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SIMSCRIPT III 3d Graphics Manual

1. Event Id Cause _activate User clicked on window Window brought to front _close User clicked on the X to close the window _key_down Pushing down a key on the keyboard _key_up Releasing a key on the keyboard _mouse_down Clicking in the canvas with the mouse _mouse_up Releasing the mouse button in the canvas _mouse_move Moving the mouse in the canvas mouse_wheel_forward Spin mouse wheel away from user forward mouse_wheel_backward Spin mouse wheel toward used backward _reposition Dragging the window with the mouse _resize Resizing the window with the mouse E Sample Window Window acl mouse_up C ane 5 Frame waa A _mouse_down indow AU AWALANT mouse move Canvas 4 a resize Figure 20 Event ids of a 3dwindow object handled by the action method The action method should return one of the following two predefined contants _continue or _block If _continue is returned the runtime library will handle the event Returning with _block means that the runtime library will take no action in response to the event For example to keep the window from disappearing when closed by the user the overridden action method should return with _block instead of _continue In the following example the action method is overridden to respond to the user pressing the arrow keys 123 Method action event If id event 3devent _key_down Select case key_co
2. oe 2u 0o o t world now activate a animate window 30 now 73 end Example 6 Showing a 2d image using texture mapping n fon Es EVER VIGILANT Figure 7 5 Example 6 A texture mapped cube 74 8 User Input One of the advantages of a graphical simulation is the ability to interact with elements as the simulation runs SIMSCRIPT 3d graphics provides allows the user to interact with the mouse keyboard graphics window frame and objects inside the window 8 1 Mouse keyboard and window frame interaction In a SIMSCRIPT 3d program the active or top 3d window can be thought to receive events from the mouse keyboard as well as the moving or resizing of the window frame In order to receive mouse keyboard or window events the program must subclass the 3dwindow can override its action method This method is called automatically in response to a user driven event Another object found in 3d m called 3devent is used by the action method This object contains all data relevant event data An instance is created by the runtime library and passed as the argument to the action method The id attribute of 3devent is set to one of several predefined constants and describes the event that occurred The list of possible events id constants is shown below Id event Cause 3devent attributes activate User clicked on window Window brought to front close User clicked
3. points 18 points 10 points 11 points 12 points 13 points 14 points 15 points 16 points 17 points 18 lig tiyg tga Ny htys igs ling ty6 tiz yd igg ig4 Hy ngs 1izZ5 1i 1146 ig6 eee Gy a a ee points l xl points 2 yl points 3 zl points 4 x2 points 5 y2 points 6 z2 points 7 x3 points 8 y3 points 9 z3 Each successive point defines a new triangle using the first center point Figure 3 the 3dgraphic _triangle_fan format points 1l xl points 2 yl points 3 zl points 4 x2 points 5 y2 points 6 z2 points x3 points 8 y3 points 9 z3 points 1l x4 points 10 y4 points 12 z4 points 16 x6 points 17 y6 points 18 z6 points 13 x5 points 14 y5 points 15 z5 points 10 x4 points 1ll y4 points 12 z4 Counter clockwise rotation normals face out points 22 x8 points 23 y points 24 z8 points 19 x7 points 20 y7 points 21 z points 16 x6 points 17 y6 points 18 z6 points 13 x5 points 14 y5 points 15 2z5 Figure 4 3dgraphic _quads format 99 Each 2 successive points adds a new face points 7 x3 points 13 xs i LE points 8 y3 points 14 y5 points 9 z3 points 15 z5 points 1 xl points 19 x points 2 y
4. let timescale v 100 set the speed of the animation start simulation 91 A A Simulation and 3d graphics Flash was clicked on Figure 9 1 Example 13 output planes circling in the sky 92 10 3d Class reference 3dbox lineage 3dbox gt 3dshape gt 3dgraphic gt 3dnode A 3dBox is used to implement a simple box with width height and depth The set_size method can be called to set these parameters If an instances material attribute is set it will apply to all sides However by using the materials array attribute each side can have its own distinct color and texture This array is reserved and destroyed automatically and its elements can be indexed using the following constants defined by 3dBox define _front 1 _back _left _right _top _bottom as constants The inherited attribute 3dshape inside_lighting attribute should be set to 1 if the viewer is intended to be inside the box This allowed effects such as a sky and ground to be implemented 3dcamera lineage 3dcamera gt 3dnode A 3dcamera is used show a view of the 3dworld on the canvas of a window For each 3d m application at least one camera must be created oriented and filed in the camera_set owned by the 3dworld otherwise nothing will be seen Since the 3dcamera object is derived from 3dnode it inherits the set_location set_orientation and set_forward methods All can be used to position and orient the camera m
