ypart llcorner cp lt vstep setbounds currentpicture to llcorner cp shifted 0 ypart llcorner cp Shapes symbols
193. frame Figure 4 2 The three offsets content index reference Page 230 Overlay variables Overlay variables The communication between Tex and embedded metarost graphics takes place by means of some macros overlay status macro meaning overlaywidth the width of the graphic as calculated from the actual width and background offset overlayheight the height of the graphic as calculated from the actual height depth and background offset overlaydepth the depth of the graphic if available overlaycolor the background color if given overlaylinecolor the color of the frame overlaylinewidth the width of the frame The dimensions of the overlay are determined by dimensions of the background which normally is the natural size of a framed When a background offset is specified it is added to overlayheight and overlaywidth Colors can be converted by MPcolor and in addition to the macros mentioned you can use all macros that expand into a dimension or dimen register prefixed by the Tpx primitive the this and other primitives are explained in The TEXbook by Donald Knuth Stacking overlays A background can be a gray scale screen a color color a previously defined overlay identifier or any combination of these The next assignments are therefore legal content index reference Page 231 Foregrounds framed background color backgroundcolor red framed background screen backgrounds
194. fullcircle setbounds currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm 1 length 1 stroked false clipped false bounded true 2 length 1 stroked true clipped false bounded false setbounds currentpicture to fullcircle clip currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm A few more details Page 188 Analyzing pictures 1 length 1 stroked false clipped true bounded false 2 length 1 stroked true clipped false bounded false setbounds currentpicture to fullcircle draw fullcircle withpen pencircle scaled 3mm clip currentpicture to fullcircle 1 length 0 stroked false clipped false bounded true 2 length 1 stroked true clipped false bounded false The description lines were generated by the following loop n 0 3 for i within currentpicture n n 1 label n amp decimal length amp decimal length stroked amp condition stroked i clipped amp condition clipped i bounded amp condition bounded i 0 n 5cm endfor If we have a textual picture we can also ask for the text and font Take the following picture picture p p MetaFun normalinfont rm lmr10 scaled 2 rotated 30 slanted 5 A few more details Page 189 Analyzing pictures p p shifted 0 ypart center p currentpicture p Here we can ask for label rt textpart
195. g paths we first draw a few strange paths The last of these three graphics demonstrates the use of soft join WAV A 5 VAD 77S V2 wil pe Dz Watch how softjoin removes a point in the process of smoothing a connection The smoothness is accom plished by adapting the control points of the neighbouring points in the appropriate way content index reference Page 33 Constructing paths z0 z1 softjoin z2 z3 Once a path is known you can cut off a slice of it We will demonstrate a few alternative ways of doing so but first we show one more time the path that we take as starting point NFA0 5 oF oR a oFABo CHELLIS This path is made up out of five points where the cycle duplicates the first point and connects the loose ends The first point has number zero We can use these points in the subpath command which takes two arguments specifying the range of points to cut of the path specified after the keyword of Welcome to MetaPost Page 34 Constructing paths subpath 2 4 of z0 z1 z2 z3 cycle The new sub path is a new path with its own points that start numbering at zero The next graphic shows both the original and the subpath from point 1 upto 3 CGA Falke VADs on o Celle subpath 1 3 In spite of what you may think a point is not fixed This is why in metarost a point along a path is officially called a time The next example demonstrates that we can specify any time on the path W
196. gh browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus Icame to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Me
197. gning families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and Clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into idealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chunk average approximate cluster aggregate outline sum marize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Th
198. graphic draw page content index reference Page 300 Crossing borders StopPage stopreusableMPgraphic The right page text looks similar startreusableMPgraphic right page StartPage path Main Main lrcorner Field QuterMargin Text llcorner Field Text Text ulcorner Field Text Text urcorner Field OuterMargin Text includeMPgraphic draw page StopPage stopreusableMPgraphic Watch how we used a reusable graphic first and a simple usable one next Actually the next graphic is not a stand alone graphic startuseMPgraphic draw page Main Main enlarged 6pt pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red stopuseMPgraphic Page backgrounds We have seen some predefined paths and locations Apart from the Page path they take two arguments that specify their position on the layout grid path Area an area similar to a CONTEXT one pair Location the position of this area path Field the area positioned at the right place path Page the page itself Some less used and more obscure variables are the following numeric Hstep the horizontal distance to the previous area numeric Vstep the vertical distance to the previous area numeric Hsize the width of an area numeric Vsize the height of an area The array variables are accessed by using constants horizontal vertical LeftEdge Top LeftEdgeSe
199. ground However the good news is that since in many cases we want a consistent layout we only have to do it once The next table has some hashed backgrounds More information about how to define tables can be found in the CONTEXT documentation and Up To Date documents content index reference Page 319 Shape libraries Table 7 2 A hashed table This table is defined as bTABLE frame off meta hash linecolor darkyellow offset 3ex bTR bTD background meta hash right right eTD bTD background meta hash left left eTD bTD background meta hash horizontal horizontal eTD bTD background meta hash vertical vertical eTD eTR eTABLE The graphics themselves are defined in a MeTAPOsT module In this particular example the macro some_hash is defined in the file mp back mp This macro takes six arguments some_hash width height linewidth linecolor angle gap Because we don t want to define a specific overlay for each color and linewidth we will use variables in the definition of the unique graphic startuniqueMPgraphic meta hash linewidth linecolor angle gap if unknown context_back input mp back fi Shapes symbols and buttons Page 320 Shape libraries some_hash overlaywidth overlayheight MPvar linewidth MPvar linecolor MPvar angle MPvar gap stopuniqueMPgraphic These variables are preset using setupMPvariables setupMPvariables meta
200. gs organized startbuffer circle startuseMPgraphic followtokens path RotPath RotPath reverse fullcircle rotatedaround origin 90 xscaled overlaywidth yscaled overlayheight drawoptions withcolor 625red stopuseMPgraphic followtokens content index reference Page 443 This is just a dummy text kerned by T kern 1667em lower 5ex hbox E kern 125emX and typeset in a circle using setMFPfont M setMFPfont E setMFPfont T setMFPfont A setMFPfont P setMFPfont O setMFPfont S setMFPfont T quad stopbuffer defineoverlay edge getbuffer circle The text and graphics come together in a framed text startbuffer quote framed offset 6pt background edge frame of f getshapetext stopbuffer placefigure One more time Hofstadter s quotation getbuffer quote Libraries Here also Iwill rewrite things a bit so that we can avoid startMPdrawing outside the macro and thereby avoid problems I can also add the maps cdrom cover as example Typesetting in METAPOST oe fo Thi s ts R 7 Q Donald Knuth has amp R spent the past several years G working on a system allowing him to 9 a control many aspects of the design of his a forthcoming books from the typesetting and gt layout down to the very shapes of the letters 3 Seldom has an author had anything remotely like g this power to control the final appearance of his or her work K
201. h the textheight stopMPcode However in CONTEXT MKIV this method is no longer recomended as all processing happens in the same run anyway startMPcode numeric w h w the textwidth h w 2 picture p p picture q btex colored r 375 g 375 Meta is a female lion etex xysized w h btex colored r 625 Meta is a female lion etex xysized w h He I path b b boundingbox p draw p for i 28w 90h 85w 90h w 05h jouL ibbeS Te j Te RS C p path s s fullsquare xscaled 05w yscaled 4h shifted i clip r tos drawr draws endfor setbounds currentpicture to b stopMPcode Figure 10 2 shows the previous sentence in a slightly different look You may consider coloring the dots to be an exercise in clipping content index reference Page 395 Environments Figure 10 2 An example of clipping An environment can be reset with resetMPenvironment or by passing reset as key to startMPenvironment startMPenvironment reset usetypescript postscript texnansi mkii content index reference setupbodyfont postscript stopMPenvironment So to summarize if you re using CONTEXT MKIV you might as well forgot what you just read 10 3 Labels In METAPOST you can use the label macro to position text at certain points label x origin The font and scale are determined by two variables defaultfont and defaultscale the
202. h p drawpoints p p p blownup 5cm drawpath p drawpoints p The shortened operation also scales the path but only makes it longer or shorter This macro only works on straight paths path p p 0 0 2cm 3cm drawpath p drawpoints p p p shortened icm drawpath p drawpoints p p p shortened 1cm drawpath p drawpoints p Welcome to MetaPost Page 99 Some extensions Here are a few more drawing helpers Even if you don t need them you might at some point take a look at their definitions to see what happens there First we give a square round corners with roundedsquare path p p roundedsquare 2cm 4cm 25cm drawpath p drawpoints p Next we draw a square like circle or circle like square using tensecircle Welcome to MetaPost Page 100 Some extensions path p p tensecircle 2cm 4cm 25cm drawpath p drawpoints p e Often I make such helpers in the process of writing larger drawing systems Take crossed path p p origin crossed 1cm drawpath p drawpoints p p origin crossed fullcircle scaled 2cm crossed 5cm shifted 3cm 0 drawpath p drawpoints p These examples demonstrate that a path is made up out of points something that you probably already knew by now The metarost operator of can be used to access a certain point at a curve Welcome to MetaPost Page 101 Some extensions path p p fullsquare xyscaled 3cm 2cm
203. hash gap 25 bodyfontsize angle 45 linewidth overlaylinewidth linecolor overlaylinecolor The last step in this process is to define the different alternatives as overlays def metahashoverlay 1 uniqueMPgraphic meta hash angle 1 def ineoverlay meta hash right metahashoverlay 45 def ineoverlay meta hash left metahashoverlay 45 def ineoverlay meta hash horizontal metahashoverlay 180 defineoverlay meta hash vertical metahashoverlay 90 As we can see in the definition of the table we can pass settings to the bTABLE command Actually we can pass such settings to each command that supports backgrounds or more precisely framed Table 7 3 is for instance defined as Shapes symbols and buttons bTABLE frame off meta hash linewidth 4pt align middle offset 2ex bTR bTD background meta hash left meta hash right meta hash linecolor darkyellow left par amp par right eTD bTD background meta hash horizontal meta hash vertical meta hash linecolor darkred horizontal par amp par vertical eTD eTR eTABLE The long names are somewhat cumbersome but in that way we can prevent name clashes Also since the METAPOST interface is english the variables are also english Table 7 3 A double hashed table content index reference Symbol collections Page 322 Symbol collections In CONTEXT a symbol can be defined without much coding
204. he same as those to framed getMPlayer test frame on offset 5pt useMPgraphic oeps Positional graphics Page 273 Complex text in graphics As you see you need a bit of a twisted mind to handle graphics this way but at least the functionality is there to create complex graphics in a declarative way Positional graphics Page 274 The basic layout Page backgrounds Especially in interactive documents adding backgrounds to the page and text areas not only enhances readability but also makes it more convenient to identify header footers and navigational areas In this chapter we will demonstrate that with METAPOST we can go beyond the Tex based features present in CONTEXT One section is dedicated to graphics and printing especially bleeding The basic layout In the CONTEXT manual you can find many details on the composition of the page When Tpx typesets text crossing the page boundary triggers TEX s output routine This routine is responsible for pasting the body text that goes onto a page in the correct area A simple representation of such a page is Page backgrounds The red areas are the header and footer while the yellow areas contains the text flow We can turn headers on and off and or hide them For this reason the header text and footer areas together make up the height of the text A close look at the left picture will reveal that the two arrows point to the center of the lines This is achieve
205. hey also have to deal with attributes like the pen and color they draw with Welcome to MetaPost Page 50 Drawing pictures You can use doublepath and contour directly but we will use draw and fi11 whenever possible Given a picture pic the following code is valid addto currentpicture also pic You can add pictures to existing picture variables where currentpicture is the picture that is flushed to the output file Watch the subtle difference between adding a doublepath contour or picture Here is another nice example of what happens when you fill a path that is partially reversed fill fullsquare rotated 45 scaled 2cm withcolor 625 red fill fullcircle scaled 2cm reverse fullcircle scaled Icm cycle withcolor 625 yellow The inner circle is indeed not filled Welcome to MetaPost Page 51 Variables Variables At this point you may have noted that Metarost is a programming language Contrary to some of today s languages MetarosT is a simple and clean language Actually it is a macro language Although MeTAPOsT and Tpx are a couple the languages differ in many aspects If you are using both you will sometimes wish that features present in one would be available in the other When using both languages in the end you will understand why the conceptual differences make sense Being written in PASCAL it will be no surprise that MetaPost has some PASCAL like features although some may also recognize features fr
206. hics defineoverlay FunnyFrame useMPgraphic FunnyFrame defineframedtext FunnyText frame off background FunnyFrame def StartFrame startFunnyText def StopFrame stopFunnyText def FrameTitle 1 setMPtext FunnyFrame hbox spread 1em hss strut 1 hss setMPtext FunnyFrame initialize the text variable There is a little bit of low level Tpx code involved like a horizontal box hbox that stretches one em space beyond its natural size spread 1em with a centered text two times hss Instead of applying this spread we could have enlarged the frame on both sides In the previous graphic we calculated the big rectangle taking the small one into account This was needed because we don t use a background fill The next definition does so there we can use a more straightforward approach by just drawing and filling the small rectangle on top of the big one startuseMPgraphic FunnyFrame grap y picture p numeric o path a b pair c p textext rt MPstring FunnyFrame Enhancing the layout unitsquare xyscaled OverlayWidth OverlayHeight BodyFontSize p p shifted 20 0verlayHeight ypart center p drawoptions withpen pencircle scaled ipt withcolor 625red b a randomized 0 2 fill b withcolor 85white draw b b boundingbox p randomized 0 8 fill b withcolor 85white draw b draw p withcolor black setbounds currentpicture to a stopuseMPgraphic There
207. his bonus explanation content index reference The centers of each square can also be calculated by metarost The next lines define that those points are positioned halfway the extremes zi z3 orsiz 1m2 mE 0 5 z31 z33 z4 On Silkz21uez2 Sila 0 5 z41 z43 Once we have defined the relations we can let meTarost solve the equations This is triggered when a variable is needed for instance when we draw the squares and their diagonals We connect the centers of the squares using a dashed line style Just to be complete we add a symbol that marks the right angle First we determine the common point of the two lines that lays at whatever point metarost finds suitable The definition of mark_rt_angle is copied from the meTarost manual and shows how compact a definition can be see page 22 for an introduction to zscaled startMPdefinitions solvers angle_radius 10pt def mark_rt_angle expr a b c draw 1 0 1 1 0 1 zscaled angle_radius unitvector a b shifted b enddef stopMPdefinitions So far most equations are rather simple and in order to solve them metarost did not have to work real hard The only boundary condition is that in order to find a solution MeTAaPosT must be able to solve all dependencies content index reference Page 83 Linear equations The actual value of the whatever variable is that it saves us from introducing a slew of variables that will never be used again We cou
208. hree drawing modes method result a punked curve drawn using a smooth curve drawn using a tight curve drawn using If method 2 or 3 do not give the desired outcome you can try a smaller step combined with method 1 draw function 1 log x x 1 10 1 xyscaled 10cm 2cm withpen pencircle scaled 5mm withcolor transparent 1 5 yellow draw content index reference _ Page 381 Drawing functions il 0x10 Figure 9 2 An example of a graphic with labels along the axes Functions function 2 5log x x 1 10 1 xyscaled 10cm 2cm withpen pencircle scaled 5mm withcolor transparent 1 5 blue The first argument to the function macro specifies the drawing method The last three arguments are the start value end value and step The second and third argument specify the function to be drawn In this case the pairs x x and 5log x x are calculated textextoffset ExHeight drawoptions withpen pencircle scaled 50pt draw hlingrid 10 10 1 10cm 10cm draw vlingrid 0 20 1 10cm 20cm shifted 0 10cm drawoptions draw function 2 x sind x 0 360 10 xyscaled 1cm 36 10cm withpen pencircle scaled 5mm withcolor transparent 1 5 blue draw function 2 x sin x pi 0 epsed 2 1 xyscaled 10cm 2 5cm withpen pencircle scaled 5mm withcolor transparent 1 5 yellow draw function 2 x cosd x 0 360 10 xyscaled 1cm 36 10cm content index reference w
209. hshade numeric metafun macro Shades need to be declared before they can be re used dashed withdots dashed withdots metapost primitive content index reference dashed evenl withpen pencircle transform Reference dashed evenly metapost primitive withpen pencircle scaled 2mm metapost macro withpen pensquare scaled 2mm metapost macro Page 636 Attributes withpen penrazor transform withpen penrazor scaled 2mm metapost macro withpen penspeck transform withpen penspeck metapost macro draw fullcircle metapost macro Reference fill fullcircle metapost macro filldraw fullcircle metapost macro drawfill fullcircle metapost macro content index reference drawdot drawdot origin metapost macro drawarrow drawarrow fullcircle metapost macro undraw fullcircle metapost macro unfill fullcircle metapost macro content index reference unfilldraw undrawdot Reference unfilldraw fullcircle metapost macro undrawfill fullcircle metapost macro undrawdot origin metapost macro Reference Page 640 Attributes origin 1 1 metapost macro linecap butt metapost variable Page 641 Attributes linecap rounded metapost variable linecap squared metapost variable Reference Reference Page 642 Attributes linejoin mitered metapost variable linejoin rounded metapost variable
210. ic This shape is not that beautiful but it has a few characteristics that will help us to identify bordercases startuseMPgraphic text draw drawarrow p withpen pencircle scaled 1pt withcolor red stopuseMPgraphic Now we use CONTEXT s includeMPgraphic command to build our graphic from the previously defined com ponents startuseMPgraphic text includeMPgraphic text path includeMPgraphic text draw stopuseMPgraphic When called with useMPgraphic text we get content index reference Page 418 Talking to Tix For the moment we start the path at x 0 y gt 0 but later using more complicated macros we will see that we can use arbitrary paths We are going to split the path in two and will use the points that make up the bounding box as calcutated by METAPOST The next graphic shows one of these points the lower left corner available as point llcorner p startuseMPgraphic text draw draw p withpen pencircle scaled 3pt withcolor red draw boundingbox p withpen pencircle scaled ipt draw llcorner p withpen pencircle scaled 5pt stopuseMPgraphic Typesetting in METAPOST Page 419 Talking to Tex The five points that MeTarosT can report for each path or picture are llcorner lrcorner urcorner ulcorner center lower left corner lower right corner upper right corner upper left corner intersection of the diagonals If we want to typeset text inside this circle we need to know where a line
211. ie Donald E Knuth Edward R Tufte Hermann Zapf A Simple Style Demo Hans Hagen August 2000 Figure 12 1 The lines used to calculate the button shapes Defining styles Page 461 Adaptive buttons startuseMPgraphic page includeMPgraphic rightsuperbutton StartPage path p q pickup pencircle scaled 3pt p Field Text Text enlarged 36pt superellipsed 90 fill Page withcolor MPcolor yellow fill p withcolor MPcolor white draw p withcolor MPcolor red p Field Text Text enlarged 48pt superellipsed 90 def right_menu_button expr nn rr pp xx yy ww hh dd if pp gt 0 and rr gt 0 q rightsuperbutton p xx yy RightEdgeWidth hh fill q withcolor MPcolor white draw q withcolor if rr 2 MPcolor gray else MPcolor red fi Seah lt p enddef MPmenubuttons right Defining styles StopPage stopuseMPgraphic The TeX macro MPmenubuttons expands into a list of in this case four calls to the mMeTAPOsT macro right_menu_button This list is generated by CONTEXT when it generates the menu Because the page back ground is applied last this list is available at that moment expr nn rr pp xx yy ww hh dd This rather long list of arguments represents the following variables number referred page current page x coordinate y coordinate width height and depth The last six variables originate from the positioning mechanism Because the variables are only ava
212. ight vfill but CloseDocument close stopinteractionmenu We have now arrived at the more interesting part of the style definition the graphic that goes in the page background Because this graphic will change we define a useable metaPosT graphic Page backgrounds are recalculated each page opposite to the other backgrounds that are calculated when a new background is defined or when repetitive calculation is turned on setupbackgrounds page background page def ineoverlay page useMPgraphic page setupMPvariables page alternative 3 We will implement three alternative backgrounds First we demonstrate the relatively simple super ellipsed one The main complication is that we want the button shapes to follow the right edge of the curve that surrounds the text We don t know in advance how many lines of text there will be in a button and we also don t know at what height it will end up Therefore we need to calculate each button shape independently and for that purpose we need to know its position see chapter 5 In figure 12 1 you can see what lines we need in order to be calculate the button shapes We separate the calculation of the button shape from the rest by embedding it in its own usable graphic con tainer The StartPage StopPage pair takes care of proper placement of the whole graphic content index reference Page 460 Adaptive buttons Douglas R Hofstadter n Frew Nh ee O Vea pt nc SSS v
213. ign is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font Figure 6 5 A random text area includeMP
214. igning layout down to the very shapes of families of typefaces has not the letters Seldom has an au become as well known thor had anything remotely or available like this power to con In his ar trol the final ticle Concept of a Meta Font Knuth points in it that I feel might sets forth for the first time the be taken wrongly by many underlying philosophy of readers and since they are METAFONT as well as some points that touch close to of its products Not only my deepest interests in is the concept exiting and artificial intelligence and clearly well executed but esthetic theory I felt com in my opinion the article is pelled to make some com charmingly written as well ments to clarify certain However despite my over important issues raised by all enthusiasm for Knuth s The Concept of a Meta idea and article there are some Font test 3 test 4 Figure 10 3 A continuous text typeset in a non standard shape spread over four areas content index reference Donald Knuth has spent the past several years working on a system al lowing him to control many as pects of the design of his forthcom ing books from the typesetting and layout down to the very shapes of the letters Seldom has an au thor had anything remotely like this power to con trol the final Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only
215. ilable after a second Tex pass we only draw a button shape when the test for the page numbers succeeds startuseMPgraphic rightsuperbutton vardef rightsuperbutton expr pat xpos ypos wid hei save p ptop pbot t b edge shift width height path p ptop pbot pair t b numeric edge shift width height edge xpos wid shift ypos hei p rightpath pat Defining styles exit ad lt d gt infinity shift edge shift infinity shift hei edge shift hei p intersectionpoint ptop p intersectionpoint pbot subpath 0 xpart p intersectiontimes ptop of p subpath xpart p intersectiontimes pbot length p of p Go t point 1 of ptop amp point 1 of ptop point 1 of pbot amp point 1 of pbot b cycle enddef stopuseMPgraphic The calculation of the button itself comes down to combining segments of the main shape and auxiliary lines The rightpath macro returns the right half of the path provided This half is shown as a non dashed line Topics are identified with Topic which is an instance of chapter headings The number is made invisible Since it still is a numbered section header CONTEXT will write the header to the table of contents definehead Topic chapter setuphead Topic number no We will use a bold font in the table of contents We also force a complete list content index reference Page 464 Adaptive buttons setuplist T