5. 2 0 call set_orientation camera 0 0 0 0 1 0 0 0 1 0 0 0 file this camera in camera_set world create materials create fb_material lr_material tbh material let texture_name fb_material cacilogo bmp let texture_name lr_material agle bmp let ambient_color tb_material color rgb 0 2 0 4 1 0 let diffuse_color tb_material color rgb 1 0 0 6 1 0 let ambient_color lr_material color rgb 1 0 1 0 1 0 let diffuse_color lr_material color rgb 1 0 1 0 1 0 let visibility fb_material 3dmaterial _front let visibility lr_material 3dmaterial _front let visibility tb_material 3dmaterial _front file this fb_material file this lr_material file this tbh_material create box create box let materials let materials let materials let materials let materials let materials let width box let height box let depth box box box box box box box 0 4 0 1 0 3dbox front 3dbox _back 3dbox _right 3dbox _left 3dbox _top 3dbox _ bottom in material_set world in material_set world in material_set world fb_material fb_material lr_material lr_material tb_material tb_material file this box in motion_set file this box in node_set world create the light create light let location_z light let location_y light file this light in light_s call display window activate a spin box let timescale v 100 start simulation
6. 2 integer arguments width height pixels 1 integer argument l gt size viewport to window canvas The dimensions of the view are given in pixels with 0 0 located at the lower left corner of the window canvas see Figure 3 4 Having viewports enables the use of multiple camera objects The view from each camera can be mapped into a separate area of the canvas _ set_viewport x y w h 1 3dwindow view as seen by the 3dcamera Figure 3 4 Using the set_viewport method Since the viewport dimensions are specified in pixels in order to know what the width and height parameter values to set_viewport should be we usually need to know the 26 dimensions of the window canvas This can be obtained by reading the canvas_width and canvas_height attributes of the 3dwindow class Unfortunately these values are not updated until the window becomes visible Therefore the window must be displayed before the viewports are initialized The last parameter to the set_viewport method is a flag to indicate if the viewport dimensions should be automatically adjusted as the window is resized The viewports are modified so that they occupy the same percentage of window space after the resize operation As such if zero is passed for this flag and the user resizes the window to make it very small part of the viewport may disappear Suppose that we want to modify Example 2 to show the view from multiple camera objects We will create a second cam
7. Define the_model as a 3dmodel reference variable Create tankl tank2 the _model File the_model in model_set the_world File tankl in node_set the_world File tank2 in node_set the_world Call read the_model tank 3ds Call load tank1 the_model Call load tank2 the_model 38 3dworld node set tanki tank2 node_set node_set 3dnode turreti 3dnode turret1 3dnode 3dnode Figure 5 2 Calling the load method instead of assigning the model attribute 5 5 Locating named sub components Models may be designed in the 3d editor to have well defined components In the previous example the tank model has a component that was named turret1 in the editor for the purpose of being rotated indepedantly with respect to the tank The turret sub component may in turn have a gun sub component The application may need access to these sub components at runtime i e rotate the turret move the gun in and out when it fires etc If sub components like this are defined in the graphics editor they will be preserved when model is loaded in the application The node_set owned by the 3dmodel will contain these components Both the 3dnode and 3dmodel classes define a find method that can be called to perform a depth first search for a sub component provided that the component has been given a name in the graphics editor Let turret tankl find tankl1 turret1 Let turret
8. and override the draw method The spiral shape will be drawn by moving in a circle with a changing radius In the code to draw the spiral we place calls to the 3dgraphic class method draw_vertex in between calls to begin_drawing and end_drawing Example 9 a spiral preamble including the gui m 3d m subsystems begin class spiral every spiral is a 3dgraphic and overrides the draw end end 60 method spiral draw call set_pen_size 6 call begin_drawing 3dgraphic _points define i num_points as integer variable create geometry for spiral let num_points 2 0 pi c 3 0 0 1 create spiral points for i 1 to num_points do call set_color _front_and_back ambient color rgb 1 0 abs f sin f 0 1 i abs f cos f 0 1 i call draw_vertex 0 5 sin f 0 1 i 0 005 i 0 5 cos 0 1 i loop call end_drawing end main define window as a 3dwindow reference variable define world as a 3dworld reference variable define spiral_graphic as a spiral reference variable define camera as a 3dcamera reference variable create the window create window let title window Example 9 A spiral of points create the world create world let ambient_color world Color _white needed no light sources file this world in world_set window create the spiral and save it in the scene create spiral_graphic file this spiral_graphic in node_set world move the spiral call set_location spiral_gra
9. define set_perspective as a method given 1 double argument perspective_angle gt 0 0 lt 180 0 degrees 1 double argument perspective_ratio 2 double arguments perspective_near perspective_far 1 integer argument perspective_autosize perspective_ratio w h perspective_angle perspective_near perspective_far Figure 3 2 Using the set_perspective method The perspective_angle parameter is specified in degrees and represents that angle of the field of view in the y direction see figure 3 2 The perspective_ratio is the ratio of the width of the viewing plane to its height Values below 1 0 will cause the image to appear compressed vertically perspective_ratio values greater than 1 will compress the view horizontally However if the perspective_autosize parameter is 1 the perspective ratio will be determined based on window canvas size In this case the perspective_ratio argument will be ignored Basically turning on the perspective_autosize will avoid compressing the scene either vertically or horizontally regardless of how the user sizes the window For setting up the camera in Example 2 a perspective angle of 90 degrees is a good start The camera is located at z 60 with the nearest edge of the parking lot at z 50 meters A near clipping plane of 5 is adequate The farthest edge of the lot is at z 50 meters a distance of 110 meters The far clipping plane of 115 will allow the entire lot a
10. located at the upper right corner See Figure 7 4 70 Texture coordinates s t Original picture Figure 7 4 Texture coordinates For texture coordinate values greater than 1 0 or less than 0 0 the mapping will be handled based on the values of the texture_wrap_s and the texture_wrap_t attributes When an attribute is set to _repeat which is the default the pixel image is repeated as s t values increase past 1 0 or decrease past 0 0 If the texture wrapping attributes are set to __clamp_to_edge the same pixel values found at s t 1 0 will be copied for all values of s t gt 1 0 Pixel values found at s t 0 0 will be repeated for s t lt 0 0 Texture coordinates can only be specified when using objects derived from the 3dgraphic class The 3dgraphic draw_texture_coordinate method assigns a texture coordinate to the last vertex drawn with a draw_vertex method call The 3dfaces class allows texture coordinates to be specified in an array These are described in the next chapter 7 3 Front and back side visibility In some cases it is necessary to specify which sides of a surface can be made visible If the front or back side is always hidden some performance improvement can be made by marking that side as such The visibility attribute of 3dMaterial controls which sides are visible an invisible side will appear translucent when facing the 3dcamera One of the constants 3dmaterial _front 3dmaterial _back