216. ile The format macros in there use TX to typeset the core components of a number and use the dimensions of those components to compose combinations of signs numbers and superscripts In METAFUN we have the module mp form mp which contains most of the code in format mp but in a form that is a bit more suited for fine tuning This permits us to use either the composition method or to fall back on the textext method that is part of METAFUN That way we can also handle fonts that have digits with different dimensions Another change concerns the pattern separator Instead of a we use you can choose to set another separator but for embedded definitions is definitely a bad choice because Tpx sees it as a comment and ignores everything following it drawoptions withpen pencircle scaled 1pt withcolor 625yellow draw hlingrid O 10 1 3cm 3cm draw vlingrid 0 10 3cm 3cm draw hlingrid 0 3cm 3cm shifted 3 5cm 0 draw vloggrid 0 3cm 3cm shifted 3 5cm 0 draw hloggrid 0 3cm 3cm shifted 7 0cm 0 draw vlingrid 0 3cm 3cm shifted 7 0cm 0 draw hloggrid 0 3cm 3cm shifted 10 5cm 0 draw vloggrid 0 1 3cm 3cm shifted 10 5cm 0 Functions Page 376 Grids drawoptions withpen pencircle scaled 1pt withcolor 625yellow draw hlingrid O 10 1 3cm 3cm slanted 5 draw vlingrid O 10 1 3cm 3cm slanted 5 LSAS SSAA ay Using macros like these often involves a bit of trial and error
217. in PDF In the following examples we will use the next three colors definecolor a darkyellow definecolor b s 8 definecolor c darkred A shade is a fill with a stepwise change in color In POSTSCRIPT level 2 the way this color changes can be circular linear or according to a user defined function Circular and linear shades look like this content index reference Whow this is I As you can see the shade lays behind the text as a background overlay These overlays are unique METAPOST graphics so they will adapt themselves to the dimensions of the foreground defineoverlay circular shade uniqueMPgraphic CircularShade defineoverlay linear shade uniqueMPgraphic LinearShade The two framed texts are defined as framed background circular shade frame off bf white Hi there I m Circular and framed background linear shade frame off bf white Whow this is Linear We still have to define the graphics Here we use a macro that takes four arguments a path a number identi fying the center of shading and the colors to start and end with content index reference startuniqueMPgraphic CircularShade path p p unitsquare xscaled overlaywidth yscaled overlayheight circular_shade p 0 MPcolor a MPcolor b stopuniqueMPgraphic startuniqueMPgraphic LinearShade path p p unitsquare xscaled overlaywidth yscaled overlayheight linear_shade p 0 MPcolor a MPc
218. includeMPgraphic text split includeMPgraphic text draw stopuseMPgraphic This graphic is typeset with useMPgraphic text Before we are going to use them we define some variables that specify the text We use a baseline distance of 8 points The part of the line above the baseline is 7 2 points while the maximum depth is 2 8 points These ratios are the ones we use in CONTEXT Because we don t want the text to touch the circle so we define an offset too also startuseMPgraphic text vars baselineskip 8pt strutheight 7 2 10 baselineskip strutdepth 2 8 10 baselineskip content index reference offset baselineskip 2 topskip strutheight stopuseMPgraphic We more of less achieve the offset by scaling the path In doing so we use the width and height which we call hsize and vsize thereby conforming to the TeX naming scheme First we calculate both dimensions from the bounding box of the path Next we down scale the path to com pensate for the offset When done we recalculate the dimensions startuseMPgraphic text move pair 16 5 pathir IL ie 8 hsize xpart lrcorner p xpart llcorner vsize ypart urcorner p ypart lrcorner p xscaled hsize 2offset hsize yscaled vsize 2offset vsize hsize xpart lrcorner q xpart llcorner vsize ypart urcorner q ypart lrcorner stopuseMPgraphic We adapt the text split code to use the reduced path instead of the original
219. ing macros you need to be careful in what operations apply to what object There is for instance a difference between the following code pickup pencircle scaled 2pt draw 0 0 0 1 1 1 scaled 1cm withcolor 625 red draw 0 0 0 1 1 1 scaled 2cm withcolor 625 yellow A few more details Page 193 Pitfalls The scaled operates on the previous expression which in the first case is the point 1 1 and in the second case the whole path pickup pencircle scaled 2pt draw 0 0 0 1 1 1 cycle scaled 1cm withcolor 625 red draw 0 0 0 1 1 1 cycle scaled 2cm withcolor 625 yellow Here the last element in the first case is not the cycle and the next alternative does not help us much in discover ing what is going on Well at least something is going on because the result seems to have some dimensions pickup pencircle scaled 2pt draw 1 1 cycle scaled 1cm withcolor 625 red draw 1 1 cycle scaled 1cm withcolor 625 yellow A few more details The next lines demonstrate that we re dealing with the dark sides of MeTAPosT and from that we may conclude that in case of doubt it s best to add parenthesis when such fuzzy situations threaten to occur pickup pencircle scaled 2pt draw 0 1 1 1 cycle scaled 1cm withcolor 625 red draw 0 1 1 1 cycle scaled 1cm withcolor 625 yellow There are more cases where the result may surprise you Take the following code drawa
220. ing option option list METAPOST syntax Page 576 Syntax diagrams Page 577 Syntax diagrams drawing option withcolor color expression withrgbcolor rgbcolor expression withemykcolor cmykcolor expression withoutcolor withprescript string expression withostscript string expression withpen pen expression dashed picture expression withshade numeric expression drawing command draw picture expression option list fill type path expression option list fill type fill unfill refill draw undraw redraw filldraw drawfill unfilldraw drawarrow drawdblarrow cutdraw newinternal command newinternal internal type symbolic token list newinternal symbolic token list METAPOST syntax Page 578 Syntax diagrams message command errhelp string expression errmessage string expression filenametemplate string expression message string expression mode command batchmode nonstopmode scrollmode errorstopmode special command fontmapfile fontmapline special tracing command gt tracingall loggingall tracingnone if test if boolean expression balanced tokens alternatives fi METAPOST syntax alternatives empty else balanced tokens elseif boolean expression balanced tokens alternatives loop loop header loop text endfo
221. input mp tool or input metafun By loading this file the resulting graphic will provide a high resolution bounding box which enables more accurate placement The file also sets the prologues 1 so that viewers like GHOSTVIEW can refresh the file when it is changed Next we will introduce some more mMeTAPOST commands From now on we will omit the encapsulating beginfig and endfig macros If you want to process these examples yourself you should add those com mands yourself or if you use CONTEXT you don t need them at all pickup pencircle scaled 5cm draw unitsquare xscaled 8cm yscaled 1cm withcolor 625white draw origin withcolor 625yellow pickup pencircle scaled ipt draw bbox currentpicture withcolor 625red In this example we see a mixture of so called primitives as well as macros A primitive is something hard coded a built in command while a macro is a collection of such primitives packaged in a way that they can be recalled easily Where scaledis a primitive and draw a macro unitsquare is a path variable an abbreviation for Une Squance m On O KPO KEO ROD aee content index reference Page 120 Bounding boxes The double dash is also a macro used to connect two points with a straight line segment However cycle is a primitive which connects the last point of the unitsquare to the first on unitsquare s path Path variables must first be declared as in path unitsquare A large coll
222. int has at most two control points As you can see in the following graphic the endpoints of a non closed curve have only one control point Welcome to MetaPost Page 15 Paths ha This time we used the path 1 5cm 1 5cm 2cm 0Ocm 1icm 1cm When you connect points by a smooth curve metarosT will calculate the control points itself unless you specify one or more of them Fst This path is specified as 1cm icm 1 5cm 1 5cm controls 3cm 2cm 2cm 0cm Welcome to MetaPost Page 16 Paths In this path the second and third point share a control point Watch how the curve is pulled in that direction It is possible to pull a bit less by choosing a different control point 1cem 1cm 1 5cm 1 5cm controls 2 75cm 1 25cm 2cm 0cm Now we get 4 We can also specify a different control point for each connecting segment Welcome to MetaPost Page 17 Transformations This path is defined as 1cm icm controls 5cm 2cm and 2 5cm 2cm 2cm 5cm Transformations We can store a path in a path variable Before we can use such a variable we have to allocate its memory slot with path path p p 1cm icm 1 5cm 2cm 2cm Ocm Although we can manipulate any path in the same way using a variable saves us the effort to key in a path more than once Welcome to MetaPost Page 18 Transformations In this graphic the path stored in p is drawn twice once in its displaced
223. irst version of this document was written the main references for using CONTEXT in combination with metarost were the following Otten A F amp Hagen J 1998 ConTEXt an Excursion Hasselt Pragma ADE Hagen J 1999 ConTEXt the Manual Hasselt Pragma ADE Hagen J 1999 Charts Uncovered mp flowcharts Hasselt Pragma ADE Hagen J 1997 Steps mp stepcharts and tables Hasselt Pragma ADE As we moved on more resources became available but in the perspective of moving from CONTEXT MKII to MKIV the following make most sense as they introduce the new concepts Hagen J 2006 ConTEXt MKII MKIV The history of LUATsX 2006 2009 Hasselt Pragma ADE Hagen J 2009 Hybrid Technology The history of LUATsxX 2009 Hasselt Pragma ADE There are more manuals You can use the showcase document on the website and wiki aka contextgarden to browse all the documentation The show pdf files demonstrate a bit of combined TeX meTArost trickery Quite some articles have been written in user group journals and a lot of styles that come with CONTEXT or are published by users demonstrate how metarost can be used content index reference Tools Convenient use of METAPOST became possible when PDFTEX came around Its machinery made it possible to process graphics at runtime and embed them by parsing the result Han Th Thanh amp Rahtz S P Q amp Hagen J 1998 The pdfTgX manual Brno Hasselt Oxford The LUATsX f
224. is not so much basic instruction as of now as there was in the old days showing the differences between good and bad typographic design Because we use a random graphic we cannot guarantee beforehand that the left and right edges of the small shape touch the horizontal lines in a nice way The next alternative displaces the small shape plus text so that its center lays on the line On the average this looks better startuseMPgraphic FunnyFrame picture p numeric o path a b pair c p textext rt MPstring FunnyFrame a unitsquare xyscaled OverlayWidth OverlayHeight o BodyFontSize Enhancing the layout Graphics and macros p p shifted 20 0verlayHeight ypart center p drawoptions withpen pencircle scaled 1pt withcolor 625red b a randomized 0 2 fill b withcolor 85white draw b Cee cent Chapa c b intersectionpoint c shifted 0 0 c shifted 0 0 p p shifted c center p b boundingbox p randomized 0 8 fill b withcolor 85white draw b draw p withcolor black setbounds currentpicture to a stopuseMPgraphic There is not so much basic instruction as of now as there was in the old days showing the differences between good and bad typographic design Yet another definition uses super ellipsed shapes instead of random ones We need a high degree of superness 95 in order to make sure that the curves don t touch the texts startuseMPgraphic FunnyFrame
225. ithpen pencircle scaled 5mm withcolor transparent 1 draw function 2 x cos x pi 0 epsed 2 gt 5 red 1 xyscaled 10cm 2 5cm withpen pencircle scaled 5mm withcolor transparent 1 5 green In this example we draw sinus and cosine functions using degrees and radians In the case of radians the end points are not calculated due to rounding errors In such case you can use the epsed value which gives slightly more playroom draw function 1 x sin 2x cals withpen pencircle scaled imm withcolor draw function 1 Sin 2x x 1 withpen pencircle scaled imm withcolor draw function 1 Sin 2x x x 1 withpen pencircle scaled imm withcolor vow He 10 01 scaled 1 5cm transparent 1 5 red 10 01 scaled 1 5cm transparent 1 5 green 10 01 scaled 1 5cm transparent 1 5 blue Of course you can do without a grid The next example demonstrates a nice application of transparencies WIN Functions M Page 384 Drawing functions Figure 9 3 By using transparent col ors we don t have to calculate and mark the common points they already stand out Functions Page 385 Drawing functions If we use the exclusion method for the transparencies combined with no transparency we get the following alterna
226. j 2 s 0 We now can say startcombination 3 4 MyTest 1 0 1 0 1 0 MyTest 0 8 1 0 0 0 MyTest 0 6 1 0 0 O MyTest 0 4 1 0 0 0 MyTest 0 2 1 0 0 0 MyTest 0 0 1 0 0 O MyTest 0 0 1 0 0 O MyTest 0 0 0 8 0 8 MyTest 0 0 0 6 0 6 MyTest 0 0 0 4 0 A MyTest 0 0 0 2 0 2 MyTest 0 0 0 0 0 0 stopcombination Watch how we pass the settings to the graphic definition using an extra argument We force using the solvers instance by prefixing the name Welcome to MetaPost Page 87 Linear equations It does not need that much imagination to see the four sided problem converge to a three sided one which itself converges to a two sided one In the two sided alternative it s not that hard to prove that the angle is indeed 90 degrees As soon as you can see a clear pattern in some code it s time to consider using loops In the previous code we used semi indexes like 12 in z12 In this case 12 does reflect something related to square 1 and 2 but in reality the 12 is just twelve This does not harm our expressions A different approach is to use a two dimensional array In doing so we can access the variables more easily using loops If we omit the labels and angle macro the previously defined macro can be reduced considerably def draw_problem expr n p q r s number and 4 positions begingroup save x y z 1 01
227. join rounded linejoin rounded linecap butt linecap rounded linecap squared A AN linejoin beveled linejoin beveled linejoin beveled linecap butt linecap rounded linecap squared Figure 1 1 The nine ways to end and join lines Welcome to MetaPost Page 71 Colors interim linejoin mitered for i 1 step 1 until 5 interim miterlimit i pt draw 0 0 5 1 1 0 shifted 1 5i 0 scaled 50pt withpen pencircle scaled 10pt withcolor 625red endfor The variables linejoin linecap and miterlimit are so called internal variables When we prefix their assign ments by interim the setting will be local within groups like beginfig endfig NANANA Colors So far we have seen some colors in graphics It must be said that MeTarost color model is not that advanced although playing with colors in the metaPosT way can be fun In later chapters we will discuss some extensions that provide shading Colors are defined as vectors with three components a red green and blue one Like pens colors have their with command withcolor 4 5 6 Welcome to MetaPost Page 72 Dashes You can define color variables like color darkred darkred 625 0 0 You can now use this color as withcolor darkred Given that red is already defined we also could have said withcolor 625red Because for mMeTAPOST colors are just vectors you can do things similar to points A color halfway red and green is therefore
228. kgrounds Page 297 Crossing borders startuseMPgraphic page StartPage def somewhere uniformdeviate 1cm uniformdeviate 1cm enddef path Main Main Field Text Text lrmoved somewhere Field Text Text llmoved somewhere Field Text Text ulmoved somewhere Field Text Text urmoved somewhere pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red StopPage stopuseMPgraphic Here we displace the corners randomly which leads to backgrounds like figure 6 5 The following definition would have worked as well startuseMPgraphic page StartPage path Main Main Field Text Text randomized 1cm pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white Page backgrounds draw Main withcolor 625red StopPage stopuseMPgraphic The previous graphics are defined as usable ones which means that they will be recalculated each page This is rather inefficient when the shapes don t change But using a reusable graphic instead would result in only one graphic for both pages Since the layout for the left and right page differs another method is needed Instead of putting the same graphic on the page layer we put two different ones on the left and right page layer defineoverlay left page useMPgraphic left page defineoverlay right page useMPgraphic right page setupbackgrounds leftpage b
229. l at arctime pos of RotPath ap point at of RotPath Typesetting in METAPOST Page 411 T X text ad direction at of RotPath draw pic i shifted wid 2 0 rotated angle ad shifted ap endfor stopMPdrawing MPdrawingdonetrue getMPdrawing resetMPdrawing egroup So how does this compare to earlier results The original full text as typeset by TFX looks like We now follow some arbitrary path In the examples the text is typeset along the path with followtokens We now follow some arbitrary path We now follow some arbitrary path Since we did not set a path a dummy path is used We can provide a path by re defining the graphic followtokens startuseMPgraphic followtokens path RotPath RotPath fullcircle stopuseMPgraphic Typesetting in METAPOST Page 412 T X text og Fe Py Fs startuseMPgraphic followtokens path RotPath RotPath reverse fullcircle stopuseMPgraphic rary as Ae D sary o E 3 v Y lt Y S Oroz S rox S startuseMPgraphic followtokens path RotPath RotPath 3cm 1cm 0 1cm 3cm 1cm stopuseMPgraphic Typesetting in METAPOST startuseMPgraphic followtokens path RotPath RotPath 3cm 0 3cm 1cm stopuseMPgraphic startuseMPgraphic followtokens path RotPath RotPath 3cm 0 1cm 1icm 3cm 0 stopuseMPgraphic wn go ioW SOME arbitr 9 Paty 9 rey are
230. lace the tension in the previous example by tension i and 2i we get the following graphic If we swap both values tension 2i and i we get A few more details We mentioned control points We will now draw a few extreme tensions and show the control points as METAPOST calculates them sample zi tension 0 75 z2 z3 625red sample z1 tension 2 00 z2 z3 625yellow sample z1 z2 z3 625white First we will show the symmetrical tensions content index reference Page 156 Inflection tension and curl The asymetrical tensions are less prominent We use the following values sample zi tension 75 and 10 oo Z2 55 Z3 625red 2 sample zi tension 10 and al co A aa 43 CAVOLO gt sample zi z2 z3 625white A few more details What happens when you use the meTarost maximum value of infinity instead of 10 Playing with this kind of graphic can be fun especially when we apply a few tricks def sample expr p c draw p withpen pencircle scaled 2 5mm withcolor white draw p withpen pencircle scaled 2 0mm withcolor c enddef 1cm z1 0 0 z2 2u 4u z3 4u 0 for i 0 step 05 until 1 sample zi tension 75 i z2 z3 i 625red 625yellow endfor A few more details Page 158 Inflection tension and curl Here we change the color along with the tension This clearly demonstrates that we re dealing with a non linear
231. lant hor_bar shifted 0 euro_v_delta right_slant hor_bar shifted 0 euro_v_delta euro_width 2 for i euro_circle euro_topbar euro_botbar draw i withpen pencircle scaled 0 endfor for i euro_circle euro_topbar euro_botbar fill i withpen pencircle scaled O endfor if trace_euro drawpoints euro_circle withcolor red drawpoints euro_topbar withcolor green drawpoints euro_botbar withcolor blue fane A few applications Page 550 The euro symbol enddef end_of_euro We only set a parameter when it is not yet set This has the advantage that we don t have to set them when we change one This way of manipulating paths cutting and building does not always work well because of rounding errors but here it does work euro_radius 4cm trace_euro true draw euro_symbol For educational purposes we have added a bit of tracing When enabled the euro shows up as Of course it would be best to define the euro as one shape but we won t go though that process right now By packaging the combined paths in an image we can conveniently color the euro symbol draw euro_symbol withcolor 625red A few applications You may wonder why we both draw and fill the euro using a pen with zero width We ve done this in order to demonstrate the redraw and refill macros redraw currentpicture withpen pencircle scaled 4pt withcolor 625yellow refill currentpicture withcolor 625white set
232. ld write zO A z1 z3 B z2 z4 and get the same result but the whatever variable saves us the trouble of introducing intermediate variables for which we have no use once the calculation is finished The macro mark_rt_angle draws the angle symbol and later we will see how it is defined First we draw the labels Unfortunately we cannot package btex etex into a macro because it is processed in a rather special way Each btex etex occurance is filtered from the source and converted into a snippet of TEx code When passed through Tx each snippet becomes a page and an auxiliary program converts each page into a METAPOST picture definition which is loaded by metarosr The limitation lays in the fact that the filtering is done independent from the metarost run which means that loops and other code are not seen at all Later we will introduce the METAFUN way around this In order to get all the labels typeset we have to put a lot of code here The macro dotlabel draws a dot and places the typeset label startMPdefinitions solvers def draw_problem_labels pickup pencircle scaled 5pt dotlabel 11ft Z_ 11 z11 dotlabel ulft Z_ 12 dotlabel ulft Z_ 13 z13 dotlabel 11ft Z_ 14 dotlabel 1rt Z_ 21 z21 dotlabel 11ft Z_ 22 dotlabel urt Z_ 23 z23 dotlabel ulft Z_ 24 content index reference Linear equations dotlabel urt Z_ 31 z31 dotlabel ulft Z_ 32
233. le type 1 height 1 25ex color darkred startuniqueMPgraphic smile type height color numeric size size MPvarfheight drawoptions withcolor MPvar color pickup pencircle xscaled size 6 yscaled size 12 draw halfcircle rotated 90 scaled size pickup pencircle scaled size 4 if MPvar type 1 for i 1 1 draw origin shifted 0 ixsize 4 endfor elseif MPvar type 2 for i 1 1 draw origin shifted size 2 ixsize 4 endfor pickup pencircle scaled size 6 draw size 4 0 size 4 0 fin stopuniqueMPgraphic We can now change some characteristics of the smilies without the need to redefine the graphic setupMPvariables smile height 1ex color darkred Shapes symbols and buttons In order to keep the smilies unique there is some magic involved watch the second argument in the next line startuniqueMPgraphic smile type height color Because unique graphics often are used in backgrounds its uniqueness is determined by the overlay charac teristics In our case however the uniqueness is determined by the smilies type height and color By explicitly specifying these we make sure that they count in the creation of the uniqueness stamp nidaligned switchtobodyfont 60pt symbol smile Because we use the ex height the previous call works as expected Shape libraries Unfortunately it takes some effort to define graphics attach them to an overlay and invoke the back
234. led 100bp A few more details Page 130 Units You might be tempted to omit the unit but this can be confusing particularly if you also program ina language like METAFONT where the pt is the base unit This means that a circle scaled to 100 in MetArost is not the same as a circle scaled to 100 in METAFONT Consider the next definition pickup pencircle scaled 0 fill unitsquare xscaled 400pt yscaled 5cm withcolor 625red fill unitsquare xscaled 400bp yscaled 5cm withcolor 625yellow drawoptions withcolor white label rt 400 pt origin shifted 0 25cm label rt 400 bp origin shifted 0 25cm When processed the difference between a pt and bp shows rather well Watch how we use rt to move the label to the right you can compare this with TexX s macro rlap You might want to experiment with 1ft top bot ulft urt 11ft and 1rt The difference between both bars is exactly 1 5pt as calculated by Tx 400 bp Where Tpx is anchored in tradition and therefore more or less uses the pt as the default unit metaPosT much like POSTSCRIPT has its roots in the computer sciences There to simplify calculations an inch is divided in 72 big points and 72pt is sacrificed A few more details When you consider that POSTSCRIPT is a high end graphic programming language you may wonder why this sacrifice was made Although the difference between 1bp and 1pt is miniscule this difference is the sou
235. ling x the least integer greater than or equal to x floor x the greatest integer less than or equal to x round x round each component of x to the nearest integer Of course we have x mod y the remainder of x y x div y the integer part of x y abs x the absolute value of x sqrt x the square root of x x dotprod y the dot product of two vectors What would life be without a certain randomness and uncertainty normaldeviate a number with mean 0 and standard deviation 1 uniformdeviate x anumber between zero and x The following functions are actually macros decr x n decrement x by n incr x n increment x by n Functions max a b return the maximum value in the list min a b return the minimum value in the list The min and max funtions can be applied to numerics as well as strings The following functions are related to strings oct s string representation of an octal number hex s string representation of a hexadecimal number str S string representation for a suffix ASCII s ASCII value of the first character char x character of the given ASCII code decimal x decimal representation of a numeric With substring i j of s youcan filter the substring bounded by the given indices from the given string In METAFUN we provide a few more functions you can take a look in mp tool mp to see how they are defined You need to be aware of very subtle rounding errors Normally these only show up when yo
236. lor 625yellow The resulting graphic has the bounding box of the fill Note how the path because it is stroked with a 5cm pen extends beyond the border of the previous bounding box The way this image shows up depends on the viewer settings you use to render the graphic For example in GHOSTVIEW if you disable clipping to the bounding box only the positive quadrant of the graphic is shown A few more details From the previous examples you can conclude that the following alternative results in a proper bounding box pickup pencircle scaled 5cm path p p unitsquare xscaled 8cm yscaled icm fill p withcolor 625white draw p withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled ipt withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow The CONTEXT distribution comes with a set of METAPOST modules one of which contains the drawfill macro which provides the outer bounding box Next we demonstrate its use in another more complicated example picture finalpicture finalpicture nullpicture numeric n n 0 bboxmargin Opt pickup pencircle scaled 5cm def shape unitsquare scaled 2cm withcolor 625white 5 Starting from version 1 0 Metarost calculates the boundingbox differently and the distinction between drawfill and filldraw is gone We keep them around both for compatibility content index r