11. window 10000 now start simulation 9 2 Time scaling When a typical non graphical SIMSCRIPT III simulation runs TIME V is automatically set to the time of the next pending process notice on the event set If that process notices is scheduled to run 1000 units in the future TIME V will jump ahead to that time value The behavior is not good for a graphical simulation because if time is not advancing smoothly dynamic objects will jump around without regard to the speed at which they are supposed to move For this reason SIMSCRIPT provides a global variable called TIMESCALE V TIMESCALE V is the number of 1 100ths of a second of real time per unit of simulation time Setting TIMESCALE V to 100 means that every unit of simulation time will elapse 1 second of real time Therefore assigning a low 84 value to TIMESCALE V will speed up the motion of all moving objects Its use in 3d graphics is identical the usage in 2d graphics By default TIMESCALE V is zero meaning that no time scaling is performed and TIME V will advance without delay to the time of the next event Every graphical simulation should assign this variable I want to burn 2 real seconds for every UNIT of simtime let timescale v 200 9 3 Automatic motion and the motion_set In a 3d graphics program attributes of a 3dnode object are assigned but the update of its image is automatic as long as the 3dnode instance is filed into a node_set For example s
12. yl r z loop call end_drawing loop end main define window as a 3dwindow reference variable define world as a 3dworld reference variable define camera as a 3dcamera reference variable define light as a 3dlight reference variable define torus as a torus reference variable create the window create window let title window Example 8 A soda can torus create the world create world file this world in world_set window create a camera 3 units out pointed at the origin create camera call set_perspective camera 60 0 1 0 0 1 100 0 1 call set_forward camera 0 0 0 0 1 0 call set_location camera 0 0 0 0 3 0 file this camera in camera_set world create our torus and set its size and detail parameters create a torus let minorRadius torus 3 let majorRadius torus 7 let numMinor torus 37 let numMajor torus 61 create a red material for torus s surface create a material torus let ambient_color material torus let diffuse_color material torus color white let specular_color material torus color _white let shininess material torus 1 0 let texture_name material torus cocacola bmp file this material torus in material_set world coler rgb 0 2 Oray 0 2 save the torus in the world file this torus in node_set world create a light from above set its color create light let diffuse_color light color rgb 0 8 0 8 0 c
13. 1 n n 2 in counter clockwise order polygon The outline of the polygon is defined by vertices Again the vertices for front facing polygons should be arranged in a counter clockwise order 6 2 Surface geometry The surface of a shape in 3d is composed of small by planar faces that are interconnected Round shapes that have smaller but more numerous faces will appear more detailed but could take longer to render Calls to the draw_vertex are placed inside a drawing block with the x y z values passed as arguments Each call adds a new coordinate to the shape A normal vector is perpendicular to the surface that is being drawn If a normal vector is known it can be specified by calling draw_normal The normal vector specified will apply to subsequent vertices defined by draw_vertex 46 Figure 6 1 Normal vectors To construct a 2d surface one of the following predefined constants must be passed to begin_drawing _triangles _triangle_strip _triangle_fan _quads or _polygon Using the _triangles format will draw a separate triangle for each successive group of three vertices As arule of thumb the vertices should be given in a counter clockwise ordering if the normal vector points outward Counter clockwise rotation normals face out dr t 4 y4 z drav_vertex x1 y1 z1 av_vertex x4 y4 z4 draw vertex x5 y5 z5 draw vertex x2 y2 z2 drav_vertex x3 y3 z3 drav_vertex x 6 y6 z6 Figure
14. 10 riy points 11 ney points 12 hy points 16 lity points 17 hz2 points 18 RS points 13 Vtg points 14 Pe points 15 Figure 10 3dgraphic _line_loop format 107 iyg iva igg iys Miy5 igs 1i Iy 1iz6 lig y4 tga ee 1i wt y6 iz LEs iys wt y5 tgs es Viydg y4 tig slain 1i y6 Iz 6 E 1i 5 i y5 Iz5 a Other attributes of the 3dLines object include the color width and pattern The color can be obtained from the gui m color class and applies to ambient diffuse and specular colors Line width is specified in pixels The line pattern refers to the dash style found in the 3dgraphic class and must be one of the following define _solid 0 long_dash _dotted _dash_dotted _medium_dash dash_dot_dotted _short_dash _alternate as constants In most cases the 3dlines object will be used for illustration purposes and the application will not want it to be shaded If this is the case the 3dnode enabled _lighting can be assigned to 0 This will cause the lines to be shown regardless of how lights are positioned 3dmaterial The 3dmaterial object defines the skin of the object being drawn It is not derived from 3dnode but instead can be set as the current drawing material for the 3dgraphic draw method Objects derived from 3dshape also have a material attribute that can be assigne
15. 6 2 _triangles format The __triangle_strip format is sometime referred to as a triangular mesh or just mesh It can be used to construct surfaces composed of interconnected triangles Each call to draw_vertex will add a new triangle to the shape using the two previous coordinates given by draw_vertex 47 Each successive point defines a new triangle draw vertex x4 y4 z4 draw_vertex x5 y5 z5 a raw_vertex x1 y1 z1 Graw_vertex x2 y2 zZ2 draw vertex x3 y3 z3 draw vertex x6 y6 z6 Figure 6 3 _triangle_strip format When using the _triangle_fan format draw_vertex will add a new triangle using the first vertex and the previous vertex This format can be useful for drawing circular shapes Each successive point defines a new triangle using the first center point araw_vertex x1 y1 z1 araw_vertex x6 y6 z6 araw_vertex x2 y2 z2 arav_vertex x5 y5 z5 draw_vertex x3 y3 z3 av_vertex x4 y4 z4 Figure 6 4 Triangle fan Surfaces composed of quads or 4 point planar regions can be defined When using the _quads format each group of 4 vertices defines a new quadrilateral face 48 Counter clockwise rotation normals face out drav_vertex x8 y z amp draw_vertex x7 y7 z7 araw_vertex x1 y1 z1 araw_vertex x2 y2 z2 drav_vertex x3 y3 z3 draw_vertex x6 y6 z6 draw_vertex x4 y4 z4 draw_vertex x5 y5 z5 Figure 6 5 _quads format Much like the trian
16. In turn the 3dworld class owns the following sets camera_set The purpose of the 3dcamera class is to show the 3dnode objects contained in the world Each camera will only see objects that are attached to the same world In order for the view seen by a 3dcamera to be visible the 3dcamera must be filed in a camera_set A 3dcamera instance can optionally be filed in a node_set light_set 124 3dlight instances must be filed into the light_set before use A 3dlight instance will only illuminate the 3dworld owning the light_set that it is filed in A 3dlight instance can also be filed in a node_set if it is to be attached to a visible object material_set 3dmaterial instances may be used to define the surface characteristics of a 3dfaces or 3dgraphic instance They must be filed in the material_set owned by the world in which they are used or alternatively in the 3dmodel material_set the 3dmodel owner must be filed in the same 3dworld model_set model_set A 3dmodel must be filed in the model_set owned by a 3dworld before the 3dnode object s that reference it are displayed Each 3dmodel object instance may be referenced by many 3dnode instances but both the 3dmodel and the 3dnode instances must belong to sets owned by the same 3dworld node_set The node_set contains all objects derived from 3dnode that can be positioned oriented and viewed The hierarchical usage of the 3dworld node_set is how the scene graph is defined
17. Note that 3dcamera and 3dlight instances can optionally be filed in the node_set since they are derived from 3dnode This could be used to implement the view seen from a moving object a mobile light source etc The ambient_color attribute controls the color and intensity of ambient light throughout the 3dworld The intensity of the ambient light can be adjusted by using darker colors For example setting ambient_color to gui m color rgb 0 2 0 2 0 2 will result in less ambient light Picking or selection is supported through the 3dworld The select_node method can be used to locate the visible node at a given pixel location in the window s canvas The select_node method returns the leaf node under the x y pixel location given in the first 2 arguments If overlapping nodes are selected the node closest to the camera is returned 0 is returned if no node is selected by x y define select_node as a 3dnode reference method given 2 integer arguments pixel x y location The easiest way to use the select_node method is from within the action method of the 3dwindow class In the following code the 3dwindow action method is overridden to receive mouse clicks The click location is used to pick a node by calling select_node for each world in the world_set Method my_window action event define node as a 3dnode reference variable define world as a 3dworld reference variable respond to the _mouse_down eve