237. m withpen pencircle scaled 1mm withcolor 625red draw origin bbwidth currentpicture 0 withpen pencircle scaled imm withcolor 625yellow draw origin 0 bbheight currentpicture withpen pencircle scaled imm withcolor 625white Units Like TEX METAPOST supports multiple units of length In Tx these units are hard coded and handled by the parser where the internal unit of length is the scaled point sp something on the nanometer range Because MeTAPOST is focused on POSTSCRIPT output its internal unit is the big point bp All other units are derived from this unit and available as numeric instead of hard coded Normally you will use grouping to keep the interim local In METAFUN each figure restores this variable at the beginning A few more details 2 83464 pt 0 99626 dd 1 06601 bp cm 28 34645 pc 11 95517 cc IP IPAS p alia 2 Careful reading reveals that only the bp and in are fixed while the rest of the dimensions are scalar multiples of bp Since we are dealing with graphics the most commonly used dimensions are pt bp mm cm and in a A 4k d The text in the center of the leftmost graphic is typeset by meTaPosT as a label fill fullsquare scaled 72 27pt withcolor 625yellow fill fullcircle scaled 72 2 7pt withcolor white label 72 27pt center currentpicture In metarost the following lines are identical draw fullcircle scaled 100 draw fullcircle sca
238. mbedded graphics Page 226 Overlays Enhancing the layout One of the most powerful and flexible commands of CONTgXT is framed We can use the background features of this command to invoke and position graphics that adapt themselves to the current situation Once understood overlays will become a natural part of the CONTEXT users toolkit Overlays Many CONTEXT commands support overlays The term overlay is a bit confusing since such an overlay in most cases will lay under the text However because there can be many layers on top of each other the term suits its purpose When we want to put a meTAPOST graphic under some text we go through a three step process First we define the graphic itself startuniqueMPgraphic demo circle path p p fullcircle xscaled overlaywidth yscaled overlayheight fill p withcolor 85white draw p withpen pencircle scaled 2pt withcolor 625red stopuniqueMPgraphic content index reference Page 227 Overlays This graphic will adapt itself to the width and height of the overlay Both overlaywidth and overlayheight are macros that return a dimension followed by a space The next step is to register this graphic as an overlay defineoverlay demo circle uniqueMPgraphic demo circle We can now use this overlay in any command that provides the framed functionality Since this graphic is defined as unique CONTEXT will try to reuse already calculated and embedded graphics when possible
239. me boxes involved which is due to the conversion of METAPOST Output to PDF startlinecorrection blank the graphic stoplinecorrection The small bar is a kern and the small rectangles are penalties More details on this debugger can be found in the CONTEXT manuals and the documentation of the modules involved content index reference Page 455 Adaptive buttons Defining styles Since the integration of METAPOST into CONTEXT a complete new range of layout fetaures became available In this document we have introduced several ways to include graphics in your document definition In this chapter we go one step further and make dynamic graphics part of a document style Adaptive buttons So far we have seen a lot of graphic ingredients that you can use to make your documents more attractive In this chapter we will define a simple document style This style was written for the PDFTEX presentations at the TUG 2000 conference in Oxford UK This style exploits a few tricks like graphics calculated using positional information It also demonstrates how you can make menu buttons that dynamically adapt their shapes to the rest of the page layout Defining styles Page 456 Adaptive buttons Later we will see an instance with some more randomness in the graphics While writing this style the random alternative made me think of those organic buildings with non equal windows we have a few of those in The Netherlands so I
240. more more readable code Fool yourself When doing a literature search on the human perception of black white edges I ran into several articles with graphics that I remember having seen before in books on psychology physiology and or ergonomics One of the articles was by Edward H Adelson of MIT and we will use a few of his example graphics in our exploration to what extend metarost can be of help in those disciplines Since such graphics normally occur in typeset documents we will define them in the document source A few applications Page 511 Fool yourself Figure 13 2 White s illusion Unless you belong to the happy few whose visual capabilities are not distorted by neural optimizations in figure 13 2 the gray rectangles at the left look lighter than those on the right Alas you can fool yourself but MeTAPOST does not cheat This graphic referred to as White s illusion is defined as follows startbuffer interim linecap butt numeric u u 1cm pickup pencircle scaled 5u for i 1u step u until 5u draw 0 i 5u i endfor for i 2u step u until 4u draw Cl n 3 withcolor 5white draw 3u i 4u i shifted 0 5u withcolor 5white A few applications endfor stopbuffer Watch how we include the code directly We have packaged this graphic in a buffer which we include as a floating figure placefigure here fig tricked 1 White s illusion processMPbuffer
241. ncluding metarost graphics The circles are defined as follows startMPpositiongraphic mypos circle initialize_box MPpos MPvar self path p p llxy lrxy urxy ulxy cycle pickup pencircle scaled ipt fill p withcolor 800white draw p withcolor 625yellow anchor_box MPanchor MPvar self stopMPpositiongraphic Drawing the lines is handled in a similar fashion startMPpositiongraphic mypos line path pa pb pab numeric na nb initialize_box MPpos MPvar from Mie B wey joel ky rry wie wb gy CyElle 3 initialize_box MPpos MPvar to nb s nxy pb llxy lrxy urxy ulxy cycle if na nb pab center pa center pb pab pab cutbefore pab intersectionpoint pa pab pab cutafter pab intersectionpoint pb Positional graphics Page 261 Anchors and layers pickup pencircle scaled ipt draw pab withcolor 625yellow anchor_box MPanchor MPvar from fain stopMPpositiongraphic The command startMPpositiongraphic defines a graphic in this example we have called it mypos circle The METAPOST macro initialize_box returns the characteristics of the box as identified by MPpos After this call the corners are available in 1lxy lrxy urxy and ulxy The center is defined by cxy and the path stored in pxy When we are finished drawing the graphic we can anchor the result with anchor_box This macro automatically handles positioning on specific layers The po
242. nd command you can put whatever text you wish your comments your grocery list whatever Comments in METAPOST prefixed by a percent sign asin Let s draw a circle are ignored by the interpreter but useful reminders for the programmer If the file is saved as yourfile mp then the file is processed by metarost by issuing the following command mpost yourfile after which you will have a graphic called yourfile 7 which contains a series of POSTSCRIPT commands Because metarost does all the work this file is efficient and compact The number of distinct POSTSCRIPT operators used is limited which has the advantage that we can postprocess this file rather easily Alternatively METAPOST can generate SVG output It does when you say outputformat svg Here we will not go into details about this format Even POSTSCRIPT is not covered in detail as we use METAPOST mostly in embedded form We can view this file in a POSTSCRIPT viewer like GHOSTVIEW or convert the graphic to PDF using mptopdf and view the result in a suitable PDF viewer like ACROBAT Of course you can embed such a file in a CONTEXT document using a command like externalfigure yourfile 7 We will go in more detail about embedding graphics in chapter 3 A few more details If you have installed CONTEXT somewhere on your system there resides a file mp tool mp If you make a stand alone graphic it s best to put the following line at the top of your file
243. ned as primarydef len on pat arctime len of pat of pat enddef primarydef pct along pat arctime pct arclength pat of pat of pat enddef These macros introduce two new primitives arctime and arclength While arctime returns a number de noting the time of the point on the path arclength returns a dimension When mathematicians draw parametric curves they frequently need to indicate the direction of motion I often have need of a little macro that will put an arrow of requested length anchored at a point on the curve and bending with the curve in the direction of motion content index reference Page 111 Cutting and pasting When David Arnold asked me how this could be achieved the fact that a length was requested meant that the solution should be sought in using the primitives and macros we introduced a few paragraphs before Say that we want to call for such an arrow as follows path p p fullcircle scaled 3cm pair q q point 4 along p pickup pencircle scaled 2mm draw P withcolor 625white drawarrow somearrow p q 2cm withcolor 625red draw q withcolor 625yellow Because we want to follow the path we need to construct the arrow from this path Therefore we first reduce the path by cutting off the part before the given point Next we cut off the end of the resulting path so that we keep a slice that has the length that was asked for Since we can only cut at points we determin
244. ng The macro ysized is part of the macros that come with CONTEXT and scales a picture to a specific size Page backgrounds Page 283 Setting up backgrounds startuniqueMPgraphic concept draw btex colored s 8 bf CONCEPT etex rotated 60 currentpicture currentpicture ysized overlayheight 5cm stopuniqueMPgraphic defineoverlay concept uniqueMPgraphic concept You can now put this graphic in the page background by saying setupbackgrounds page background concept You may consider the next alternative a bit better but still it renders the text unreadable Like xysized the macro enlarged is not part of standard metarost but comes with CONTEXT startuniqueMPgraphic copyright picture p p btex colored s 8 COPYRIGHT etex rotated 90 setbounds p to boundingbox p enlarged ipt draw p currentpicture currentpicture xysized overlaywidth overlayheight stopuniqueMPgraphic defineoverlay copyright uniqueMPgraphic copyright Page backgrounds Page 284 Setting up backgrounds Again we put this graphic in the background By using a unique graphic we make sure that it s rendered only once and reused when possible setupbackgrounds text rightmargin background copyright In both cases we slightly scale down the graphic We do so because otherwise a small portion of the text if clipped off This is unrelated to Tpx or MeTAPOST but a characteristic of the font C
245. ng Metarost and running METAFUN We will use lots of color Don t worry if your red is not our red or your yellow does not match ours We ve made color definitions to match the overall design of this document but you should feel free to use any color of choice in the upcoming examples We assume that you are using CONTEXT MKIV otherwise you need to run texexec with the mptex flag Conventions By default CONTgXT has turned its color mechanism on If you don t want your graphics to have color you should say setupcolors state stop Conventions Page 9 Paths Welcome to MetaPost In this chapter we will introduce the most important METAPOST concepts as well as demonstrate some drawing primitives and operators This chapter does not replace the METAFONT book or Metapost manual both of which provide a lot of explanations examples and dirty tricks As its title says the METAFONT book by Donald E Knuth is about fonts Nevertheless buying a copy is worth the money because as a METAPOST user you can benefit from the excellent chapters about curves algebraic expressions and linear equations The following sections are incomplete in many aspects More details on how to define your own macros can be found in both the METAFONT book and metarost manual but you will probably only appreciate the nasty details if you have written a few simple figures yourself This chapter will give you a start A whole section i
246. ng box is defined by its lower left and upper right corners If you open the POSTSCRIPT file produced by MeTAPOST you may find lines like BoundingBox 46 46 46 46 or when supported HiResBoundingBox 45 35432 45 35432 45 35432 45 35432 The first two numbers define the lower left corner and the last two numbers the upper right corner From these values you can calculate the width and height of the graphic A graphic may extend beyond its bounding box It depends on the application that uses the graphic whether that part of the graphic is shown In Metarost you can ask for all four points of the bounding box of a path or picture as well as the center llcorner p lower left corner Ircorner p lower right corner Welcome to MetaPost Page 90 Clipping urcorner p upper right corner ulcorner p upper left corner center p the center point You can construct the bounding box of path p out of the four points mentioned llcorner p lrcorner p urcorner p ulcorner p cycle You can set the bounding box of a picture which can be handy if you want to build a picture in steps and show the intermediate results using the same dimensions as the final picture or when you want to show only a small piece fill fullcircle scaled 2cm withcolor 625yellow setbounds currentpicture to unitsquare scaled icm draw unitsquare scaled 1cm withcolor 625red Here we set the bounding box with the command setbounds which takes a
247. ng path may look closed but is in fact open content index reference Page 29 Constructing paths WAV Mlk a Ms oA A Only a closed path can be filled The closed alternative looks as follows We will see many examples of filled closed paths later on NAO o All 5 oA Ao oO CHES Welcome to MetaPost Page 30 Constructing paths Here the final will try to make a smooth connection but because we already are at the starting point this is not possible However the cycle command can automatically connect to the first point Watch the difference between the previous and the next path NA 5 oll 5 os AS CYCLE It is also possible to combine two paths into one that don t have common head and tails First we define an open path 70 22d 22 Welcome to MetaPost Page 31 Constructing paths The following path is a closed one and crosses the previously shown path TAQ P6830 oala CEGA Ypuildcyclezo Hil 2A 5 AO 23 mil yelle We would refer readers to the METAFONT book and the Metarost manual for an explanation of the intricacies of the buildcycle command It is an extremely complicated command and there is just not enough room here to do it justice We suffice with saying that the paths should cross at least once before the buildcycle command can craft a combined path from two given paths We encourage readers to experiment with this command In order to demonstrate another technique of joinin
248. ngle 1 0 cycle scaled 3cm shifted 3 5cm 0 withcolor 625yellow draw origin 1 1 1 0 cycle scaled 3cm shifted 7cm 0 withcolor 625white The dir command returns an unit vector which is why the first two shapes look different and are smaller than the third one We can compensate for that by an additional scaling pickup pencircle scaled 2mm draw origin dir 45 dir 0 cycle Welcome to MetaPost scaled sqrt 2 scaled 3cm withcolor 625red draw origin dir angle 1 1 dir angle 1 0 cycle scaled sqrt 2 scaled 3cm shifted 4 5cm 0 withcolor 625yellow draw origin 1 1 1 0 cycle scaled 3cm shifted 9cm 0 withcolor 625white Drawing pictures Once a path is defined either directly or as a variable you can turn it into a picture You can draw a path like we did in the previous examples or you can fill it but only if it is closed Welcome to MetaPost Page 43 Drawing pictures Drawing is done by applying the draw command to a path as in draw Ocm icm 2cm 2cm 4cm 0cm cycle The rightmost graphic was made with fill fill Ocm icm 2cm 2cm 4cm 0cm cycle If you try to duplicate this drawing you will notice that you will get black lines instead of red and a black fill instead of a gray one When drawing or filling a path you can give it a color use all kinds of pens and achieve special effects like dashes or arrows
249. nk average approximate cluster aggregate outline sum marize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus I came to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for desi
250. nline tracingrestores tracingspecs tracingstats tracingtitles truecorners warningcheck year symbolic token defined by newinternal pseudo function min expression list max expression list incr numeric variable decr numeric variable dashpattern on off list interpath numeric expression path expression path expression buildcycle path expression list thelabel label suffix expression pair expression thefreelabel expression pair expression pair expression anglebetween pathexpression pathexpression expression pointarrow path expression numeric or pair primary numeric expression numeric expression leftarrow pathexpression numeric or pair primary numeric expression centerarrow path expression numeric or pair primary numeric expression rightarrow pathexpression numeric or pair primary numeric expression paired numeric or pair tripled numeric or color remappedcolor color expression METAPOST syntax path expression list path expression path expression list path expression on off list gt on off list on off clause on off clause on off clause on numeric tertiary off numeric tertiary boolean expression expression cmykcolor expression expression color expression expression numeric atom
251. nly to force consistency startuniqueMPgraphic super ellipse path p p unitsquare xscaled overlaywidth yscaled overlayheight content index reference Page 233 Foregrounds superellipsed 85 pickup pencircle scaled overlaylinewidth fill p withcolor MPcolor overlaycolor draw p withcolor MPcolor overlaylinecolor stopuniqueMPgraphic defineoverlay super ellipse uniqueMPgraphic super ellipse This background demonstrates that a super ellipse is rather well suited as frame framed background super ellipse frame off width 3cm align middle framecolor darkyellow rulethickness 2pt backgroundcolor darkgray white This is a Super Ellipsed sentence Such a super ellipse looks quite nice and is a good candidate for backgrounds for which the superness should be at least 85 Thisisa Super Ellipsed sentence Enhancing the layout Typesetting graphics I have run into people who consider it kind of strange when you want to use TeX for non mathematical type setting If you agree with them you may skip this section with your eyes closed One of the CONTEXT presentation styles number 15 tagged as balls stepwise builds screens full of sentences quotes or concepts packages in balloons and typesets them as a paragraph We will demonstrate that TEx can typeset graphics using the following statement As you may know TgX s ambassador is a lion while MeTAFONT is represented
252. nough to these kind of graphics it looks like the lines are no longer horizontal This table is defined as follows Shapes symbols and buttons Page 312 Random graphics starttabulate 1 cl1 HL NC system NC NC users NC NR HL NC Atari NC 10 4 NC useMPgraphic fuzzycount n 11 NC NR NC MSDOS NC 49 1 NC useMPgraphic fuzzycount n 52 NC NR NC 05 2 NC 9 4 NC useMPgraphic fuzzycount n 10 NC NR NC MacOS NC 5 7 NC useMPgraphic fuzzycount n 6 NC NR NC UNIX NC 51 9 NC useMPgraphic fuzzycount n 55 NC NR NC WINDOWS NC 64 2 NC useMPgraphic fuzzycount n 68 NC NR HL stoptabulate You will notice that we pass a variable to the graphic using a second argument We can access this variable with MPvar The graphic is defined as usable graphic because we want to generate a unique random one each time startuseMPgraphic fuzzycount begingroup save height span drift d cp height 3 5 baselinedistance span 1 3 height drift 1 10 height pickup pencircle scaled 1 12 height def d uniformdeviate drift enddef for i 1 upto MPvar n Shapes symbols and buttons Page 313 Random graphics draw if i mod 5 0 d 4 5span d d 0 5span height d else d d d height d fi shifted span i d drift endfor picture cp cp currentpicture for readability setbounds currentpicture to llcorner cp shifted 0 ypart llcorner cp
253. ns The A few more details Page 181 Directions freedotlabel macro is part of METAFUN and takes three arguments a label string or alternatively a picture a point location and the center of gravity The label is positioned in the direction opposite to this center of gravity pair destination for whereto up down left right destination scantokens whereto 1cm freedotlabel whereto destination origin drawarrow origin destination withpen pencircle scaled 25mm withcolor 625 red endfor So in this code fragment we use the string as string and by means of scantokens as a point or vector HE down The previous definition is a stepping stone to the next one This time we don t use points but the dir command This command converts an angle into an unitvector pair destination for whereto 0 step 30 until 330 content index reference Page 182 Analyzing pictures destination dir whereto 1 5cm freedotlabel decimal whereto destination origin drawarrow origin destination withpen pencircle scaled 25mm withcolor 625 red endfor In metrrost the angles go counter clockwise which is not that illogical if you look at it from the point of view of vector algebra 120 A Analyzing pictures Unless you really want to know all details you can safely skip this section The metapost features discussed here are mainly of importance when you write advanced ma
254. ns are used x the horizontal displacement y the vertical displacement width the non natural width height the non natural height location 1 rtbc1t 1b rt rb The location directive determines what point of the data is used as reference point You can keep track of this point and the placement when you enable test mode This is how the rectangles in the previous examples where drawn option test show positioning information When you are enhancing the final version of a document you can explicitly specify on what page the data will go Use this option with care page the page where the data will go content index reference Because layers can migrate to other pages they may disappear due to the background not being recalculated In case of doubt you can force repetitive background calculation by setupbackgrounds state repeat Complex text in graphics If you like to embed mMetarosT snippets in CONTEXT you may want to combine text and graphics and let META Post provide the position and the dimensions of the text to be typeset outside by TX For most applications using the METAFUN textext macro works well enough but when the typeset text needs to communicate with the typesetting engine for instance because it contains hyperlinks or references you can use the following method define a layer define a reusable graphic put your text into the layer combine the graphic with the text You must be aware of the fact that
255. nterim linecap butt pickup pencircle scaled gap draw 0 0 O height withcolor white stopuseMPgraphic The third row graphics again extend the first graphic First we copy the picture constructed so far Watch the double assignment Next we clip the pictures in half and shift the right half down over the width of the circle startuseMPgraphic third includeMPgraphic first picture p q p q currentpicture clip p to unitsquare xscaled width yscaled height clip q to unitsquare xscaled width yscaled height currentpicture p addto currentpicture also q shifted 0 radius 2 stopuseMPgraphic Growing graphics Although metarost is not really suited as a simulation engine it is possible to build graphics that are built and displayed incrementally with a sequence of mouse clicks The following example is the result of an email discussion David Arnold and the author had while METAFUN evolved Instead of defining the graphics in a separate metaPost file we will incorporate them in the document source in which they are used We can use several methods content index reference Page 518 Growing graphics Define macros and figures in a separate file and include the graphics as external graphics Define everything in the document source as usable graphics and include the graphics using useMPgraphic Package the graphic components in buffers and paste those together as graphics that can be processed at
256. nuth s Tex typesetting system has be come well known and available in many countries im around the world By contrast his METAFONT sys e tem for designing families of typefaces has not become as well known or available aN 2 In his article The Concept of a Meta a Font Knuth sets forth for the _ g first time the underlyin a 7 na A pP u e Xe L Figure 10 5 One more time Hofstadter s quotation Typesetting in METAPOST Page 445 Libraries Debugging Those familiar with CONTEXT will know that it has quite some visual debugging features build in So what may you expect of the METAPOST macros that come with CONTEXT In this chapter we will introduce a few commands that show some insight in what MeTAPOST is doing to your paths Since the outcome of METAPOST code is in many respects more predictable than that of Tpx code we don t need that advanced visual debugging features Nevertheless we provide a few that are all based on visualizing paths This visualization is achieved by using dedicated drawing commands content index reference path p p fullcircle scaled 4cm drawpath p drawpoints p drawpointlabels p Since control points play an important role in defining the shape visualizing them may shed some insight in what metarost is doing path p p fullcircle xscaled 4cm yscaled 3cm drawpath p drawcontrollines p drawpoints p drawcontrolpoints p draw
257. oblem The problem scale width textwidth useMPgraphic solvers one i 0 6 j 1 0 s 1 We will use this example to introduce a few new concepts one being instances In a large document there can be many metarost graphics and they might fall in different categories In this manual we have graphics that are generated as part of the style as wel as examples that show what METAFUN can do As definitions and variables in metarost are global by default there is a possibility that we end up with clashes This can be avoided by grouping graphics in instances Here we create an instance for the example that we re about to show def ineMPinstance solvers format metafun extensions yes initializations yes Welcome to MetaPost Page 78 Linear equations Welcome to Metal ost Page 79 Linear equations We can now limit the scope of definitions to this specific instance Let s start with the macro that takes care of drawing the solution to our problem The macro accepts four pairs of coordinates that determine the central quadrilateral All of them are expressions startMPdefinitions solvers def draw_problem expr p q r s show_labels begingroup save x y a b c d e f g h alll A2 jo 3 wel wil Zsil ral vailil 8 yi2 yall e 222 21 x32 oesyil Bae ye y3 e gl ay Gali wil 3 AIBS Gale y2 z13 x12 b y12 a z14 x11 b ylita wal Geil yal 3 2 G22 y2
258. ocess it with the METAPOST program or MPTOPDF Depending on what features you use the succes of a run depends on the proper set up of the programs that take care of running Tpx for btex You can embed the graphic in a startMPpage construct and process it with CONTEXT MKIV which is the future anyway In that case you have the full METAFUN functionality available If for some reason you still want to use MKII you need to use TeXEXEC as before processing the file it will do a couple of checks on the file It will also make sure that the temporary files mpt for textext s and mpo for outline fonts are taken care of too You can integrate the graphic in the document flow using buffers metaPosT code sections or reusable graphic containers In that case the graphics are processed runtime or between runs This happens auto matically Unless you want to write low level CONTgXT code yourself there is no real reason to look into the modules that deal with metarost support The traditional partly generic code is collected in METAFUN macros Page 559 Killing time supp mps tex low level inclusion macros and housekeeping supp mpe tex experimental extensions like specials supp pdf tex METAPOST to PDF conversion Especially the last two can be used in other macro packages However in CONTEXT we have regrouped the code plus more in other files meta tex definition and managing mlib tex processing and conversion The la
259. of visual debugging macros content index reference Page 483 Free labels e 2 6 As you can see point 1 is the corner point that suits best for alignment when a label is put at point 1 of the circle We will now rewrite thefreelabel in such a way that the appropriate point of the associated freesquare is found vardef thefreelabel expr str loc ori SWE Sy iy Ely IL uCS S joeNeln jo joule IL s thelabel str loc p fullcircle scaled 2 length loc ori shifted ori q freesquare xyscaled urcorner s llcorner s l point xpart p intersectiontimes ori loc of q draw q shifted loc withpen pencircle scaled 5pt draw 1 shifted loc withcolor 625yellow draw loc withcolor 625red s enddef A few applications Page 484 Free labels The macro xyscaled is part of METAFUN and scales in two directions at once The metarost primitive intersectiontimes returns a pair of time values of the point where two paths intersect The first part of the pair concerns the first path We are now a small step from the exact placement If we change the last line of the macro into s shifted 1 we get the displacement we want Although the final look and feel is also determined by the text itself the average result is quite acceptable A few applications Because we also want to pass pictures and add a bit of offset too the final implementation is slightly more complicated The picture is h
260. ollow up provided a more tight integration and runtime is now virtually zero The metarost 2 project is done alongside LUATEX development LuaTEX development team 2006 LuaTEX Reference www luatex org As we aim at upward compatibility as much as possible the older manuals still apply In MKIV much of the action is hidden for the user and installation is no issue Therefore no additional manuals need to be consulted Hagen J 1999 TeXexec explained Hasselt NL Pragma ADE Hagen J 1999 MakeMPY Hasselt NL Pragma ADE Hagen J 2000 Making Stand Alone MetaPost graphics Amsterdam NL NTG Maps Distributions Information about installing Tex can be found on the websites of user groups A convenient way to start with CONTEXT is to use the installer from contextgarden net The T X Live distribition as well as the MikT X win dows distribution come with CONTEXT content index reference Index a anchoring 254 257 angles 41 487 arguments 61 attributes 71 634 axis 374 b backgrounds 282 289 bleeding 304 boundingbox 120 buffers 211 c clipping 88 342 color 71 214 497 manipulating 355 common definitions 220 conditions 53 curl 146 curves 137 cutting 108 Page 652 Distributions d dashes 72 debugging 445 definitions 57 directions 179 drawing 42 e environments 393 equations 76 expressions 76 f functions 371 8 graphics 117 649 buffers 211 embedded 203 external 201 including
261. olor b stopuniqueMPgraphic The METAPOST macros circular_shade and linear_shade add information to the MeTarost output file which is interpreted by the converter built in CONTEXT Shading comes down to interpolation between two or more points or user supplied ranges A poor mans way of doing this is to build the graphics piecewise with slightly changing colors But instead of manually stepping through the color values we can use the more efficient and generalized POSTSCRIPT level 2 and PDF level 1 3 shading feature circular 0 circular 1 circular 2 circular 3 circular 4 Special effects Page 328 Shading linear 1 linear 2 linear 3 linear 4 linear 5 linear 6 linear 7 linear 8 Shading is not a MeTAPOsT feature which means that it has to be implemented using so called specials direc tives that end up in the output file Unfortunately these are not coupled to the specific path which means that we have to do a significant amount of internal bookkeeping Also in PDF we have to make sure that the graphics and their resources being the shading functions are packaged together Because of this implementation shading may behave somewhat unexpected at times A rather normal case is the next one where we place 5 shaded circles in a row path p p fullcircle scaled 1cm for i 0 step 2cm until 8cm circular_shade p shifted i 0 0 MPcolor a MPcolor b endfor Special effects Page 329 Shading
262. om ALGOL68 in it First there is the concept of variables and assignments There are several data types some of which we already have seen numeric real number in the range 4096 4096 boolean a variable that takes one of two states true or false pair point or vector in 2 dimensional space path a piecewise collection of curves and line segments picture collection of stroked or filled paths string sequence of characters like metapost color vector of three rgb or four cmyk numbers There are two additional types transform and pen but we will not discuss these in depth transform transformation vector with six elements pen pen specification Welcome to MetaPost Page 52 Variables You can achieve interesting effects by using pens with certain shapes For the moment you may consider a pen to be a path itself that is applied to the path that is drawn The numeric data type is used so often that it is the default type of any non declared variable This means that is the same as numeric n n 10 When writing collections of macros it makes sense to use the second method because you can never be sure ifn isn t already declared as a picture variable and assigning a numeric to a picture variable is not permitted Because we often deal with collections of objects such as a series of points all variables can be organized in arrays For instance numeric n n 3 10 n 5 13 An array i
263. ompare the following Pagella Latin Modern and Termes gi s the Pagella is the body font of this text showboxes hbox bgroup hbox definedfont file texgyrepagella regular at 6cm gi hbox def inedfont file 1mroman10 regular at 6cm git hbox definedfont file texgyretermes regular at 6cm gil egroup Page backgrounds Page 285 Setting up backgrounds Watch how the bounding boxes differ and sometimes cross the shape So in order not to loose part of a glyph when clipping you need to add a bit of space Figure 6 1 shows the two backgrounds in action If you really want to add such texts to a document in CONTEXT we don t have to use the page background but can use one of the layout areas instead like text text or text leftmargin setupframedtexts FunnyText backgroundcolor lightgray framecolor darkred rulethickness 2pt offset bodyfontsize before blank big medium Page backgrounds Setting up backgrounds Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into idealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chu
264. onstrating that stand alone graphics can be made Managing resources E A graphic consists of curves either or not filled with a given color A graphic can also include text which means that fonts are used Finally a graphic can have special effects like a shaded fill Colors fonts and special effects go under the name resources since they may demand special care or support from the viewing or printing device Special effects like shading are supported by dedicated metarost modules These are included in the CONTEXT distribution and will be discussed later in chapter 8 content index reference Since METAPOST supports color an embedded graphic can be rather colorful However when color support is disabled or set up to convert colors to gray scales CONTEXT will convert the colors in the graphics to gray scales You may wonder what the advantage is of weighted gray conversion Figure 3 9 shows the difference between natural colors weighted gray scales and straightforward non weighted gray scales full color weighted gray linear gray Figure 3 9 The advantage of weighted gray over linear gray When we convert color to gray we use the following formula This kind of conversion also takes place in black and white televisions G 30r 59g 11b Section 8 5 introduces the grayed operation that you can use to convert a colored picture into a gray one This macro uses the same conversion method as mentioned here E
265. ook into idealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chunk average approximate cluster aggregate outline sum marize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus I came to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her wo
266. opic criterium all style bold before after The TitlePage macro looks horrible because we want to keep the interface simple a list of small sentences separated by def TitlePage 1 startstandardmakeup switchtobodyfont big def vfill1 bfb let par bfd setupinterlinespace gray vskip 5cm 1 vskip 5cm is really needed stopstandardmakeup A presentation that uses this style may look like the one below You can choose among three alternatives useenvironment pre organic setupoutput pdftex setupMPvariables page alternative 1 starttext Defining styles TitlePage A Few Nice Quotes A Simple Style Demo Hans Hagen August 2000 Topic Douglas R Hofstadter input douglas page Topic Donald E Knuth input knuth page Topic Edward R Tufte input tufte page Topic Hermann Zapf input zapf page stoptext We will not implement the two other alternative shapes squeezed and randomized content index reference Page 466 Adaptive buttons CA Douglas R Hofstadter A Few Nice Quotes ip page 1 We combine all alternatives into one page graphic The alternative is chosen by setting the alternative vari able as we demonstrated in the example startuseMPgraphic page includeMPgraphic rightsuperbutton StartPage numeric alternative seed superness squeezeness randomness path p q transform t This is one of those cases where a transform va
267. orthcoming books from the typesetting and layout down to the ver even Page 294 Crossing borders ward R Tufte fe thrive in information thick worlds because of our marvelous and everyday capacity to it single out structure highlight group pair merge harmonize synthesize focus reduce boil down choose categorize catalog classify list abstract scan look into lealize isolate discriminate distinguish screen pigeonhole pick over sort integrate bl sct filter lump skip smooth chunk average approximate cluster aggregate outline sum s itemize review dip into flip through browse glance into leaf through skim merate glean synopsize winnow the wheat from the chaff and separate the sheep from oats ld E Knuth stale res EE a iCal E E aa first large scale user the designer should also write the first user manual separation of any of these four components would have hurt THX significantly If had articipated fully in all these activities literally hundreds of improvements would never have ide because I would never have thought of them or perceived why they were important jut a system cannot be successful if itis too strongly influenced by a single person Once the init is complete and fairly robust the real test begins as people with many different jertake their own experiments ugias R Hostadter Knuth has spent the past several years working on a system allowing him to control of the design of
268. ot only of height depth and width but also of the crossing of a page boundary and the height and depth of lines In some cases your graphics may have to respond to layout characteristics like differences between odd and even pages Given that unique identifiers are used for anchor points in CONTEXT you can have access to all the information needed ae Anchors and layers 7A 2 N In a previous section we saw that some Gord were Greed and connected by an Arrow As with most things in CONT XT marking these words is separated from d elaring what to do with those words This paragraph is keyed in as In a previous section we saw that some hpos X 1 words were hpos X 2 circled and connected by an hpos X 3 arrow As with most things in CONTEXT marking these words is separated from declaring what to do with those words This paragraph is keyed in as We see three position anchors each marked by an identifier X 1 X 2 and X 3 Each of these anchors can be associated with a series of graphic operations Here we defined setMPpositiongraphic X 1 mypos arrow to X 2 setMPpositiongraphic X 2 mypos arrow to X 3 content index reference Page 258 Anchors and layers These examples clearly demonstrate that we cannot control to what extent graphics will cover text and vice versa A solution to this problem is using position overlays We can define such an overlay as follows startpositionoverlay backgraphics
269. otatedText draw MPbetex RotatedText rotated MPvar rotation stopuseMPgraphic This works as expected RotatedText 165 Some Rotated Text 1x9 L Pa 2o ae 9S It is now a small step towards an encapsulating macro we assume that you are familiar with Tpx macro defin itions Enhancing the layout Page 241 Graphics and macros def RotatedText 1 2 setupMPvariables RotatedText 1 setMPtext RotatedText 2 useMPgraphic RotatedText setupMPvariables RotatedText rotation 90 startuseMPgraphic RotatedText draw MPbetex RotatedText rotated MPvar rotation stopuseMPgraphic Again we default to a 90 degrees rotation and pass both the settings and text in an indirect way This method permits you to build complicated graphics and still keep macros readable RotatedText rotation 240 Some Rotated Text You may wonder why we don t use the variable mechanism to pass the text The main reason is that the text mechanism offers a few more features one of which is that it passes the text straight on without the danger of content index reference Page 242 Graphics and macros unwanted expansion of embedded macros Using setMPtext also permits you to separate TEX and METAPOST code and reuse it multiple times imagine using the same graphic in a section head command There are three ways to access a text defined with setMPtext Imagine that we have the following definitions setMPtext 1
270. ow to integrate such gadgets yourself Interfacing to TEX In the early days of METAPOST support in CONTEXT Tobias Burnus asked me if it was possible to define English rules What exactly does an english rule look like Here is one As you can see such a rule has to adapt itself to the current text width normally hsize in Tex or on request localhsize in CONTEXT We need to set the height to a reasonable size related to the font size and we also need to take care of proper spacing Of course we want to run METAPOST as less times as possible so we need to use unique graphics Let s start with the graphic setupMPvariables EnglishRule height 1ex width localhsize color darkgray startuniqueMPgraphic EnglishRule height width color content index reference numeric height height MPvar height 0 x3 MPvar width x2 x4 5x3 yi y3 0 y2 y4 height 2 fill zi z2 z3 amp z3 z4 z1 amp cycle withcolor MPvar color stopuniqueMPgraphic As you can see we pass two arguments to the graphic definition The first argument is the name the second argument is a comma separated list of variables This list serves two purposes First this list is used to create a unique profile for the graphic This means that when we change the value of a variable a new graphic is generated that reflects the change A second purpose of the list is to convert Tpx data structures into METAPOST ones especially
271. ow we achieved the above result fill 0 0 0 h w h w 0 ww 0 w hh ww hh ww 0 cycle This feature depends on the POSTSCRIPT way of filling closed paths which comes down to filling either the left or the right hand side of a curve The following alternative works too fill 0 0 0 h w h w hh ww hh ww 0 w hh w 0 cycle The next alternative will fail This has to do with the change in direction at point 0 0 halfway through the path Sometimes changing direction can give curious but desirable effects but here it brings no good content index reference iP aLILIL 0 0 0 h w h w 0 0 0 Gww 0 ww hh w hh ww 0 cycle This path fails because of the way POSTSCRIPT implements its fill operator More details on how POSTSCRIPT defines fills can be found in the reference manuals Some of the operations we have seen are hard coded into metarost and are called primitives Others are defined as macros that is a sequence of MeTAaPOST commands Since they are used often you may expect draw and fill to be primitives but they are not They are macros defined in terms of primitives Given a path pat you can consider a draw to be defined in terms of addto currentpicture doublepath pat The fill command on the other hand is defined as addto currentpicture contour pat Both macros are actually a bit more complicated but this is mainly due to the fact that t
272. own here can span multiple pages In order to calculate the right backgrounds some additional information must be available like the top and bottom of the current text area In fact these are just normal points that can be saved while processing the split off page So apart from positioning anchors in the text we need anchors on crucial points of the layout This means that this kind of support cannot be fully integrated into the Tpx kernel unless we also add extensive support for layout definitions and that is probably not what we want As soon as something like x y shows up a logical question is where 0 0 is located Although this is a valid question the answer is less important than you may expect Even if we know that 0 0 is officially located in the bottom left corner of the page the simple fact that in CONTEXT we are dealing with a mixed page concept like paper size and print paper size or left and right pages forces us to think in relative positions instead of absolute ones Therefore graphics even those that involve multiple positions are anchored to a position on the layer on which they are located The MPanchor macro takes care of this content index reference Page 257 Anchors and layers Users who simply want to use these features may wonder why we go into so much detail The main reason is that in the end many users will want to go beyond the simple cases and when dealing with these issues you must be aware n
273. p butt for i 1 upto 5 draw 0 0 width 0 shifted 0 i 1 gap withpen pencircle scaled linewidth endfor A few applications Page 543 Music sheets for i llcorner currentpicture ulcorner currentpicture lrcorner currentpicture urcorner currentpicture draw i withpen pencircle scaled barwidth endfor enddef stopusableMPgraphic We can define the sidebars a bit more efficient using two predefined subpaths for i leftboundary currentpicture rightboundary currentpicture We define a macro MusicBar that takes four arguments The first two determine the dimensions the last two concern the line widths Now watch how we can use this macro includeMPgraphic bar draw MusicBar 200pt 6pt ipt 2pt draw MusicBar 300pt 6pt 1pt 2pt shifted 0 30pt 1 As you can see in this example the bar is a picture that can be transformed shifted in our case However a close look at the macro teaches us that it does a couple of draws too This is possible because we wrap the A few applications whole in an image using the image macro This macro temporary saves the current picture and at the end puts the old currentpicture under the new one We wrap the whole in a vardef This means that the image is returned as if it was a variable Actually the last thing in a vardef should be a proper return value in our case a picture This also means that we may not end the vardef with
274. pMPvariables meta button type 1 size 2 bodyfontsize fillcolor gray linecolor darkred These symbols are collected in table 7 4 and are called up with the CONTEXT commands like symbol menu left If needed we can collect these button symbols in a so called symbol set which permits us to instantly switch between sets with similar symbols Shapes symbols and buttons Page 324 Symbol collections lt i E E3 al ow A left right list index person stop info down up Table 7 4 A collection of button symbols Shapes symbols and buttons Page 325 Shading Special effects Sometimes we want to go beyond Metarost s native features Examples of such an extension are CMYK colors shading and transparency Although features like this should be used with care sometimes the documents look and feel can profit from it If you don t want the whole graphic but only a part of it clipping comes into play In addition to the standard clipping features we can use METAPOST to provide a decent clipping path In this chapter we will uncover the details We will also introduce ways to include externally defined graphics and outline fonts We will demonstrate that within reasonable bounds you can manipulate such graphics Shading In this section we introduce different kinds of shading Since meTarost does not support this feature directly we have to fall back on a few tricks For the moment shading is only supported
275. pace before than after the framed text We demonstrated that when defining graphics that are part of the layout you need to have access to informa tion known to the typesetting engine Take figure 4 4 The line height needs to match the font and the two thin horizontal lines should match the x height We also need to position the baseline being the lowest one of a pair of lines in such a way that it suits the proportions of the line as specified by the strut A strut is an imaginary large character with no width You should be aware of the fact that while Tex works its way top down in metarost the origin is in the lower left corner content index reference Page 252 Graphics and macros Figure 4 4 Penalty lines Enhancing the layout usetypescript serif chorus definef ont SomeHandwriting TeXGyreChorus MediumItalic at 12pt start SomeHandwriting setstrut startMPpage StartPage path p numeric 1 n 1 1 5LineHeight n 0 p origin shifted 1 0 origin shifted PaperWidth 1 0 for i PaperHeight 1 step 1 until 1 il Sin ap il 8 fill p shifted 0 i StrutHeight reverse p shifted
276. parator TopSeparator LeftMargin Header LeftMarginSeparator HeaderSeparator Text Text RightMarginSeparator FooterSeparator RightMargin Footer content index reference RightEdgeSeparator BottomSeparator RightEdge Bottom In addition to these there are Margin InnerMargin and OuterMargin which adapt themselves to the current odd or even page The same is true for Edge InnerEdge and OuterEdge although these will seldom be used since interactive documents are always single sided We started this chapter with spending a lot of code to simulate the page areas It will be clear now that in practice this is much easier using the mechanism described here In figure 6 6 we see all used areas Areas that are not used are not drawn which saves some testing This background was defined as startuseMPgraphic page StartPage for i Top Header Text Footer Bottom for j LeftEdge LeftMargin Text RightMargin RightEdge draw Field i j withpen pencircle scaled 2pt withcolor 625red endfor endfor StopPage stopuseMPgraphic We use two nested for loops to step over the areas A for loop witha step of 1 will fail because the indices are defined in a rather special way On the other hand the mechanism is rather tolerant in the sense that i j and j i are both accepted Page backgrounds Page 303 Crossing borders it single out structure highlight group pair merge harmonize synthesize focus organize
277. path zraphic extends beyond the bounding box but the bounding box determines the placement and therefore e spacing around the graphic We can get rid of the artwork outside the bounding box by clipping it fill fullcircle scaled 2cm withcolor 625yellow clip currentpicture to unitsquare scaled 1cm content index reference Page 91 Some extensions The resulting picture is just as large but shows less of the picture Some extensions We will now encounter a couple of transformations that can make your life easy when you use METAPOST for making graphics like the ones demonstrated in this document These transformations are not part of standard METAPOST but come with METAFUN A very handy extension is enlarged Although you can feed it with any path it will return a rectangle larger or smaller than the boundingbox of that path You can specify a pair or a numeric path p p fullsquare scaled 2cm drawpath p drawpoints p p p shifted 3cm 0 enlarged 5cm 25cm drawpath p drawpoints p Welcome to MetaPost There are a few more alternatives like bottomenlarged rightenlarged topenlarged and leftenlarged The cornered operator will replace sharp corners by rounded ones we could not use rounded because this is already in use pachipi ape A O O 2D 1 2 1 eyelle xysized 4cm 2cm drawpath p drawpoints p p p shifted 5cm 0 cornered 5cm drawpath p dra
278. path in expressions without the danger of handling r alone We can now implement left center and right arrows by providing this macro the right parameters The offset the fourth parameter is responsible for a backward displacement This may seem strange but negative values would be even more confusing def rightarrow expr p t 1 pointarrow p t 1 1 enddef def leftarrow expr p t l pointarrow p t 1 1 enddef def centerarrow expr p t 1 pointarrow p t 1l 0 enddef We can now apply this macro as follows path p p fullcircle scaled 3cm pickup pencircle scaled 2mm draw p withcolor 625white drawarrow leftarrow p A 2cm withcolor 625red drawarrow centerarrow p point 5 of p 2cm withcolor 625yellow draw point 4 along p withcolor 625yellow draw point 5 of p withcolor 625red content index reference Page 114 Cutting and pasting Watch how we can pass a point point 5 of p as well asa fraction 4 The following graphic demonstrates a few more alternatives The arrows are drawn using the previously defined macros Watch the positive and negative offsets in call to pointarrow drawarrow leftarrow p point 1 of p 2cm withcolor red drawarrow centerarrow p point 2 of p 2cm withcolor blue Welcome to MetaPost Page 115 Current picture drawarrow rightarrow p point 3 of p 2cm withcolor green drawarrow pointarrow p 60 4cm 5cm withcolor yellow drawarrow pointarrow p 75 3cm 5cm