18. To support this the 3dwindow is sub classed and its action method overridden The _mouse_down event is handled as shown above The select_node method owned by the 3dworld class can then be called to determine which node was clicked on Select_node takes the location in pixels of the mouse click and returns with the selected leaf node in the scene graph The location in pixels can be obtained from the x and y attributes of the 3devent instance argument to action The select_node method will always return the leaf node in the scene graph that was selected Many times the leaf node will compose low level geometry that is not interesting to the application The get_owner_node method of this leaf can be called to get the node that contains it in its node_set 80 In the following example10 will be modified to allow the user to click on the people model that is displayed In the particular model the people are represented by a scene graph of body parts like chest head and abdomen etc Our example will print the name of the body part that was clicked Since the select_node method returns with a node in the visible scene graph it is important to note that the 3dmodel in this example must be loaded by calling the 3dnode load method instead of begin simply referenced by assigning the model attribute Otherwise there would only be one node in the visible scene graph and that same node would be returned regardless
19. a 3dcamera reference variable define the_message as a 3dtext reference variable define _max_elevation 2000 0 as a constant end helper method to draw a single triangle method moving_jet draw_triangle plx ply plz p2x p2y p2z p3x p3y p3z define nx ny nz as double variables call 3d m compute_normal_vector plx ply plz p2x p2y p2z p3x p3y p3z yielding nx ny nz call draw_normal nx ny nz 88 call draw_vertex plx ply piz call draw_vertex p2x p2y p2z call draw_vertex p3x p3y p3z end The method is called by the system whenever it needs to know how to draw the jet code is provided to construct the geometry method moving_jet draw call set_color _front _ambient color call set_color _front _diffuse color call begin_drawing _triangles call draw_triangle 0 0 0 0 60 0 15 0 0 0 30 0 15 0 0 0 30 0 call draw_triangle 15 0 0 0 30 0 0 0 15 0 30 0 0 0 0 0 60 0 call draw_triangle 0 0 0 0 60 0 0 0 15 0 30 0 15 0 0 0 30 0 call draw_triangle 15 0 0 0 30 0 0 0 15 0 30 0 0 0 0 0 56 0 call draw_triangle 0 0 0 0 56 0 0 0 15 0 30 0 15 0 0 0 30 0 call draw_triangle 15 0 0 0 30 0 15 0 0 0 30 0 0 0 0 0 56 0 call draw_triangle 0 0 2 0 27 0 60 0 2 0 8 0 60 0 2 0 8 0 call draw_triangle 60 0 2 0 8 0 0 0 7 0 8 0 0 0 2 0 27 0 call draw_triangle 60 0 2 0 8 0 60 0 2 0 8 0 0 0 7
20. a method given 1 integer boolean argument Q gt invisible 1 gt visible specifies visibility of future edges of a face 6 5 Surface texture mapping Texture mapping can be applied to surfaces created in a drawing block The draw_texture_coordinate method can be called to map the vertex specified by draw_vertex to a 2d texture coordinate texture mapping is explained in more detail later The previous example could be modified to wrap a texture over the surface of the torus The image that will be mapped is that of a soda can label saved in the file cocacola bmp The surface will be parameterized to the s t coordinate space of used for texture mapping whose domain is s gt 0 1 and t gt 0 1 0 0 is the lower left corner of the 2d image and 1 1 is the upper right corner For each call to draw_vertex a corresponding call to draw_texture_coordinate is added Also the texture_name attribute of the 3dmaterial used to set the surface color will be assigned to cocacola bmp 54 We will also modify the color of the material used for the torus The 2d image file will provide the color information and since we don t want that color to be modified _white will be used for the diffuse color and a dark gray for the ambient color The new example code is shown below with the modified and new color colored red Example 8 a texture mapped 3d torus preamble for the toruses system including the 3d m subsys
21. appear shiny 4 3 Setting up the lighting using the 3dlight To summarize setting up lighting involved the following set of steps a Create instance s of a 3dlight object b Optionally set the location the direction of the light using the set_location and set_forward methods inherited from 3dnode 34 c Set the type of light by assigning the variety attribute _positional _directional _spot d Assign the ambient_color diffuse_color and specular_color attributes in accordance with the desired properties e File the 3dlight object instance into the light_set owned by the 3dworld that will contain the light f Optionally file the light into a node_set if it is to be attached to an object in the scene graph In examples 2 and 3 above a single directional light source is used The light is pointed away from the viewer along the negative Z axis by calling the set_forward method If the light were to be directed along the positive Z axis the objects in the foreground would be back lit and difficult to see The default ambient diffuse and specular color attributes are used create a light source and point it in the same direction as the camera create light call set_forward light 0 0 0 0 1 0 file this light in light_set world We can make the lighting more interesting in this example by creating a spot variety light and automatically pointing it at the tank as it moves around For the spot light a