279. pencircle scaled 1pt withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow In the third line we define a path variable We assign the current bounding box to this variable but first we set the offset to zero The last line demonstrates how to draw such a path Instead of setting the pen as we did in the first line we pass the dimensions directly Where draw draws a path the fill macro fills one In order to be filled a path should be closed which is accomplished by the cycle primitive as we saw in constructing the unitsquare path pickup pencircle scaled 5cm fill unitsquare xscaled 8cm yscaled icm withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled 1pt withcolor 625red draw origin withpen pencircle scaled 5pt withcolor 625yellow content index reference Page 122 Bounding boxes This example demonstrates that when we fill the path the resulting graphic is smaller Where draw follows the center of a path fi11 stays inside the path A third alternative is the illdraw macro From the previous examples we would expect a bounding box that matches the one of the drawn path pickup pencircle scaled 5cm filldraw unitsquare xscaled 8cm yscaled 1cm withcolor 625white path bb bboxmargin Opt bb bbox currentpicture draw bb withpen pencircle scaled ipt withcolor 625red draw origin withpen pencircle scaled 5pt withco
280. penpoint i 2 of p endfor cycle content index reference Page 176 Only this far withcolor 625red draw penpoint 0 2 of p for i 1 upto length p 1 penpoint i 2 of p endfor cycle withcolor 625yellow Another case when top and friends cannot be applied in a general way is the following Consider the three paths path p q r p fullcircle scaled 3cm q p shifted 7cm 0Ocm we 3 Comper pina EEimccie 6 We draw these paths with content index reference Page 177 Only this far draw p withpen pencircle scaled 10pt withcolor 625red draw q withpen pencircle scaled 10pt withcolor 625yellow draw r withpen pencircle scaled 20pt withcolor 625white The line is drawn from center to center and since the line has a non zero width and a round line cap it extends beyond this point If we want to line to stop at the circular paths we can cut off the pieces that extend beyond those paths pair pr qr pr p intersectionpoint r qr q intersectionpoint r r r cutbefore pr cutafter qr This time we get A few more details Page 178 Only this far Due to the thicker line width used when drawing the straight line part of that line is still visible inside the circles So we need to clip off a bit more r r cutbefore point 5pt on r r r cutafter point 5pt on r The point on operation is a METAFUN macro that takes a dimension A few mor
281. picture to boundingbox currentpicture enlarged 3pt stopuseMPgraphic In this graphic we have two text fragments the first one is a text the second one the name of the author We combine the quotation and author into this graphic using the following definitions setMPtext text vbox hsize 8 5cm input zapf setMPtext author hbox sl Hermann Zapf These definitions assume that the file zapf tex is present on the system which is the case when you have installed CONTEXT The graphic can now be typeset using the following call content index reference Page 367 Outline fonts placefigure A text does not need to be an outline in order to be typeset in an outline font useMPgraphic quotation The quality of the output depends on how the glyphs are constructed For instance in TeX math symbols are sometimes composed of glyph fragments and rules graphictext sqrt 1 x scaled 8 withdrawcolor 625red withpen pencircle scaled 1 5pt This is not really a problem because we can also fill the shapes It is the reason why the fill is applied after the draw and in such case the effective line width is half the size specified Special effects Coming back to the use of typefaces in elec tronic publishing many of the new typogra phers receive their knowledge and information about the rules of typography from books from computer magazines or the instruction manu als which th
282. pointlabels p The pre and post control points show up as small dots and are connected to their parent point with thin lines You can deduce the direction of a path from the way the points are numbered but using an arrow to indicate the direction is more clear content index reference Page 447 Libraries path p p fullcircle xscaled 4cm yscaled 3cm drawarrowpath p drawcontrollines p drawpoints p drawcontrolpoints p drawpointlabels p The drawarrowpath is responsible for the arrow Especially when you are in the process of defining macros that have to calculate intersections or take subpaths knowing the direction may be of help The next table summarizes the special drawing commands drawpath the path drawarrowpath the direction of the path drawcontrollines the lines to the control points drawpoints the points that make up the path drawcontrolpoints the control points of the points drawpointlabels the numbers of the points Debugging Page 448 Libraries You can set the characteristics of these like you set drawoptions The default settings are as follows drawpathoptions withpen pencircle scaled 5 withcolor 8white drawpointoptions withpen pencircle scaled 4 withcolor black drawcontroloptions withpen pencircle scaled 2 5 withcolor black drawlineoptions withpen pencircle scaled 1 withcolor 5white drawlabeloptions Two more options are draworiginoptions and drawboundoptions which are us
283. points that touch close to my deepest interes artificial intelligence and esthetic theory I felt compelled to make some comments to ertain important issues raised by The Concept of a Meta Font even odd Figure 6 6 A quick way to draw all used areas content index reference Page 304 Bleeding Bleeding If you want to share your document all over the world it makes sense to use a paper format like letter or A4 In that case the layout often matches the paper size The left picture demonstrates what happens when you have a printer that is capable of printing from edge to edge If you have such a printer you re lucky The middle picture demonstrates what happens if you have a properly set up printing program and or printer the page is scaled down so that the content fits into the non printable area of the printer One reason why printers don t print from edge to edge is that the engine is not that happy when toner or ink ends up next to the page The third picture shows what happens when a printer simply ignores content that runs over the non printable area In many cases it s best to make sure that the content leaves a margin of 5mm from the edges Books and magazines seldom use the popular desk top paper sizes Here the designer determined the paper size and layout more or less independent from the size of the sheet on which the result is printed Instead of one page p
284. pt the bounding box accordingly This means that a graphic has its natural dimensions unless of course we adapt the bounding box manually When you limit your graphic to a simple shape say a rectangle shifting it to some place can get obscured by this fact Therefore the following series of shapes appear to be the same A few more details Page 132 Scaling and shifting draw unitsquare xscaled 6cm yscaled 1 5cm withpen pencircle scaled 2mm withcolor 625red draw unitsquare shifted 5 5 xscaled 6cm yscaled 1 5cm withpen pencircle scaled 2mm withcolor 625red draw unitsquare shifted 5 5 xscaled 6cm yscaled 1 5cm withpen pencircle scaled 2mm withcolor 625red A few more details Page 133 Scaling and shifting draw unitsquare xscaled 6cm yscaled 1 5cm shifted 1cm 1cm withpen pencircle scaled 2mm withcolor 625red draw unitsquare xscaled 6cm yscaled 1 5cm shifted 1 5cm 1cm withpen pencircle scaled 2mm withcolor 625red However when we combine such graphics into one we will see in what respect the scaling and shifting actually takes place draw unitsquare xscaled 6cm yscaled 2cm withpen pencircle scaled 3 0mm withcolor 625yellow draw unitsquare shifted 5 5 xscaled 6cm yscaled 2cm A few more details withpen pencircle scaled 3 0mm withcolor 625red draw unitsquare xscaled 6cm yscaled 2cm shifted 1cm 1cm withpen pencircle scaled 3 0mm withcolor 625white draw unitsquare x
285. q cycle withcolor 625red The macro top uses the characteristics of the current pen to determine the displacement However for the more complicated pen shapes we need a different trick to get an inside path Let s start by defining an elliptical path pickup pencircle xscaled 3mm yscaled 5mm rotated 30 path p p fullcircle xscaled 6cm yscaled 3cm draw p withcolor 625white We draw this path using a non standard pen In the METAFONT manual you will find methods to draw shapes with similar pens where the pen is also turning as it does in real calligraphy Here we stick to a more simple one A few more details Page 173 Only this far We construct the inner path from the points that make up the curve Watch how we use a for loop to compose the new path When used this way no semi colon may be used to end the loop since it would isolate the color directive draw point 0 of p for i 1 upto length p point i of p endfor withcolor 625red The points are still located on the original path We can move the points to the inside by shifting them over the penwidth in the direction perpendicular to the point Because we use this transformation more than once we wrap it into a macro This also keeps the code readable vardef inside expr pnt of p point pnt of p shifted penoffset direction pnt of p of currentpen A few more details Page 174 Only this far enddef draw inside 0 of p for i 1
286. r loop header for symbolic token progression for symbolic token for list for symbolic token within picture expression forsuffixes symbolic token suffix list forever progression numeric expression upto numeric expression numeric expression downto numeric expression numeric expression step numeric expression until numeric expression for list expression for list expression METAPOST syntax Page 579 Syntax diagrams suffix list gt suffix suffix list suffix Left overs There are a few more concepts and commands available in METAFUN like color remapping shading and graphic inclusion Because they have their own small syntax world we present them here You may consider shades to be internally represented by a hidden datastructure The end user has access to a shade by means of a pointer expressed in a numeric pseudo procedure linear _shade path expression numeric expression color expression color expression circular _shade path expression numeric expression color expression color expression pseudo function define _linear _shade pairexpr pairexpr colorexpr color expr define _circular _shade pair expr pair expr path expr pathexpr color expr color expr predefined _linear _shade path expr numeric expr color expr color expr
287. r red randomseed seed p Field Text Text enlarged if alternative 1 48pt superellipsed superness elseif alternative 2 48pt squeezed squeezeness elseif alternative 3 36pt randomized randomness else 48pt fi transformed t def right_menu_button expr nn rr pp xx yy ww hh dd if pp gt 0 and rr gt 0 q rightsuperbutton p xx yy RightEdgeWidth hh fill q withcolor MPcolor white draw q withcolor if rr 2 MPcolor gray else MPcolor red fi fas enddef MPmenubuttons right Defining styles StopPage stopuseMPgraphic When we choose the alternatives 21 and 22 we get this result N Douglas R Hofstadter Donald E Knuth A Few Nice Quotes ne ew Ni Douglas R Hofstadter Donald E Knuth A Few Nice Quotes oe content index reference Page 470 Simple drawings A few applications For those who need to be inspired we will demonstrate how metarost can be used to enhance your document with simple graphics In these examples we will try to be not too clever simply because we lack the experience to be that clever The real tricks can be found in the files that come with METAPOST Simple drawings In the words of John Hobby the creator of metarost MeTAPOST is particularly well suited for generating figures for technical documents where some aspects of a picture may be controlled by mathematical or geo metrical constraints that are best expressed symbolically In othe
288. r words MetarosT is not meant to take the place of a freehand drawing tool or even an interactive graphics editor An example of such a picture is the following one which is dedicated to David Arnold who asked me once how to draw a spring So imagine that we want to draw a schematic view of a system of four springs A few applications Page 471 Simple drawings A rather natural way to define such a system is zi 2cm 0 z2 0 2cm z3 2cm 0 z4 0 2cm pickup pencircle scaled 1 5pt drawoptions withcolor 625red draw spring z1 75cm 10 draw spring z2 75cm 9 draw spring z3 75cm 8 draw spring z4 75cm 7 A few applications Page 472 Simple drawings Here the macro spring takes 5 arguments two points the width of the winding the length of the connecting pieces and the number of elements half windings The definition of spring is less complicated than readable def spring expr a b w h n 0 for i 1 upto n 1 if odd i fi w 2 ith endfor O nth 0 n 2h yscaled xpart b a ypart b a n 2h rotatedaround origin 90 angle b a shifted a enddef First we build a path starting in the origin going left or right depending on the counter being an odd number pat 0 0 for i 1 upto n 1 if odd i paw c pete 9 27 else pat pat w 2 i fan endfor pat pat 0 n A few applications
289. rDistance TextHeight FooterDistance FooterHeight BottomDistance BottomHeight horizontal LeftEdgeWidth LeftEdgeDistance LeftMarginWidth LeftMarginDistance TextWidth RightMarginDistance RightMarginWidth RightEdgeDistance RightEdgeWidth Since using these variables to construct paths is not that handy the areas are available as predefined paths which we will demonstrate here Page backgrounds Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into matize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus I came to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by
290. raphics are available Embedded graphics Page 221 Common definitions When you are using the web2c distribution CONTEXT can call MeTAPosT at runtime and thereby use the right graphics instantaneously In order to use this feature you have to enable write18 in the file texmf cnf Also in the file cont sys tex that holds local preferences or in the document source you should say runMPgraphicstrue This enables runtime generation of graphics using the low level TeX command write18 First make sure that your local brand of Tpx supports this feature A simple test is making a Tpx file with the following line immediate write1l8 echo It works If this fails you should consult the manual that comes with your system locate an expert or ask around on the CONTEXT mailing list Of course you can also decide to let T XEXEC take care of processing the graphics afterwards This has the advantage of being faster but has the disadvantage that you need additional Tpx runs If you generate the graphics at run time you should consider to turn on graphic slot recycling which means that you often end up with fewer intermediate files recycleMPslotstrue There are a few more low level switches and features but these go beyond the purpose of this manual Some of these features like the option to add tokens to everyMPgraphic are for experts only and fooling around with them can interfere with existing features Embedded graphics
291. rawcolor 625red withfillcolor 625white withpen pencircle scaled 1 5pt Special effects Page 371 Overview Functions METAPOST provides a wide range of functions like sind and floor We will discuss most of them here and define a few more We will also introduce a few methods for drawing grids and functions Overview What follows is a short overview of the functions that can be applied to numeric expressions and strings Functions that operate on pairs colors paths and pictures are discussed in other chapters First of all we have and For as far as is reasonable you can apply these to numerics pairs and colors Strings can be concatenated by amp Pythagorean addition is accomplished by while Pythagorean subtraction is handled by The opera tor gives you exponentiation The nature of the meTArost language is such that you can easily define interesting functions using such symbols The logarithmic functions are based on bytes This makes them quite accurate but forces you to think like a computer mexp x expential function with base 256 mlog x logarithm with base 256 The basic goniometric functions operate on degrees which is why they have a d in their name Functions Page 372 Overview cosd x cosine of x with x in degrees sind x sine of x with x in degrees There are three ways to truncate numbers The round function can also handle pairs and colors cei
292. rce of much unknown confusion When Tpx users talk about a 10pt font a desktop publisher hears 10bp Ina similar vein when we define a papersize having a width of 600pt and a height of 450pt which is papersize S6 in CONTEXT a POSTSCRIPT or PDF viewer will report slightly smaller values as page dimensions This is because those programs claim the pt to be a bp This confusion can lead to interesting discussions with desktop publishers when they have to use Tex They often think that their demand of a baseline distance of 13 4 is met when we set it to 13 4pt while actually they were thinking of 13 4bp which of course in other programs is specified using a pt suffix Therefore when embedding graphics in CONTEXT we strongly recommend that you use pt as the base unit instead The main reason why we spend so many words on this issue is that when neglected large graphics may look inaccurate Actually when taken care of it is one of the many reasons why Tx documents always look so accurate Given that the eye is sensitive to distortions of far less than 1pt you can be puzzled by the fact that many drawing programs only provide a bounding box in rounded units Thereby they round to the next position to prevent unwanted cropping For some reason this low resolution has made it into the high end POSTSCRIPT standard In CONTEXT we try to deal with these issues as well as possible Scaling and shifting When we draw a shape meTtarost will ada
293. rcle scaled 5pt s enddef To make our lives more easy we also define a macro that draws the dot as well as a macro that draws the label vardef freedotlabel expr str loc ori drawdot loc draw thefreelabel str loc ori enddef vardef freelabel expr str loc ori draw thefreelabel str loc ori enddef Now we get A few applications Page 482 Free labels The original label macros permits us to align the label at positions 4 corners and 4 points halfway the sides It happens that circles are also composed of 8 points Because in most cases the label is to be positioned in the direction of the center of a curve and the point at hand it makes sense to take circles as the starting points for positioning the labels To help us in positioning we define a special square path freesquare This path is constructed out of 8 points that match the positions that are used to align labels path freesquare freesqmene EC CFO Gil Cal 1 0 1 1 0 1 1 1 cycle scaled 5 We now show this free path together with a circle using the following definitions drawpath fullcircle scaled 3cm drawpoints fullcircle scaled 3cm drawpointlabels fullcircle scaled 3cm currentpicture currentpicture shifted 5cm 0 drawpath freesquare scaled 3cm drawpoints freesquare scaled 3cm drawpointlabels freesquare scaled 3cm We use two drawing macros that are part of the suite
294. refore for graphics that don t change CONTgXT provides reusable graphics startreusableMPgraphic name fill fullcircle scaled 200pt withcolor 625yellow stopreusableMPgraphic This definition is accompanied by reuseMPgraphic name Imagine that we use a graphic as a background for a button We can create a unique and reusable graphic by saying Embedded graphics Page 205 Integrated graphics def MyGraphic startreusableMPgraphic name overlaywidth overlayheight path p p unitsquare xscaled OverlayWidth yscaled OverlayHeight fill p withcolor 625yellow draw p withcolor 625red stopreusableMPgraphic reuseMPgraphic name overlaywidth overlayheight Notice the use of OverlayWidth and OverlayHeight These variables are set for each call to METAPOST After this we can say defineoverlay my graphic MyGraphic button background my graphic frame off Go Home firstpage Say that we have a 30pt by 20pt button then the identifier will be name 30pt 20pt Different dimensions will lead to other identifiers so this sort of makes the graphics unique We can bypass the ugly looking def by using a third class of embedded graphics the unique graphics startuniqueMPgraphic name path p p unitsquare xscaled OverlayWidth yscaled OverlayHeight fill p withcolor 625yellow draw p withcolor 625red stopuniqueMPgraphic Embedded graphics Page 206 Integrated graphics Now we can say
295. ression pair expression remapcolor color expression color expression resetcolormap recolor picture expression point number list suffix point number list suffix label suffix empty 1ft rt top bot ulft urt 11ft lrt raw origin content index reference command clip picture variable to path expression interim internal variable right hand side let symbolic token symbolic token pickup expression randomseed numeric expression save symbolic token list setbounds picture variable to path expression shipout picture expression special string expression addto command drawing command font metric command newinternal command message command mode command show command special command tracing command show command show expression list showvariable symbolic token list showtoken symbolic token list showdependencies content index reference symbolic token list symbolic token symbolic token symbolic token list expression list expression expression list expression addto command addto picture variable also picture expression option list addto picture variable contour path expression option list addto picture variable doublepath path expression option list option list empty draw
296. rests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into idealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chunk average approximate cluster aggregate outline sum marize itemize review dip into flip through browse glance into leaf through skim refine enumerate glean synopsize winnow the wheat from the chaff and separate the sheep from the goats Donald E Knuth Thus Icame to the conclusion that the designer ofa new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful if itis too strongly influenced by a single person Once the initial des
297. rged numeric primary bottomenlarged numeric primary randomized numeric or pair or color primary cornered numeric or pair METAPOST syntax Page 565 Syntax diagrams smoothed numeric or pair sqeezed numeric or pair primary superellipsed numeric primary randomshifted numeric or pair primary uncolored color primary softened numeric or color primary numeric or pair primary numeric primary pair primary numeric or pair or color primary numeric primary pair primary color primary numeric or color primary numeric primary color primary nullary op false normaldeviate nullpen nullpicture pencircle true whatever METAPOST syntax Page 566 Syntax diagrams unary op gt type abs acos acosh angle arclength ASCII asin asinh atan bbox blackpart bluepart bot bottomboundary bounded boundingbox cotd cyanpart cycle dashpart decimal ddecimal dddecimal dir exp ceiling center char clipped colormodel condition cosd cos cosh cot filled floor fontpart fontsize grayed greenpart greypart hex innerboundingbox inv invcos inverse inverted invsin known leftboundary length 1ft llcorner 1n log lrcorner magentapart makepath makepen mexp mlog not oct odd outerboundingbox pathpart penpart redpart reverse right
298. riable is useful We need to store the random seed value because we want the larger path that is used in the calculations to have the same shape alternative MPvarfalternative seed uniformdeviate 100 Defining styles Page 467 Adaptive buttons if alternative OMS superness 85 realfolio 1 lastpage 25 squeezeness 12pt realfolio 1 lastpage 10pt elise superness 80 squeezeness 12pt wa g randomness squeezeness alternative alternative mod 10 If you read closely you will notice that when we add 10 to the alternative we get a page dependant graphic So in fact we have five alternatives We use CONTEXT macros to fetch the real page number and the number of the last page In further calculations we use the lower alternative numbers which is why we apply a mod The rest of the code is not so much different from the previous definition The hard coded point sizes match the page dimensions 600pt by 450pt quite well t identity if alternative 3 shifted 9pt 9pt fi randomseed seed p Field Text Text enlarged if alternative 1 36pt superellipsed superness elseif alternative 2 36pt squeezed squeezeness elseif alternative 3 36pt randomized randomness else Defining styles Page 468 Adaptive buttons 36pt pickup pencircle scaled 3pt fill Page withcolor MPcolor yellow fill p withcolor MPcolor white draw p withcolor MPcolo
299. rk Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed butin my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font even Page 295 Crossing borders Edward R Tufte We thrive in information thick worlds because of our marvelous and everyday capacity to select edit single out structure highlight group pair merge harmonize synthesize focus organize condense reduce boil down choose categorize catalog classify list abstract scan look into idealize isolate discriminate distinguish screen pigeonhole pick over sort integrate blend inspect filter lump skip smooth chunk average approximate cluster aggregate outline sum marize itemize review dip into flip throu
300. ro This macro takes two or more paths and calculates the combined path Although this is a rather clever macro you should be prepared to help it a bit when paths have multiple intersection points Again we could follow a more secure mathematical method but the next one took only a few minutes of trial and error To save some memory we redefine the colors graphic When we call this macro as colorcircle 4cm red green blue we get A few applications Page 501 Color circles vardef colorcircle expr size red green blue save r g b rr gg bb cc mm yy save radius path r g b rr bb gg cc mm yy numeric radius radius 5cm pickup pencircle scaled radius 25 b fullcircle scaled radius shifted 0 radius 4 rotatedaround origin 15 rotatedaround origin 135 rotatedaround origin 255 r rotatedaround center r 90 g rotatedaround center g 90 gg buildcycle buildcycle reverse r b g A few applications Page 502 Color circles buildcycle buildcycle b reverse g r gg rotatedaround origin 120 gg rotatedaround origin 240 rotatedaround origin 120 rotatedaround origin 240 fill fullcircle scaled radius withcolor white fill rr withcolor red fill cc withcolor white red fill gg withcolor green fill mm withcolor white green fill bb withcolor blue fill yy withcolor white blue for i rr gg bb cc mm yy draw i withcolor 5white endfor
301. rrange these to cycle manually with clicks of the mouse through the sequence of graphs depicting the construction of the midpoint of segment A B So in fact we are dealing with a manual simulation The definition of such a stack is as follows def inefieldstack midpoint construction step 1 step 2 step 3 step 4 step 5 frame on offset 3pt framecolor darkyellow rulethickness 1pt The first argument is to be a unique identifier the second argument takes a list of symbols while the third argument accepts settings More on this command can be found in the CONTeXT manuals The stack is shown as figure 13 6 Its caption provides a button which enables the reader to cycle through the stack We call this a stack because the graphics are positioned on top of each other Only one of them is visible at any time placefigure here fig steps Bisecting a line segment with compass and straightedge Just click goto here JS Walk_Field midpoint construction to walk through the construction This stack is only visible A few applications Page 530 Growing graphics in a PDF viewer that supports widgets fieldstack midpoint construction Figure 13 6 Bisecting a line segment with compass and straightedge Just click here to walk through the construction This stack is only visible in a PDF viewer that supports widgets At the start of this section we mentioned three methods When we use the first method of put
302. rrow 0 0 10 0 withpen pencircle scaled 2pt withcolor red randomized 4 9 currentpicture currentpicture scaled 8 The arrow is made up out of two pieces and each piece gets a different shade of red This is because the attributes are collected and applied to each of the components that make up the arrow Because for each A few more details Page 195 Pitfalls component the attribute code is expanded again we get two random colors One way around this is to apply the color afterwards draw image drawarrow 0 0 10 0 withpen pencircle scaled 2pt scaled 8 withcolor red randomized 4 9 Here the image macro creates a picture and as you can see this provides a way to draw within a draw operation Once you see the benefits of image you will use it frequently Another handy at first sight strange macro is hide You can use this in situations where you don t want code to interfere def mydraw text t boolean error error false def withpencil expr p hide error true enddef draw t if error message pencils are not supported here fi enddef mydraw fullcircle scaled 10cm withpencil sharp Here setting the boolean normally interferes with the draw operation but by hiding the assignment this code becomes valid This code will bring the message to your terminal and log file A few more details Page 196 Pitfalls Once you start using expressions you have a good chance of enco
303. rve elseif anglemethod 2 A few applications Page 496 middle common rotatedaround 5 pointa pointb 180 curve pointa middle pointb elseif anglemethod 3 curve pointa middle pointb elseif anglemethod 4 curve pointa controls middle pointb middle point 5 along curve a draw thefreelabel str middle common withcolor black curve enddef E method 1 method 2 method 3 Figure 13 1 Three ways of marking angles A few applications Marking angles Figure 13 1 shows the first three alternative methods implemented here Instead of using unitvectors we now calculate the points using the arctime and arclength primitives Instead of complicated expressions we use the METAFUN operators along and on The following expressions are equivalent pointa point anglelength ona middle point 5 along curve pointa point arctime anglelength of a of a middle arctime 5 arclength curve of curve of curve The third method can be implemented in different more math intensive ways but the current implementation suits rather well and is understood by the author Color circles In chapter 3 we showed a few color circles Drawing such a graphic can be done in several ways and here we will show a few methods First we will demonstrate how you can apply cutafter and cutbefore next we will show how the metarosT macro buildpath can be used and finally we will present a cl
304. s Page 493 Marking angles Because in most cases we want the length to be consistent between figures and because passing two paths is more convenient than passing three points the final definition looks slightly different numeric anglelength anglelength 20pt vardef anglebetween expr a b str path path string save endofa endofb common curve where pair endofa endofb common path curve numeric where endofa point length a of a endofb point length b of b if round point O of a round point O of b common point 0 of a else common a intersectionpoint b wa lt p where turningnumber common endofa endofb cycle curve unitvector endofa common endofa common rotated where 90 unitvector endofb common scaled anglelength shifted common draw thefreelabel str point 5 of curve common withcolor black curve enddef This macro has a few more if s than its predecessor First we test if the label is a string and if so we calculate the picture ourselves otherwise we leave this to the user Pat hia mpre ede a origin 2cm icm b origin len 2cm A few applications Page 494 Marking angles c origin 2cm 2cm d origin 2cm 1cm e origin 1cm 2cm f origin 1cm 2cm for i a b c d e f drawarrow i endfor anglelength 1 0cm drawoptions withcolor 625red drawarrow anglebetween a b btex alpha etex
305. s a collection of variables of the same type that are assigned and accessed by indexing the variable name as inn 3 5 Multi dimensional arrays are also supported Since you need a bit of imagination to find an application for 5 dimensional arrays we restrict ourselves to a two dimensional example numeric n n 2 3 10 A nice feature is that the bounds of such an array needs not to be set beforehand This also means that each cell that you access is reported as unknown unless you have assigned it a value Welcome to MetaPost Page 53 Conditions Behind the screens there are not really arrays It s just a matter of creating hash entries It might not be obvious but the following assignments are all equivalent i_111_222 1Icm a_ Eilalill _ 222 2 ilem 8 i_ 111 222 1cm draw image draw Ocm i_111_222 draw 1cm i_ 111 _ 222 draw 2cm i_ 111 222 withpen pencircle scaled 5mm withcolor 625 red Sometimes METAPOST ways are mysterious Conditions The existence of boolean variables indicates the presence of conditionals Indeed the general form of META Post s conditional follows alzi i draw jo GSS amp Cheeky 3 wa fF Welcome to MetaPost Watch the colons after the if and else clause They may not be omitted The semi colons on the other hand are optional and depend on the context You may say things like draw if n 10 p else q fi Here we can omit
306. s compares well to the text as typeset by TEx MetaPost is Fun We can now use the values in pos to position the pictures according to what Tpx considered to be the best relative position startMPdrawing for i 1 upto n draw pic i shifted pos i 0 draw boundingbox pic i shifted pos i 0 withpen pencircle scaled 25pt withcolor red endfor stopMPdrawing Typesetting in METAPOST Page 402 TEX text That this correction is adequate is demonstrated in the next graphic If you look closely you will see that for instance the o is moved to the left under the capital P MetaPost is Fun When we want to position the pictures along a circle we need to apply some rotations especially because we want to go clockwise Since we don t want to use complicated math or more advanced metarost code yet we will do it in steps startMPdrawing for i 1 upto n picli pic i rotatedaround origin 270 endfor stopMPdrawing gt Crh One nan SS We will now center the pictures around the baseline Centering comes down to shifting over half the height of the picture This can be expressed by ypart 5 ulcorner pic i llcorner pic i but different ways of calculating the distance are possible too Typesetting in METAPOST startMPdrawing for i 1 upto n pic i pic i shifted 0 ypart 5 ulcorner pic i llcorner pic i endfor stopMPdrawing So now we have
307. s dedicated to the basic extensions to METAPOST as provided by METAFUN Most of them are meant to make defining graphics like those shown in this document more convenient Many of the concepts introduced here will be discussed in more detail in later chapters So you may consider this chapter to be an appetizer for the following chapters If you want to get started quickly you can safely skip this chapter now Paths Paths are the building blocks of metarost graphics In its simplest form a path is a single point content index reference Page 10 Paths 1cm 1 5cm e Such a point is identified by two numbers which represent the horizontal and vertical position often referred to as x and y or x y Because there are two numbers involved in metarost this point is called a pair Its related datatype is therefore pair The following statements assigns the point we showed previously to a pair variable pair somepoint somepoint 1icm 1 5cm A pair can be used to identify a point in the two dimensional coordinate space but it can also be used to denote a vector being a direction or displacement For instance 0 1 means go up Looking through math glasses you may consider them vectors and if you know how to deal with them Metarost may be your friend since it knows how to manipulate them You can connect points and the result is called a path A path is a straight or bent line and is not necessarily a smooth curve
308. s layered way This means that as long as a graphic is not flushed you may consider it to be a stack of paths and texts with the paths being drawn or filled shapes or acting as clipping paths or bounding boxes When you ask for the dimensions of a graphic the lower left and upper right corner are calculated using this stack Because you can explicitly set bounding boxes you can lie about the dimensions of a graphic This is a very useful feature In the rare case that you want to know the truth and nothing but the truth you can tweak the truecorners numeric variable We will demonstrate this with a few examples fill fullcircle scaled 1cm withcolor 625yellow A few more details Page 127 Bounding boxes fill fullcircle scaled 1cm withcolor 625yellow setbounds currentpicture to boundingbox currentpicture enlarged 2mm fill fullcircle scaled 1cm withcolor 625yellow setbounds currentpicture to boundingbox currentpicture enlarged 2mm interim truecorners 1 fill fullcircle scaled 1cm withcolor 625yellow interim truecorners 1 setbounds currentpicture to boundingbox currentpicture enlarged 2mm gt A few more details Page 128 Units As you can see here as soon as we set truecorners to 1 the bounding box settings are ignored There are two related macros bbwidth and bbheight that you can apply to a path fill unitcircle xscaled 4cm yscaled 2c
309. s well as providing me the hooks I considered neccessary for implementing some of the features presented here I also want to thank David Arnold and Ton Otten for their fast proofreading for providing me useful input and for testing the examples Without David s patience and help this document would be far from perfect English and less complete Without Ton s help many small typos would have gone unnoticed This is the second version of this document The content has been adapted to CONTEXT MKIV that uses LUATEX and the built in metarost library Of course most still applies to MeTAaPosT in general and therefore to CONTEXT MKII as well Maybe some of the solutions presented here can be done easier in future versions of MKIV but it does not hurt to see the more general variants Hans Hagen Hasselt NL October 8 2010 Introduction Content Conventions 1 19 Cutting and pasting 1 20 Current picture 1 Welcome to MetaPost 2 A few more details Lil 1 2 Transformations 2 1 Making graphics 13 Constructing paths 2 2 Bounding boxes 14 Angles 2 3 1 5 Drawing pictures 24 Scaling and shifting 1 6 Variables 2 5 Curve construction 1 7 Conditions 2 6 Inflection tension and curl 1 8 2 7 Transformations I 2 8 Only this far 2 9 Directions 2 10 Analyzing pictures Joining lines 2 11 Pitfalls Colors 2 12 TRX versus METAPOST Dashes 2 13 Internals and Interims 3 Embedded hi Linear equations hema oe a Clipping 3 1 Getting start
310. scaled 6cm yscaled 2cm shifted 1 5cm 1cm withpen pencircle scaled 1 5mm withcolor white draw unitsquare shifted 5 5 xscaled 6cm yscaled 2cm withpen pencircle scaled 1mm withcolor black draw origin withpen pencircle scaled 1mm As you can see the transformations are applied in series Sometimes this is not what we want in which case we can use parentheses to force the desired behaviour The lesson learned is that scaling and shifting is not always the same as shifting and scaling content index reference draw Page 135 Scaling and shifting origin origin shifted 4cm 0cm shifted 4cm 0cm withpen pencircle scaled 1cm withcolor 625white draw origin origin shifted 4cm 0cm shifted 4cm 0cm withpen pencircle draw origin origin withpen pencircle draw origin origin withpen pencircle scaled 8mm withcolor 625yellow shifted 4cm 0cm shifted 4cm 0cm scaled 6mm withcolor 625red shifted 4cm 0cm shifted 4cm 0cm scaled 4mm withcolor white Especially when a path results from a call to a macro using parentheses around a path may help as in the following example def unitslant origin origin shifted 1 1 enddef draw unitslant xscaled 5cm yscaled icm withpen pencircle draw scaled 1cm withcolor 625red unitslant xscaled 5cm yscaled 1cm withpen pencircle scaled 5mm withcolor 625yellow A few more details Page 136 The next definition o
311. sed in z1 or 2234 vardef z x y enddef Other applications can be found in the label drawing macros where the anchor point is assigned to the obscure variable Pens When drawing three attributes can be applied to it a dashpattern a pen and or a color You may consider an arrowhead an attribute but actually it is just an additional drawing appended to the path The predefined pencircle attribute looks like withpen pencircle Welcome to MetaPost Page 65 Pens where pencircle is a special kind of path stored in a pen variable Like any path you can transform it You can scale it equally in all directions withpen pencircle scaled imm You can also provide unequal scales creating an elliptically shaped and rotated pen withpen pencircle xscaled 2mm yscaled 4mm rotated 30 In the following graphic the circle in the center is drawn without any option which means that the default pen is used being a pencircle with a radius of half a base point The other three circles are drawn with different pen specifications If you forget about the colors the metarost code to achieve this is as follows content index reference Page 66 Pens path p p fullcircle scaled icm draw p draw p scaled 2 withpen pencircle draw p scaled 3 withpen pencircle scaled imm draw p scaled 4 withpen pencircle xscaled 2mm yscaled 4mm rotated 30 If this were the only way of specifying a pen we would be faced wi
312. ses as argument A Tex like solution for passing arbitrary content to such a graphic is the following It took the author a while to find out that there is a MetaPost module called tex mp that provides a similar feature but with the disadvan tage that each text results in a call to Tex Each text goes into a temporary file which is then included and results in metarosr triggering TEX content index reference Page 239 Graphics and macros def RotatedText 1 2 startuseMPgraphic RotatedText draw btex 2 etex rotated 1 stopuseMPgraphic useMPgraphic RotatedText This macro takes two arguments the identifies an argument RotatedText 15 Some Rotated Text The text is rotated over 15 degrees about the origin in a counterclockwise direction ae gome R In CONTEXT we seldom pass settings like the angle of rotation in this manner You can use setupMPvariables to set up graphic specific variables Such a variable can be accessed with MPvar setupMPvariables RotatedText rotation 90 startuseMPgraphic RotatedText draw btex Some Text etex rotated MPvar rotation stopuseMPgraphic content index reference Page 240 Graphics and macros An example RotatedText 15 Some Rotated Text Ina similar fashion we can isolate the text This permits us to use the same graphics with different settings setupMPvariables RotatedText rotation 270 setMPtext RotatedText Some Text startuseMPgraphic R
313. setlayer YourLayer position yes inframed Here here Here You can influence the placement by explicitly providing an offset hoffset and or voffset a position x and or y or a location directive location Normally you will use the offsets for the layer as a whole and the positions for individual contributions The next example demonstrates the use of a location directive here setlayer YourLayer position yes location c inframed Here heere Positional graphics Page 264 More layers Many layers can be in use at the same time In the next example we put something in the page layer By default we turn on position tracking which visualizes the bounding box of the content and shows the reference point definelayer BackLayer position yes setupbackgrounds page background BackLayer Next we define an overlay that we can put behind for instance framed texts We use METAPOST to draw Shape defineoverlay Shape BackLayer uniqueMPgraphic Shape startuniqueMPgraphic Shape path p p fullcircle xyscaled OverlayWidth OverlayHeight fill p withcolor MPcolor lightgray draw p withpen pencircle scaled 1pt withcolor MPcolor darkred stopuniqueMPgraphic We can now put this background shape behind the running text for instance with some inframed background Shape text with a frame some Shaped text with a frame some fo with a frame a The Shaped macro
314. sing setupinteraction state start content index reference setupbackgrounds page background color nextpage backgroundcolor darkyellow Here the page gets a colored background and a hyperlink to the next page previously defined by defineoverlay nextpage overlaybutton nextpage An overlaybutton is just a button with all attributes color frame etc set to nothing having the dimensions of the overlay The argument is one of the permitted destinations like nextpage firstpage SearchDocument and alike For efficiency reasons the background areas like text text are calculated only when their definition has changed When a background changes per page we have to recalculate it on each page In the next example the macro overlaybutton generates a different button on each page But since we don t explicitly set the background at each page there is no way the background drawing mechanism can know that this button has changed Therefore we must force recalculation with setupbackgrounds state repeat You can test this concept yourself with the following code Here we assume that you have a file called tufte tex on your system which is the case if you have CONT XT installed However you can just as eas ily use any file having a paragraph of two of text starttext setupinteraction state start Page backgrounds Page 289 Crossing borders setupbackgrounds state repeat defineoverlay n
315. sing the built in primitive nullpicture Later on we will add the drawn paths as accumulated in currentpicture to this finalpicture in the follow ing manner addto finalpicture also currentpicture shifted n 3cm 0 Since we want to add a few more and don t want them to overlap we shift them Therefore we have to erase the current picture as well as increment the shift counter currentpicture nullpicture n ntl The drawf ill macro is one of the METAFUN macros Another handy macro is boundingbox When used instead of bbox you don t have to set the margin to zero There is a subtle point in filling a shape In figure 2 2 you see the influence of the pen on a fill operation An indirect specification has no influence and results in a filled rectangle with sharp corners The third rectangle is drawn with a direct pen specification which results in a larger shape with rounds corners However the bounding box is the same in all three cases The graphic is defined as follows This time we don t use a complicated macro content index reference Page 126 Bounding boxes Figure 2 2 The influence of pens on fill drawoptions withcolor 625white path p p unitsquare scaled 2cm fill p shifted 3cm 0 pickup pencircle scaled 5cm fill p shifted 6cm 0 fill p shifted 9cm 0 withpen pencircle scaled 5cm When a graphic is constructed its components end up in an internal data structure in a more or les
316. sition macro MPpos returns the current characteristics of a position The previously defined G positions return position page x y width height depth G 1 259 168 33382pt 186 68945pt 31 97pt 7 26pt 2 83pt G2 259 516 34001pt 186 68945pt 21 15999pt 4 69pt 2 83pt G 3 259 154 09756pt 174 11743pt 27 68001pt 7 26pt 0 2pt G 4 259 232 33842pt 161 54541pt 16 46999pt 6 21pt 0 2pt The numbers represent the real pagenumber p the current position x y and the dimensions of the box w h d if known These values are fed directly into metaPost graphics but the individual components can be asked for by MPp MPx MPy MPw MPh and MPd In the previous definition of the graphic we saw another macro MPvar When we invoke a graphic or attach a graphic to a layer we can pass variables We can also set specific variables in other ways as we will see later Positional graphics Page 262 More layers setMPpositiongraphic G 1 mypos circle setMPpositiongraphic G 1 mypos line to G 2 In the second definition we let the variable to point to another position When needed we can ask for the value of to by MPvar to For reasons of convenience the current position is assigned automatically to from and self This means that in the line we saw in the graphic initialize_box MPpos MPvar self MPvar self will return the current position which fed to MPpos will return the list of positional numbers We already warned the r
317. st category will certainly grow Some of these modules are preloaded others can be loaded using the command useMPlibrary like useMPlibrary clp txt for loading the predefined clipping paths and text tricks The metAPosT code is organized in files named mp mp The core file is mp tool mp and this file can comfortably be used in stand alone graphics The file metafun mp is used to load the collection of modules into a format The collection of Metarost code files will grow in due time but as long as you use the METAFUN format you don t have to keep track of the organization of files Most files relate to subsystems and are loaded automatically like the files that implement page layout support and flow charts Although this document is the main source of information occasionally the source code of METAFUN and in many cases the source code of CONTEXT may contain additional information and examples METAFUN macros Page 560 Syntax diagrams METAPOST syntax In the METAFONT book as well as the MeTaPost manual you can find the exact specification of the language Below you find the full metarost syntax to which we add the basic METAFUN extensions If this page looks too cryptic you can safely skip to the next chapter Syntax diagrams The following syntax diagrams are derived from the diagrams in the metarost manual The represents means and the symbol stands for or The diagrams describe the hard coded M
318. st make sure that the TEX environment of your document matches the one used by METAPOST We let the bodyfont match the font used in this document and define RotFont to be the regular typeface the one you are reading right now but bold definefont RotFont RegularBold Since MeTAPOST is unaware of kerning we have to use T X to keep track of the positions We will split the text into tokens often characters and store the result in an array of pictures pic We will also store the accumulated width in an array len The number of characters is stored in n In a few paragraphs we will see why the other arrays are needed Typesetting in METAPOST Page 398 TEX text While defining the graphic we need Tpx to do some calculations Therefore we will use startMPdrawing to stepwise construct the definition The basic pattern we will follow is resetMPdrawing startMPdrawing metapost code stopMPdrawing tex code startMPdrawing metapost code stopMPdrawing MPdrawingdonetrue getMPdrawing In the process we will use a few variables We will store the individual characters of the text in the variable pic its width in wid and the length of the string so far in len Later we will use the pos array to store the position where a character ends up The variable n holds the number of tokens resetMPdrawing startMPdrawing picture pic numeric wid len pos n wid 0 len 0 pos 0 n 0 stopMPdrawing
319. st to keep things readable we have to use vardef to hide the assignment for the outside world We demonstrate this macro using the following code pair a b c a 2cm icm b 3cm icm c 1cm 5cm drawarrow c a drawarrow c b drawarrow anglebetween a b c 0 75cm withcolor 625red drawarrow anglebetween b a c 1 50cm withcolor 625red Watch how both arrows point in the direction of the line that is determined by the second point We now have the framework of an angle drawing macro ready and can start working placing the label A few applications vardef anglebetween expr endofa endofb common length str save curve where path curve numeric where where turningnumber common endofa endofb cycle curve unitvector endofa common endofa common rotated where 90 unitvector endofb common scaled length shifted common draw thefreelabel str point 5 of curve common withcolor black curve enddef The macro thefreelabel is part of METAFUN and is explained in detail in section 13 2 This macro tries to place the label as good as possible without user interference pair a a 2cm 1cm drawarrow origin a pair b b 3cm 1cm drawarrow origin b drawarrow anglebetween a b origin icm btex alpha etex withcolor 625red Instead of a picture we may also pass a string but using Tx by means of btex etex often leads to better results he A few application
320. starts and ends Given that lines are horizontal and straight we therefore need to calculate the intersection points of the lines and the path As a first step we calculate the top and bottom of the path and after that we split off the left and right path startuseMPgraphic text split pair t b path 1 r Typesetting in METAPOST Page 420 Talking to Tex ulcorner p urcorner p intersectionpoint p llcorner p lrcorner p intersectionpoint p l p cutbefore t 1 1 cutafter b r p cutbefore b r r cutafter t stopuseMPgraphic The intersectionpoint macro returns the point where two paths cross If the paths don t cross an error is reported when the paths cross more times just one point is returned The cutafter and cutbefore commands do as their names say and return a path In the text split code fragment t and b are the top points of the main path while 1 and r become the left and right half of path p We now draw the original path using a thick pen and both halves with a thinner pen on top of the original The arrows show the direction startuseMPgraphic text draw draw p withpen pencircle scaled 3pt withcolor red drawarrow 1 withpen pencircle scaled 1pt withcolor green drawarrow r withpen pencircle scaled ipt withcolor blue stopuseMPgraphic We use includeMPgraphic to assemble the components startuseMPgraphic text includeMPgraphic text path content index reference