22. attribute shape_mode attribute Resulting shape 0 _full_mode Solid ellipse or circle This is the DEFAULT 0 _arc_mode Chord drawn from start_angle to end_angle 0 _pie_mode Solid pie slice Chord drawn from start_angle to end_anegle 0 _chord_mode Chord drawn from start_angle to end_angle 1 _full_mode Hollow ellipse or circle 1 _arc_mode Arc drawn from start_angle to end_angle 1 _pie_mode Hollow pie slice drawn from start_angle to end_angle 95 1 _chord_mode Hollowed chord drawn from start_angle to end_angle When the shape_mode attribute is not set to _full_mode The start_angle and stop_angle attributes determine the starting point and range of the pie arc or chord Each angle is measured in degrees counter clockwise from the positive local x axis Defaults values for start_angle and stop_angle are 0 and 360 respectfully The radius_x and radius_y attributes specify the major and minor axis length respectfully For a circle radius_x radius_y for an elliptical shape radius_x lt gt radius_y 3devent lineage 3devent gt gui m guievent An instance of a 3devent is passed to the 3dwindow action method when the user types on the keyboard clicks in the window with the mouse or resizes the window 3devent is derived from gui m guievent and each instance will contain attributes pertinent to the type of event button_number number of the mouse button that was pr
23. by either the 3dworld or by another 3dnode attached to a 3dworld Geometry and surface materials can be specified by sub classing 3dgraphic and overriding the draw method The draw method is called automatically when the system needs to have the 3dgraphic object rendered Calling the 3dwindow display method will invoke this method Draw may also be called as a result of event handling The draw method is programmed to make calls to begin_drawing and end_drawing class methods to define each surface After the call to begin_drawing calls to class methods such as draw_normal draw_texture_coordinate and draw_vertex allow geometry to be specified for the surface A call to end_drawing will mark the end of the geometry description started by begin_drawing define begin_drawing as a method given 1 integer argument format define end_drawing as a method The format argument to begin_drawing must be one of the following predefined constants _points Draw dots in 3d space Each call to draw_vertex adds a dot See 3dpoints class _lines Each 2 successive vertices defines a line segment see 3dlines class _line_loop Each vertex is connected to the next with the first connected to last see 3dlines class _line_strip Each vertex is connected to the next see 3dlines class _triangles Each successive group of 3 vertices defines a triangle _triangle_strip For each index n gt 2 a triangle is defined by vertex at n 2 n 1 a
24. for the aligh_horiz attribute define _bottom 0 _middle _top _bottom_cell _top_cell as constants for the align_vert attribute 64 fot le bottom Text 3 Alignment Lleft_justified _bottom _left_justified Lleft_justified _middle cleft justified middie ified _top ied _bottom_cell _left_justified _bottom _top_cell al __ centered _centered _centered middle _top centered ight justified _bottom _middle _top rig Fe justified T cell _right_justified _top_cell ttom_cell _top_cell _right_justifi ied _right_ _right_justi _midde a _top_cell _tight_justified _left_justified a cell _top_cell a _left justified 7 ai _bottom_cell bottom cell _centered _bottom_cell _centered middle Figure 6 18 3dtext alignment 6 9 Updating the graphic By default the draw method is only called once by the system when the 3dgraphic first appears If the geometry or surface has changed the update_drawing method must be called to indicate that the 3dgraphic is old and that the draw method should be invoked the draw method should never be called directly define update_drawing as a method given 1 integer argument always _once _never 65 _never Draw will not be called Graphic will effectively be hidden from view once Draw called the next time the window is refreshed The image of the 3dgraphic will be cached for future r