321. t use no real tricks Opposite to the next feature which is implemented using the Metarost special driver that comes with CONTEXT METAPOST is not really meant for manipulating graphics but the previous examples demonstrated that we have some control over individual colors In the next series of examples we will treat the picture as a whole First we invert the colors using inverted loadfigure gracht mp number 1 scaled 5 addto currentpicture also inverted currentpicture shifted bbwidth currentpicture 5cm 0 Special effects exit dex i lt D D Changing colors This is a special case of uncolored In the next example we explicitly specify the color loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture uncolored green shifted bbwidth currentpicture 5cm 0 Special effects lt content index reference lt lt gt You can also multiply each color using softened In the next sample the colors have 80 of their value loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture softened 8 shifted bbwidth currentpicture 5cm 0 You can also use this operator to harden colors simply by providing a value larger than 1 Keep in mind that colors are clipped at 1 anyway loadfigure gracht mp number 1 scaled 5 addto currentpicture also currentpicture softened 1 2 shift
322. t 4 y4 z4 width 0 z5 x4theight 2 y1 z6 x4 2y1 vil lell 5 pachipi 5 j 8 wil wV zs a 5 joeleln 8S Bsa 3 numeric d 1x ly ux uy d line 2 lx 3d d 3 ly d ux rt x5 d 3 uy top y6 path r r 1x ly ux ly ux uy 1x uy cycle ibg g ibe clellise 3 ily s liyeclellice 3 wee g werclellsa why uy de ital path s s 1x ly ux ly ux uy 1x uy cycle draw p withcolor nsblue draw q withcolor nsblue addto currentpicture also currentpicture rotatedaround 5 z2 z3 180 shifted height 4 height 2 picture savedpicture savedpicture currentpicture A few applications Page 542 Music sheets clip currentpicture tor setbounds currentpicture to r savedpicture currentpicture currentpicture nullpicture fill s withcolor nsyellow addto currentpicture also savedpicture For practical use it makes sense to package this definition in a macro to which we pass the dimensions Music sheets The next example demonstrates quite some features Imagine that we want to make us a couple of sheets so that we can write a musical masterpiece Let s also forget that Tx can draw lines which means that somehow we need to use METAPOST Drawing a bar is not that complicated as the following code demonstrates startusableMPgraphic bar vardef MusicBar expr width gap linewidth barwidth image interim lineca
323. t segment is determined by the following points point z of the curve the postcontrol point z2 of z the precontrol point z3 of z4 point z4 of the curve On the next pages we will see how the whole curve is constructed from these quadruples of points The process comes down to connecting the mid points of the straight lines to the points mentioned We do this three times which is why these curves are classified as third order approximations The first series of graphics demonstrates the process of determining the mid points The third order midpoint is positioned on the final curve The second series focuses on the results new sets of four points that will be used in a next stage The last series only shows the third order midpoints As you can see after some six content index reference Page 139 Curve construction iterations we have already reached a rather good fit of the final curve The exact number of iterations depends on the resolution needed You will notice that the construction speed density differs per segment The path in these examples is defined as follows path p p 4cm 4cm 6cm 0cm 1cm 2cm If you are playing with graphics like this the METAFUN macro randomize may come in handy p p randomized 1cm 5cm If we apply this operation a couple of times we can see how the control points vary Using the randomizer saves us the troubles of finding nice example values The angle between the tangent as w
324. t the rules of typography from books from computer magazines or the instruction manuals which they get with the purchase of a PC or software StopFrame The implementation is not that complicated and uses the frame commands that are built in CONTEXT Instead of letting Tex draw the frame we use METAPOST which we also use for handling the title The graphic is defined as follows startuseMPgraphic FunnyFrame picture p numeric w h o p textext rt MPstring FunnyFrame w OverlayWidth h OverlayHeight o BodyFontSize p p shifted 20 h ypart center p draw p drawoptions withpen pencircle scaled 1pt withcolor 625red draw 20 h 0 h 0 0 w 0 w h xpart urcorner p h draw boundingbox p setbounds currentpicture to unitsquare xyscaled w h stopuseMPgraphic Because the framed title is partly positioned outside the main frame and because the main frame will be combined with the text we need to set the boundingbox explicitly This is a way to create so called free figures where part of the figure lays beyond the area that is taken into account when positioning the graphic The shift shifted 20 h ypart center p content index reference Page 246 Graphics and macros ensures that the title is vertically centered over the top line of the main box The macros that use this graphic combine some techniques of defining macros using predefined CONTEXT classes and passing information to grap
325. t with context timing yourdoc tex Functions Page 387 Drawing functions then you can afterwards process a file that is generated while processing this document context extras timing yourdoc This will give you a document with graphics that show where LUAT X spent its time on Of course these graphics are generated with METAPOST There are a few helpers built in and more might follow For example draw ctxlua metapost metafun topath x 1 y 1 x 1 y 3 4 1 cycle xysized 4cm 3cm withpen pencircle scaled imm withcolor 625 red The topath function takes a table of points or strings You can pass a connector so Functions Page 388 Drawing functions draw ctxlua metapost metafun topath x 1 y 1 x 1 y 3 4 1 cycle xysized 4cm 3cm withpen pencircle scaled imm withcolor 625 red Writing such LUA functions is no big deal For instance we have available function metapost metafun interpolate f b e s c tex write for i b e e b s do local d loadstring string format return function x return s end f if d then d dQ if i gt b then tex write c or Functions end tex write string format s 8 i d i end end tex write end An example of usage is draw ctxlua metapost metafun interpolate math sin x72 2 x math sqrt math abs x math pi 2 math pi 2 100 xysized 6cm 3cm withpen pencircle scaled 1mm withcolor
326. tO by count2 advance countO by count4 count4 hskip fancyplied 3 pt This is because Tx is very strict in what tokens it expects next In MeTtapost however you can use vardef d macros to hide nasty intermediate calculations vardef fancyplied expr x if x 0 message x is zero x x 2x x 2 enddef a a shifted fancyplied 3pt 0 In ex the calculation can be done in less lines using a numexpr A few more details Page 198 TEX versus METAPOST Hiding intermediate calculations and manipulations is a very strong point of METAPOST Another important difference between both languages is the way grouping is implemented Because Tpx is dealing with a flow of information strong grouping is a must and therefore part of the language Occasionally you run into situations where you wished that you could reach over a group for instance in order to pass a value In METAPOST grouping behaves quite different First of all it provides the mechanism that hides processing from the current flow The previously mentioned vardef is implicitly grouped Contrary to Tex in METAPOST all assignments are global by default even in a group If you assign a variable inside a group it is persistent unless you first save the variable or macro using the save operator So in the next code snippet the value of value inside the box is no but after the box is typeset it will be yes again def value yes hbox def value no val
327. ta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed but in my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font odd Figure 6 4 A background with enlarged text area the corners of those Page backgrounds startuseMPgraphic page StartPage path Main if OnRightPage Main lrcorner Field OQuterMargin Text llcorner Field Text Text ulcorner Field Text Text urcorner Field QuterMargin Text llcorner Field OuterMargin Text lrcorner Field Text Text urcorner Field Text Text ulcorner Field QuterMargin Text fag Main Main enlarged 6pt pickup pencircle scaled 2pt fill Page withcolor 625white fill Main withcolor 850white draw Main withcolor 625red StopPage stopuseMPgraphic In this definition we calculate a different path for odd and even pages When done we enlarge the path a bit If you want to use different offsets in all directions you can use moved corner points Page bac
328. tate slant and manipulate such a label picture like any other picture ethe right way The font can be specified in the string defaultfont and the scale in defaultscale Labels are defined using the low level operator infont The next statement returns a picture draw this string will become a sequence of glyphs MP infont defaultfont scaled defaultscale By default the infont operator is not that clever and does not apply kerning Also typesetting math or ac cented characters are not supported The way out of this problem is using btex etex draw btex this string will become a sequence of glyphs TeX etex The difference between those two methods is shown below The outcome of infont depends on the current setting of the variable defaultfont Welcome to MetaPost this string will become a sequence of glyphs MP this string will become a sequence of glyphs TEX When you run inside CONTEXT as we do here there is no difference between infont and the Tx methods This is because we overload the infont operator and also pass its content to TeX Both infont and btex use the macro textext which is intercepted and redirects the task to TeX This happens in the current run so there is no need to pass extra information about fonts Instead of passing strings to infont you can also pass characters using char for example char 73 When you use infont you normally expect the font to be ASCII conforming If this is not the case
329. ted 0 strutheight cycle withcolor 5white fill 111 rrr rrr shifted 0 strutdepth 111 shifted 0 strutdepth cycle withcolor 7white draw 111 withpen pencircle scaled 2pt draw rrr withpen pencircle scaled 2pt draw 11l rrr withpen pencircle scaled 5pt stopuseMPgraphic startuseMPgraphic text done endfor stopuseMPgraphic The result is still a bit disappointing startuseMPgraphic text includeMPgraphic text path includeMPgraphic text vars includeMPgraphic text move includeMPgraphic text split includeMPgraphic text cutoff includeMPgraphic text draw includeMPgraphic text calc includeMPgraphic text step includeMPgraphic text line includeMPgraphic text done stopuseMPgraphic Typesetting in METAPOST Page 429 Talking to Tex lt In order to catch the overflow at the bottom we need to change the for loop a bit so that the number of lines does not exceed the available space The test that surrounds the assignment of vvsize makes sure that we get better results when we on purpose take a smaller height startuseMPgraphic text step path line pair 111 rrr numeric vvsize if strutheight strutdepth lt baselineskip vvsize vsize elise vvsize vsize div baselineskip baselineskip wa g for i topskip step baselineskip until vvsize line ulcorner q urcorner q shifted 0 i Typesetting in METAPOST 111 found_point line l true
330. tension 1 Z2 zi tension 1 and 1 z2 The triple dot command is actually a macro that makes the following commands equivalent Both com mands will draw identical paths Zi oaa Z2 z1 tension atleast 1 z2 The atleast directive tells MeTaPosT to do some magic behind the screens Both the 3 4 and the atleast lead directly to the question What exactly is the influence of the tension directive We will try to demystify the tension specifier through a sequence of graphics u 1cm z1 0 0 z2 2u 4u z3 4u 0 def sample expr p c draw p withpen pencircle scaled 2 5mm withcolor white draw p withpen pencircle scaled 2 0mm withcolor c enddef for i 75 step 05 until 1 sample zi tension i z2 23 625red content index reference endfor for i 1 step 05 until 2 sample z1 tension i z2 z3 625yellow endfor sample zi z2 23 625white sample zi z2 23 625white Indeed values less than 75 give an error message but large values are okay As you can see the two gray curves are the same Here atleast 1 means 1 even if larger values are useful A few more details exit lt dd gt b gt Page 154 Inflection tension and curl Curves finally are made up out of points and each point has two control points Since the tension specifier finally becomes a control point it is not surprising that you may specify two tension values If we rep
331. tent like graphics This is only needed when the graphic is part of the text flow A Next we draw two circles of equal radius one centered at point A the other at point B startbuffer d def draw_circles path circleA circleB numeric radius distance distance xpart pointB xpart pointA radius 2 3 distance circleA fullcircle scaled 2 radius circleB circleA shifted pointB draw circleA draw circleB enddef stopbuffer These spacing commands try to get the spacing around the content visually compatible and take the height and depth of the preceding and following text into account A few applications As you can see we move down the stand_out macro so that only the additions are colored red startbuf fer 2 start_everything draw_basics stand_out draw_circles stop_everything stopbuffer We now use processMPbuffer a b c d 2 to include the latest step The next step in the construction of the perpendicular bisector requires that we find and label the points of intersection of the two circles centered at points A and B The intersection points are calculated as follows Watch the reverse operation which makes sure that we get the second intersection point startbuffer e def draw_intersection pair pointC pointD A few applications Page 523 Growing graphics pointC circleA intersectionpoint circleB pointD reverse circleA
332. th a considerable amount of typing par ticularly in situations where we use pens similar to the fourth specification above For that reason METAPOST supports the concept of a current pen The best way to set this pen is to use the pickup macro pickup pencircle xscaled 2mm yscaled 4mm rotated 30 This macro also stores some characteristics of the pen in variables so that they can be used in the more complicated calculations that are involved in situations like drawing font like graphics If we substitute pencircle by pensquare we get a different kind of shapes In the non rotated pens the top bottom left and right parts of the curve are thinner content index reference You should look at pens in the way an artist does He follows a shape and in doing so he or she twists the pen and thereby the nib and puts more or less pressure on it The chance that you have an appropriate pen laying at your desk is not so large but you can simulate the following mMeTAPOsST s pen by taking two pencils and holding them together in one hand If you position them in a 45 degrees angle and draw a circle you will get something like Welcome to MetaPost Page 68 Pens If you take a calligraphic pen with a thin edge of 5cm you will get You can define such a pen yourself path p p fullcircle xscaled 2cm yscaled 3cm pen doublepen doublepen makepen 0 0 3cm 3cm pickup doublepen draw p Here we define a
333. th two pairs points two radius and two colors The shade is distributed between the colors according to the radius Shading can hardly be called an easy issue The macros that we provide here are in fact simplifications which means that at a lower level one can do more advanced things Here we limit ourselves to the more common cases In the previous examples we used an arrow to indicate the direction and magnitude of the shade The next macro demonstrates the principles in a different way def test_shade expr a b ra rb pickup pencircle scaled 1m color ca ca MPcolorfa color cb cb MPcolor b color cc cc MPcolor c path pa pa fullcircle scaled 2ra shifted a path pb pb fullcircle scaled 2rb shifted b content index reference sh define_circular_shade a b ra rb ca cb fill pb withshade sh draw pb withcolor cc draw pa withcolor cc enddef The shade is distributed between two circles each with a radius and center point All four can be set but as the next calls demonstrate we can normally do with less which is why we provided the macro with less parameters test_shade origin origin Ocm icm test_shade origin origin 25cm 1cm test_shade origin origin 50cm 1cm Special effects Page 332 Shading test_shade origin origin shifted 25cm 0 Ocm 1cm test_shade origin origin shifted 25cm 0 25cm 1cm test_shade origin origin shifted
334. the first three shapes here we use a different path for the calculations and the drawing Watch carefully If instead of an offset we pass a path meTarost is able to calculate the right dimensions and offsets This is needed since we need these later on startuseMPgraphic test 4 numeric w h o def shape 0 0 w 0 0 amp w 0 0 75w o 5h w 20 h 0 amp w 20 h 0 0 h o cycle enddef h g 6cm 6pt path p p shape h g 6cm Opt path q q shape build_parshape p q 6pt 6pt baselinedistance strutheight strutdepth strutheight Typesetting in METAPOST Page 438 Libraries draw q withpen pencircle scaled ipt stopuseMPgraphic Since we also want these graphics as backgrounds we define them as overlays If you don t want to show the graphic you may omit this step defineoverlay test 1 useMPgraphic test 1 defineoverlay test 2 useMPgraphic test 2 defineoverlay test 3 useMPgraphic test 3 defineoverlay test 4 useMPgraphic test 4 As text we use a quote from Douglas R Hofstadter s book Metamagical Themas Questing for the Essence of Mind and Pattern Watch how we pass a list of shapes startshapetext test 1 test 2 test 3 test 4 forgetall as it says setupalign verytolerant stretch normal 7 input douglas Douglas R Hofstadter stopshapetext Finally we combine text and shapes Since we also want a background we use
335. the given dimensions Watch how the line width scales accordingly If you don t want this you can add the following line redraw currentpicture withpen pencircle scaled 2pt draw boundingbox currenpicture withpen pencircle scaled 5mm Watch how the boundingbox is not affected PILI YO Welcome to MetaPost In this example we also used bbwidth which has a companion macro bbheight You can apply this macro to a path or a picture In fact you don t always need to follow this complex route if you want to simply redraw a path with another pen or color draw fullcircle scaled icm withcolor 625red withpen pencircle scaled imm draw currentpicture withcolor 625yellow withpen pencircle scaled 3mm draw boundingbox currentpicture withpen pencircle scaled 5mm This is what you will get from this If you want to add a background color to a picture you can do that afterwards This can be handy when you don t know in advance what size the picture will have fill fullcircle scaled icm withcolor 625red addbackground withcolor 625 yellow The background is just a filled rectangle that gets the same size as the current picture that is put on top of it content index reference Cutting and pasting When enhancing or building a graphic often parts of already constructed paths are needed The subpath cutbefore and cutafter operators can be used to split paths in smaller pieces In order to do so we must know wh
336. tin my opinion the article is charmingly written as well However despite my overall enthusiasm for Knuth s idea and article there are some points in it that I feel might be taken wrongly by many readers and since they are points that touch close to my deepest interests in artificial intelligence and esthetic theory I felt compelled to make some comments to clarify certain important issues raised by The Concept of a Meta Font concept copyright Figure 6 1 Two examples of annoying backgrounds after blank big Page backgrounds Page 287 Multiple overlays width textwidth There is one drawback when your left and right margin have different dimensions the text will be scaled differently on odd and even pages Normally this is no problem for a draft As an alternative you can use the setuptexts command and wrap the graphic in a box with the right dimen sions using code like startuniqueMPgraphic copyright picture p p btex COPYRIGHT etex rotated 90 setbounds p to boundingbox p enlarged ipt draw p withcolor 8white xyscale_currentpicture the leftmarginwidth the textheight stopuniqueMPgraphic setuptexttexts margin uniqueMPgraphic copyright The graphic goes into the outer margin The second argument can be used to put something in the inner margin Multiple overlays You can stack overlays Consider the next case where we assume that you have enabled interaction support u
337. ting all the graphics in an external metarost file the following framework suits We assume that the file is called step mp and that it is kept by the user along with his document source We start with the definitions of the graphic steps These are the same as the ones shown previously def draw_basics enddef def draw_circles enddef A few applications Page 531 Growing graphics def draw_intersection enddef def draw_bisector enddef def draw_midpoint coo Cuatelelent def stand_out enddef We can safe some code by letting the _everything take care of the beginfig and endfig macros def start_everything expr n beginfig n enddef def stop_everything coo endif ipe Gmelelext 5 The five graphics now become start_everything 1 stand_out draw_basics stop_everything start_everything 2 draw_basics stand_out draw_circles stop_everything start_everything 3 draw_basics draw_circles stand_out draw_intersection stop_everything start_everything 4 draw_basics draw_circles draw_intersection stand_out Page 532 Simple Logos draw_bisector stop_everything start_everything 5 draw_basics draw_circles draw_intersection draw_bisector stand_out draw_midpoint stop_everything The definitions of the symbols now refer to an external figure definesymbol step 1 externalfigure step 1 definesymbol step 2 external
338. tion free path between these points unless the endpoint directions make this impossible To use the words of David Arnold a point of inflection is where a path switches concavity from concave up to concave down for example It is surprisingly difficult to find nice examples that demonstrate the difference between and as it is often impossible to honour the request for less inflection We will demonstrate this with a few graphics In the four figures on the next pages you will see that is not really suited for taming wild curves If you really want to make sure that a curve stays within certain bounds you have to specify it as such using control or intermediate points In the figures that follow the gray curves draw the random path using on top of yellow curves that use the connection As you can see in only a few occasions do the yellow inflection free curves show up For those who asked for the code that produces these pictures we now include it here We use a macro sample which we define as a usable graphic nearly all examples in this manual are coded in the document source startuseMPgraphic sample def sample expr rx ry path p q numeric n m r a b color c c MPcolor lightgray a S Sim 8 sS Aum 3 je g Bem 3 a gS 7 im aG a q unitsquare scaled r xyscaled n m shifted 5r 5r draw q withpen pencircle scaled b 4 withcolor 625yellow for i 1 upto n for j 1 upton
339. tive draw function 2 x sin x 0 2pi pi 40 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 red draw function 2 x sin 2x 0 2pi pi 40 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 green draw function 2 x sin 3x 0 2pi pi 40 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 blue ARO The next alternative uses a larger step and as a result in drawing mode 2 gives worse results Without the epsed it would have looked even worse in the end points draw function 2 x sin x 0 epsed 2pi pi 10 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 red Functions draw function 2 x sin 2x 0 epsed 2pi pi 10 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 green draw function 2 x sin 3x 0 epsed 2pi pi 10 scaled 2cm withpen pencircle scaled 5mm withcolor transparent exclusion 1 blue There are enough applications out there to draw nice functions like gnuplot for which Mojca Miklavec made a backend that works well with CONTgxT Nevertheless it can be illustrative to explore the possibilities of the CONTEXT LUATEX METAPOST combination using functions First of all you can use LUA to make paths and this is used in some of the debugging and tracing options that come with CONTEXT For instance if you process a documen
340. to the reader to figure out how the code should be changed to accomplish this The complete result is shown on the next page The euro symbol When Patrick Gundlach posted a nice meTAPosT version of the euro symbol to the CONTEXT discussion list he added the comment The official construction is ambiguous how thick are the horizontal bars How much do they stick out to the left Is this thing a circle or what Are the angles on the left side of the bars the same as the one on the right side The alternative below is probably not as official as his but permits a finetuning You are warned whatever you try the euro is and will remain an ugly symbol A few applications Page 546 The euro symbol A few applications Page 547 The euro symbol We use a couple of global variables to control the euro shape within reasonable bounds Then we define two circles Next we define a vertical line that we use in a couple of cut and paste operations Watch how the top left point of the outer circle determines the slant of the line that we use to slice the vertical bars boolean trace_euro trace_euro false vardef euro_symbol image begin_of_euro if unknown euro_radius euro_radius 2cm if unknown euro_width euro_width 3euro_radius 16 if unknown euro_r_offset euro_r_offset euro_width if unknown euro_l_offset euro_l_offset euro_radius 32 if unknown euro_l_shift euro_l_shift euro_r_offset if unknown
341. tpicture This circle looks like 4 We can now ask for some of the characteristics of currentpicture like its color We could write the values to the log file but it is more convenient to put them on paper label rt redpart amp decimal redpart p 4cm 5cm label rt greenpart amp decimal greenpart p 4cm Ocm label rt bluepart amp decimal bluepart p 4cm 5cm content index reference Here the amp glues strings together while the decimal operator converts a number into a string The result has no typographic beauty keep in mind that here we use meTaPosT to typeset the text but the result serves its purpose redpart 0 625 greenpart 0 bluepart 0 We can also ask for the path itself pathpart the pen penpart and the dashpattern dashpart but these can only be assigned to variables of the corresponding type A path can be stroked or filled in which case it is a cyclic path It can have a non natural bounding box be a clip path consist of line segments or contain text All these characteristics can be tested label rt filled label rt stroked label rt textual label rt clipped label rt bounded label rt cycle condition filled p 4cm 1 25cm condition stroked p 4cm 0 75cm condition textual p 4cm 0 25cm condition clipped p 4cm 0 25cm condition bounded p 4cm 0 75cm condition cycle pathpart p 4cm 1
342. two times After it is processed we recolor the currentpicture black and after that we add the original picture once again content index reference Reference In this chapter we will demonstrate most of the drawing related primitives and macros as present in plain METAPOST and METAFUN extensions If a path is shown and or a transformation is applied we show the original in red and the transformed path or point in yellow The small dark gray crosshair is the origin and the black rectangle the bounding box In some drawings in light gray we show the points that makeup the path This list describes traditional metarost and the stable part of METAFUN As METAPOST evolves new primitives are added but they are not always that relevant to us If you browse the METAFUN sources you will for sure notice more functionality then summarized here Most of that is meant for usage in CONTEXT and not exposed to the user Other macros are still somewhat experimental but might become more official at some point When METAPOST version 2 is ready this reference will be updated accordingly Paths Cy Gi metapost concept content index reference air pair Reference Page 587 Paths CORIO rn Geico en Glieep2 een let metapost macro OWE CE O n oo Gls 2 ooGly i metapost macro COTOS O G E metapost macro air pair 0 0 75 0 4 25 1 1 metapost macro O
343. typesetting along a given path This method is not only more robust and general it is also a more compact definition especially if we omit the tracing and testing code We use a familiar auxiliary definition The setstrut and strut commands ensure that the lines have the proper depth and height def processfollowingtoken 1 appendtoks 1 to MPtoks setbox MPbox hbox RotFont setstrut strut the MPtoks startMPdrawing n n 1 len n the wd MPbox stopMPdrawing startMPdrawing pic n btex RotFont setstrut strut 1 etex Typesetting in METAPOST Page 410 T X text pic n pic n shifted llcorner pic n stopMPdrawing The definition of followtokens is as follows Keep in mind that RotFont is defined in the MeTarosT environ ment You may notice that we have added a directive to include the Metarost graphic called followtokens Storing the path in a graphic container instead of using startMPdrawing is less sensitive for interference with other drawing processes def followtokens 1 vbox bgroup MPtoks emptytoks resetMPdrawing startMPdrawing includeMPgraphic followtokens picture pic numeric len n n 0 stopMPdrawing handletokens 1 with processfollowingtoken startMPdrawing numeric al pl at wid pos pair ap ad al arclength RotPath pl al len n n 1 for i 1 upton wid abs xpart lrcorner pic i xpart llcorner pic i pos len i wid 2 i 1 p
344. u reverse an operation This is a result from mapping to and from internal quantities sqr x log x ln x exp x pow x p inv x content index reference Page 374 Grids The following sine and cosine functions take radians instead of angles in degrees sin x asin x invsin x cos x acos x invcos x There are no tangent functions so we provide both the radian and degrees versions tan x tand x cot x cotd x Here are a couple of hyperbolic functions sinh x asinh x cosh x acosh x We end with a few additional string converters ddecimal x decimal representation of a pair dddecimal x decimal representation of a color condition x string representation of a boolean Grids Some day you may want to use METAPOST to draw a function like graphic In the regular Tex distributions you will find a module graph mp that provides many ways to accomplish this For the moment METAFUN does not provide advanced features with respect to drawing functions so this section will be relatively short Functions Page 375 Grids When drawing a functions for educational purposes we need to draw a couple of axis or a grid as well as a shape Along the axis we can put labels For this we can use the metarost package format mp but this does not integrate that well into the way METAFUN deals with text typeset by TEx For those who love dirty tricks and clever macros close reading of the code in format mp may be worthwh
345. ue value To make a value local in Metarosr the following code is needed string value value yes def intermezzo begingroup save value string value value no endgroup enddef Once you start writing your own METAPOST macros you will appreciate this always global behaviour As with other differences between the two languages they make sense if you look at what the programs are supposed to do A few more details Internals and Interims Related to grouping is the internal numeric datatype When numeric variables are defined as interim you can quickly overload them inside a group newinternal mynumber mynumber 1 begingroup interim mynumber 0 endgroup You can only interim a variable if it is already defined using newinternal Among the metarost macros is one called drawdot This macro is kind of redundant because at least at first sight you can use draw to achieve the same result There is however a very subtle difference a dot is slightly larger than a drawn point We guess that it s about the device pixel so you may not even notice it It may even be due to differences in accuracy of the methods to render them pickup pencircle scaled 50pt drawdot origin shifted 120pt 0 draw origin shifted 60pt 0 drawdot origin draw origin withcolor white setbounds currentpicture to boundingbox currentpicture enlarged ipt content index reference Embedded gr
346. untering messages with regards to redundant expressions The following code is for instance a recipe for problems zi 1 0 z1 2 0 Changing the into helps but this may not be what you want Because the z variables are used frequently they are reset each figure You can also reset them yourself using the clearxy macro The METAFUN version clears all z variables unless you explictly specify what variables to reset If you want to play with this macro see what happens when you run the following code show x0 z0 10 10 show x0 x0 whatever yO whatever show x0 z0 20 20 show x0 clearxy 0 show x0 z0 30 30 So the following calls are all legal clearxy clearxy 1 clearxy 1 8 10 Keep in mind that for each figure a full clear is done anyway You should not confuse this command with clearit which clears currentpicture This version resulted from a discussion on the METAFONT discussion list and is due to Bogustaw Jackowski A few more details Page 197 TEX versus METAPOST TEX versus METAPOST If you are defining your own Tpx and meTaPosT macros you will notice that there are a couple of essential differences between the two macro languages In Tx the following code is invalid def fancyplied 1 ifnum 1 0 message zero argument fi count0 1 multiply countO by count0 count2 1 multiply count2 by 2 count4 1 divide count4 by 2 advance coun
347. ure mycow pdf scaled 3cm metafun macro addbackeground text addbackground withcolor 625 yellow metafun macro image text draw image draw fullcircle xscaled 4cm yscaled 1cm metapost macro content index reference Literature There is undoubtly more literature about metaPost and the tools described in this document than is mentioned below More information on TeX METAFONT and METAPOST can be found at the internet sites of the local TeX user groups D 1 METAFONT and METAPOST When this document was written METAPOST was not used that widely Nowadays it is the natural companion to TeX and more macros have been written The next list reflects the state when we started with METAFUN and for completeness only a few entries were added When the development of metarost was transfered from the original author to a larger team the maintaince of the manual also became more dynamic The relevant documents can be found in Tpx distributions and at CTAN Knuth D E 1986 The Metafont book Reading MA Addison Wesley Hobby J D 1997 A User s Manual for Metapost Murray Hill NJ AT amp T Bell Laboratories D 2 TEX Reading the Tex book is not needed in order to work with metaPosT but it will give you a good perspective in what atmosphere it evolved content index reference Knuth D E 1986 The TeXbook Reading MA Addison Wesley CONTEXT At the time the f
348. us Icame to the conclusion that the designer of a new system must not only be the implementer and first large scale user the designer should also write the first user manual The separation of any of these four components would have hurt TEX significantly If I had not participated fully in all these activities literally hundreds of improvements would never have been made because I would never have thought of them or perceived why they were important Buta system cannot be successful ifitis too strongly influenced by a single person Once the initial design is complete and fairly robust the real test begins as people with many different viewpoints undertake their own experiments Douglas R Hostadter Donald Knuth has spent the past several years working on a system allowing him to control many aspects of the design of his forthcoming books from the typesetting and layout down to the very shapes of the letters Seldom has an author had anything remotely like this power to control the final appearance of his or her work Knuth s TEX typesetting system has become well known and available in many countries around the world By contrast his METAFONT system for designing families of typefaces has not become as well known or available In his article The Concept of a Meta Font Knuth sets forth for the first time the underlying philosophy of METAFONT as well as some of its products Not only is the concept exiting and clearly well executed bu
349. ut these variables the assignment would have been rot i pos i 5wid i len n 180 Placing the pictures is now rather easy startMPdrawing for i 1 upto n draw pic i shifted radius 0 rotatedaround origin rot i endfor stopMPdrawing The pictures are now positioned on half a circle properly kerned A bit more insight is given in the next picture Typesetting in METAPOST This was defined as follows The path variable tcycle is predefined to the top half of a fullcircle startMPdrawing def moved expr i shifted radius 0 rotatedaround origin rot i enddef pickup pencircle scaled 5pt for i 1 upton draw pic i moved i draw boundingbox pic i moved i withcolor red draw origin center pic i moved i withcolor green endfor draw tcircle scaled 2r withcolor blue stopMPdrawing We will now package all of this into a nice efficient macro using of course the predefined scratch registers MPtoks and MPbox First we define the token processor Note again the expansion inhibition switch content index reference def processrotationtoken 1 appendtoks 1 to MPtoks setbox MPbox hbox RotFont the MPtoks startMPdrawing n n 1 len n the wd MPbox stopMPdrawing startMPdrawing pic n textext RotFont setstrut strut 1 pic n pic n shifted llcorner pic n stopMPdrawing The main macro is a bit more complicated but by using a fe
350. w scratch numerics we can keep it readable def rotatetokens 1 2 3 4 delta extra radius tokens vbox bgroup MPtoks emptytoks resetMPdrawing startMPdrawing picture pic numeric wid len rot numeric delta extra radius n r len 0 n 0 delta 1 extra 2 radius 3 stopMPdrawing handletokens 4 with processrotationtoken startMPdrawing Typesetting in METAPOST r len n Pi for i 1 upto n wid abs xpart lrcorner pic i xpart llcorner pic il rot extra delta len i 5wid len n 180 2delta draw pic i rotatedaround origin 270 shifted r radius ypart 5 ulcorner pic i llcorner pic i rotatedaround origin rot endfor stopMPdrawing MPdrawingdonetrue getMPdrawing resetMPdrawing egroup We can use this macro as follows startcombination 3 1 rotatetokens 0 0 0 Does it work ok A rotatetokens 20 0 0 Does it work ok B rotatetokens 20 30 0 Does it work ok C stopcombination Typesetting in METAPOST Page 409 TEX text The previous macro is not really an example of generalization but we used it for demonstrating how to build graphics in a stepwise way If you put the steps in buffers you can even combine steps and replace them at will This is how we made the previous step by step examples We put each sub graphic in a buffer and then called the ones we wanted We now present a more general approach to
351. w some arb N core Me we startuseMPgraphic followtokens grap path RotPath RotPath 3cm 0 1cm 1cm Ocm 2cm 3cm 0 stopuseMPgraphic Typesetting in METAPOST Page 413 TEX text Page 414 TpxX text 2 2 bityat bityat When turned on tracing will produce bounding boxes as well as draw the path Tracing can be turned on by saying startMPinclusions boolean TraceRot TraceRot true stopMPinclusions The next example is dedicated to Giuseppe Bilotta who wants to handle multiple strings and uses a patched version of followtokens To avoid a complicated explanation we will present an alternative here that uses overlays This method also avoids complicated path definitions startoverlay startuseMPgraphic followtokens draw fullcircle scaled 5cm withpen pencircle scaled ipt withcolor 625yellow Typesetting in METAPOST draw fullsquare scaled 5 25cm withpen pencircle scaled ipt withcolor 625red drawoptions withcolor 625red path RotPath RotPath halfcircle scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens Met a superiore startuseMPgraphic followtokens drawoptions withcolor 625red path RotPath RotPath halfcircle rotated 90 scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens star startuseMPgraphic followtokens dra
352. w this line startuseMPgraphic text cutoff path tt bb tt ulcorner q urcorner q shifted 0 topskip bb llcorner q lrcorner q shifted 0 strutdepth 1 cutbefore 1 intersectionpoint tt l cutafter l intersectionpoint bb r cutbefore r intersectionpoint bb Typesetting in METAPOST Page 425 Talking to Tex r r cutafter r intersectionpoint tt stopuseMPgraphic Because we use includeMPgraphic to construct the graphic we can redefine text draw to show the result of this effort startuseMPgraphic text draw drawarrow p withpen pencircle scaled ipt withcolor red drawarrow 1 withpen pencircle scaled 1pt withcolor green drawarrow r withpen pencircle scaled ipt withcolor blue stopuseMPgraphic The text graphic now becomes startuseMPgraphic text includeMPgraphic text path includeMPgraphic text vars includeMPgraphic text move includeMPgraphic text split includeMPgraphic text cutoff includeMPgraphic text draw stopuseMPgraphic Or as graphic Typesetting in METAPOST Page 426 Talking to Tex We are now ready for an attempt to calculate the shape of the text For each line we have to calculate the left and right intersection points and since a line has a height and depth we have to determine which part touches first startuseMPgraphic text calc vardef found_point expr lin pat sig pair a b a pat intersection_point lin shifted 0 strutheight
353. was defined as defineframed Shaped background Shape frame off location low Positional graphics Page 265 More layers Watch how the graphics are moved to the background while the frame of the first text stays on top since it remains part of the text flow some text with a frame some text with a frame In the previous instance of the example we have reversed the stacking Reversal can be done with the direction directive setuplayer BackLayer direction reverse You can influence the placement of a background component by using a different anchor point setuplayer BackLayer position no corner bottom height paperheight setlayer BackLayer x 1cm y 10cm location b1 externalfigure somecow pdf width 1cm setlayer BackLayer x 5cm y 8cm location br externalfigure somecow pdf width 1cm set layer BackLayer x 1cm y 4cm location t1 externalfigure somecow pdf width 1cm setlayer BackLayer x 10cm y 5cm location tr externalfigure somecow pdf width 3cm Instead of using relative positions you can also use absolute ones Of course you need to know how your coordinates relate to the rest of the layout definition setuplayer BackLayer position no corner bottom height paperheight setlayer BackLayer x 15cm y 5cm location b1 externalfigure somecow pdf width 3cm setlayer BackLayer
354. what CONTEXT can do for you we recommend the beginners manual and the reference manual as well as the wiki pages External graphics Since Tx has no graphic capabilities built in a graphic is referred to as an external figure A METAPOST graphic often has a number as suffix so embedding such a graphic is done by externalfigure graphic 123 width 4cm An alternative method is to separate the definition from the inclusion An example of a definition is useexternalfigure pentastar star 803 height 4cm useexternalfigure octostar star 804 pentastar Embedded graphics Page 202 External graphics Here the second definition inherits the characteristics from the first one These graphics can be summoned like placefigure A fivel lpoint star drawn by METAPOST externalfigure pentastar Here the stars are defined as stand alone graphics in a file called star mp Such a file can look like def star expr size n pos for a 0 step 360 n until round 360 1 1 n draw origin size 2 0 rotatedaround origin a shifted pos endfor enddef beginfig 803 pickup pencircle scaled 2mm star 2cm 5 origin endfig beginfig 804 pickup pencircle scaled imm star icm 8 origin pickup pencircle scaled 2mm star 2cm 7 3cm 0 endfig end Embedded graphics Page 203 Integrated graphics This star macro will produce graphics like X KK k But now that we have instant me
355. when the layer is flushed its content is gone You can take advantage of this by using the same graphic with multiple texts definelayer test You don t need to pass the width and height explicitly but when you do so you have access to them later Positional graphics startuseMPgraphic oeps path p p fullcircle scaled 6cm fill p withcolor 8white draw p withpen pencircle scaled 1mm withcolor 625red register somepos 1 0cm 0cm center currentpicture register somepos 2 3cm 1icm 1cm 1cm register somepos 3 2cm 0cm 2cm 2cm stopuseMPgraphic The METAFUN register macro takes the following arguments register tag width height x offset y offset The width and height are available in the macros MPlayerwidth and MPlayerheight and are equivalent to MPw tag and MPh tag setMPlayer test somepos 1 location c Does it work al right setMPlayer test somepos 2 framed width MPlayerwidth height MPlayerheight background color backgroundcolor white It Works setMPlayer test somepos 3 externalfigure cow mps width 2cm Positional graphics Page 272 Complex text in graphics Combining the graphic and the text is handled by the macro getMPlayer getMPlayer test useMPgraphic oeps Does it work al right It Works The macro getMPlayer is built on top of framed The settings passed in the optional second argument are t
356. withcolor cyan drawarrow centerarrow p 90 3cm withcolor magenta Current picture When you draw paths texts and or pictures they are added to the so called current picture You can manip ulate this current picture as is demonstrated in this manual Let s show a few current picture related tricks draw fullcircle scaled 1cm withpen pencircle scaled 1mm withcolor 625red O We can manipulate the picture as a whole draw fullcircle scaled 1cm withpen pencircle scaled 1mm withcolor 625red currentpicture currentpicture slanted 5 O Sometimes it s handy to temporarily set aside the current picture Welcome to MetaPost draw fullcircle scaled 1cm withpen pencircle scaled 1mm withcolor 625red currentpicture currentpicture slanted 5 pushcurrentpicture draw fullcircle scaled 1cm withpen pencircle scaled 1mm withcolor 625yellow currentpicture currentpicture slanted 5 popcurrentpicture O SF These are METAFUN commands but metarost itself comes with a variant image and you explicitly have to draw this picture or otherwise add it to the currentpicture draw fullcircle scaled 1cm withpen pencircle scaled 1mm withcolor 625red currentpicture currentpicture slanted 5 draw image draw fullcircle scaled icm withpen pencircle scaled imm withcolor 625yellow currentpicture currentpicture slanted 5 3 Each graphic starts fresh with an empty current picture In MET
357. woptions withcolor 625red path RotPath RotPath halfcircle rotated 180 scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens Met a inferiore startuseMPgraphic followtokens drawoptions withcolor 625red path RotPath RotPath halfcircle rotated 270 scaled 5cm setbounds currentpicture to boundingbox fullcircle scaled 5 25cm stopuseMPgraphic followtokens star stopoverlay Typesetting in METAPOST Page 415 TEX text In order to fool the overlay macro that each graphic has the same size we force a bounding box Talking to TEX Sometimes others may say oftentimes we are in need for some fancy typesetting If we want to typeset a paragraph of text in a non standard shape like a circle we have to fall back on parshape Unfortunately TEX is not that strong in providing the specifications of more complicated shapes unless you are willing to do some complicated arithmetic TEx Given that MeTarost knows how to deal with shapes the question is Can METAPOST be of help In the process of finding out how to deal with this we first define a simple path Because we are going to replace pieces of code we will compose the graphic from components First we create the path Typesetting in METAPOST Page 417 Talking to Tex startuseMPgraphic text path path p p 0 1 1 0 1 0 cycle scaled 65pt stopuseMPgraph
358. words are proper english we let the pictures speak for themselves currentpicture currentpicture shifted 0 1cm MetaFun currentpicture currentpicture rotated 180 RI I T currentpicture currentpicture rotatedaround origin 30 A few more details Page 166 Transformations currentpicture currentpicture scaled 1 75 MetaFun currentpicture currentpicture scaled 1 H4 I Ni currentpicture currentpicture xscaled 3 50 TAA c to Fas currentpicture currentpicture xscaled 1 nuela Mi currentpicture currentpicture yscaled 5 MetaFun currentpicture currentpicture yscaled 1 NGS ENY A few more details Page 167 Transformations currentpicture currentpicture slanted 5 Metafun currentpicture currentpicture slanted 5 currentpicture currentpicture zscaled 75 25 pues currentpicture currentpicture reflectedabout llcorner currentpicture urcorner currentpicture gree Y oe A path has a certain direction When the turningnumber of a path is larger than zero it runs in clockwise direction The mMetarost primitive reverse changes the direction while the macro counterclockwise can be used to get a path running in a well defined direction A few more details Page 168 Only this far drawoptions withpen pencircle scaled 2pt withcolor 625red path p p fullcircle scaled icm drawarrow p
359. wpoints p The smoothed operation is a less subtle one since it operates on the bounding box and thereby can result in a different shape path p p 1 0 2 0 2 2 cycle xysized 4cm 2cm drawpath p drawpoints p p p shifted 5cm 0 smoothed 5cm drawpath p drawpoints p content index reference Page 93 Some extensions The next one simplified can be applied to paths that are constructed automatically Instead of testing for duplicate points during construction you can clean up the path afterwards path p p CCOR OES Gl 0E EE ERA DE 20y le xysized 4cm 2cm drawpath p drawpoints p p simplified p shifted 5cm 0 drawpath p drawpoints p A cousin of the previous operation is unspiked This one removes ugly left overs It works well for the average case Welcome to MetaPost Page 94 Some extensions path p p CORIO at E T E E O cyicilicy xysized 4cm 2cm drawpath p drawpoints p p unspiked p shifted 5cm 0 drawpath p drawpoints p There are a couple of operations that manipulate the path in more drastic ways Take randomized path p p fullsquare scaled 2cm drawpath p drawpoints p p p shifted 5cm 0 randomized 5cm drawpath p drawpoints p Welcome to MetaPost Page 95 Some extensions Or how about squeezed path p p fullsquare scaled 2cm randomized 5cm drawpath p drawpoints p p p shifted 5
360. x 5 x 4 w 4 5u y 5 y 4 h 4 5u Because we are going to repeat ourselves we draw the areas using a macro Depending on its importance we color it red or yellow def do_it expr xx yy cc draw unitsquare xyscaled wlxx hlyy shifted x xx yLyy withcolor if cc 625red else 625yellow fi enddef fill unitsquare xyscaled width height withcolor 85white do_it 1 1 false do_it 5 1 false do_it 2 1 false do_it 3 1 false do_it 4 1 false do_it 1 2 false do_it 5 2 false do_it 2 2 true do_it 3 2 true do_it 4 2 true do_it 1 3 false do_it 5 3 false do_it 2 3 true do_it 3 3 true do_it 4 3 true do_it 1 4 false do_it 5 4 false do_it 2 4 true do_it 3 4 true do_it 4 4 true Page backgrounds Page 281 The basic layout do_it 1 5 false do_it 5 5 false do_it 2 5 false do_it 3 5 false do_it 4 5 false This picture in itself is not yet explanatory so we add some labels Again we use a macro which we feed with a picture generated by Tpx Since these pictures are filtered from the source and pre processed we cannot embed the btex etex in the macro do_it and pass a string It has to be done this way def do_it expr yy tt path p p unitsquare xyscaled w 1 hlyy shifted x 1 ylyy label 1ft tt center p shifted w 1 2 u 25cm 0 enddef do_it 1 btex bottom etex do_it 2 btex footer etex
361. xpart xypart xxpart ypart yxpart and or yypart you may as well forget about the internal representation You can invert a transformation using the inverse macro which is defined as follows using an equation vardef inverse primary T transform T_ T_ transformed T identity T_ enddef Using transform matrices makes sense when similar transformations need to be applied on many paths pic tures pens or other transforms However in most cases you will use the predefined commands scaled shifted rotated and alike We will now demonstrate the most common transformations in a text example draw btex bfd MetaFun etex draw boundingbox currentpicture withcolor 625yellow Before a METAPOST run the btex etex s are filtered from the file and passed on to Tx After that the DVI file is converted to a list of pictures which is consulted by metarost We can manipulate these pictures like any graphic as well as draw it with draw MetaFun We show the transformations in relation to the origin and make the origin stand out a bit more by painting it a bit larger in white first 7 end as 2 This is no longer the case in LUATsX where we use MPLIB A few more details Page 165 Transformations draw origin withpen pencircle scaled 1 5mm withcolor white draw origin withpen pencircle scaled 1mm withcolor 625red The origin is in the lower left corner of the picture MetaFun Because the transformation key
362. y top y6 path r r 1x ly ux ly ux uy 1x uy cycle The clipping path is applied by saying clip currentpicture to r The result is quite acceptable A few applications But if you watch closely to how this graphic extends into to left margin of this document you will see that the bounding box is not yet right setbounds currentpicture to r We use the same path r to correct the bounding box There are a few subtle points involved like setting the 1inejoin variable If we had not set it to mitered we would have got round corners We don t set the linecap because a flat cap would not extend far enough into the touching curve and would have left a small hole The next example shows what happens if we set these variables to the wrong values A few applications Page 540 Simple Logos In fact we misuse the fact that both curves overlay each other The complete logo definition is a bit more extensive because we also want to add a background Because we need to clip the blue foreground graphic we must temporarily store it when we fill the background numeric width height line delta width 5cm height width 2 line height 4 delta line linejoin mitered pickup pencircle scaled line color nsblue nsblue OOD mee color nsyellow nsyellow 1 1 0 zi 0 height 2 z2 width 2 height 4 y1 A few applications Page 541 Simple Logos z3 width 2theigh

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