25. forward distance define _forward_speed 2 as a constants let speed _forward_speed wait abs f distance speed units let speed 0 0 end process method tank spin angle 41 define _spin_speed 20 as a constants let spin_rate _spin_speed sign f angle wait abs f angle _spin_speed units let spin_rate 0 end process method tank movement call forward 40 call spin 180 call forward 40 call spin 90 call forward 40 call spin 90 end process method turret spin angle define _spin_speed 10 as a constant let spin_rate _spin_speed sign f angle wait abs f angle _spin_speed units let spin_rate 0 end process method turret movement call spin 45 wait 2 0 units call spin 90 wait 1 0 units call spin 180 call spin 30 wait 1 0 units call spin 40 end our motion method will be called as simulation time advances method tank motion dt call 3dnode motion dt call rotate_y dt spin_rate call move 0 0 0 0 dt speed end method turret motion dt call rotate_y dt spin_rate end main define world as a 3dworld reference variable define camera as a 3dcamera reference variable define light as a 3dlight reference variable define tank_model as a tank_model reference variable define the_tank as a tank reference variable define the_turret as a turret reference variable define p as a pointer variable create the window create window let title window Example 5 A
26. instance to a 3dnode instance eseeeseeeseeeeesesereeresseserssresereses 37 5 4 Copying the scene graph of a 3dmodel 0 eee ceescecssececesececeeneeceeeeeceeeeeeeteeeesaes 38 5 5 Locating named sub cOMponenttS ccceesceceeseeceseeeceeececseeeecseeecseeecseeeeneeeeaees 39 5 6 Deriving from sub components cosesdyis cev escediveibeddeavevsvaessatesdaneseedscacwenscedeneesaeetcceanats 39 5 7 IVES Ce SOMOS LO LONG io conic Si woah ca asa ah Detar tet E dea was gle Dtba 43 6 ASC OMIG LEY es coacoks n a a usar eras ga dnaen is a r ona are E N 45 GL Using the Sderaphic Class c sies cagutsccrsueisocye tie bac ain a aeeaiauenceasees 45 0 2 SUITACE geometry oiiaee rea E AAE ad ee Oar et 46 GA SITET 0 0E Ce aO EE EEEE E E TT 53 6 5 Surface text re MAPPING 5 5c save ssccsaseasesceancededachersnnendtooeqasnudeledd aS EEEE OE S aeaieie 54 6 6 Drawing points and lines sssessssssesssesessseesseesseesseresseeesseetsstessersseessseeesseesseesseesset 57 67 Drawing pO S a a a E E 60 Se KED SE E E E E EE E 62 Bitmapped LOMts sescssicvesssvavscceeihes ovasdasdgvacvanpavaisassseacaacsacaegasdyesde eE rE S OTE Np eaaet 63 6 9 Updating th Sra pla Ons sa ccasseategronsesesouicatueadeneyteesadenaeon egee E E a oea USE a easi 65 6 8 Classes with retained geometry sessesessssesseessessseeesesttsseesstessresseresseeessresseesseesseee 66 7 Surfaces Textures and Materials cccccccccccccccccseesssescccccccssssssesecsccesesses
27. method that may be useful for setting the orientation of a 3dnode is the aim method Calling the aim method will set the forward direction of the node so that it points at a given location The location should be in global coordinates non local to the 3dnode The 3dworld get_location method can be used to convert a location from local to global coordinates When aim is used on a sub component the local orientation forward and up vectors of the sub component will be modified so that the sub component points with its positive z axis at the given location The aim method 16 can only be called after the 3dnode has been filed into the node_set Since the aim method uses the orientation and location of parent nodes it should be called after all the location of all parent grand parent etc nodes have been initialized make a passenger turn to look at a spot on the shoreline Call aim passenger 2 45000 20 0 20000 target_x target_y target_z 2 4 Shifting the position of a node The set_orientation and set_forward methods expect vectors that are oriented with respect to the node s owner in the scene graph or the 3dworld if the 3dnode is filed in 3dworld node_set Likewise the set_location method provides coordinates with respect to the coordinate system defined by node s owner in the scene graph However in some cases it may be easier to position the node with respect to its own coordinate system The move metho
28. move objects in a non linear fashion over time may by complex and even depend on conditions in the simulation To support this sub classes of the 3dnode class can override the motion method The motion method is called for all objects filed into the motion_set Here the programmer can add code to rotate scale or set the location of the object based on the time differential dt passed as the argument to motion Remember that the object must be filed into the motion_set and the simulation must be running before the motion method will be called To stop the object from moving it should be removed from the motion_set The code below was taken from example13 sim and shows the implementation of the motion method The dt argument is used in conjunction with application defined attributes such as airspeed and radius to determine the next location and orientation method moving_jet motion dt add arcsin f min f pi c 2 0 airspeed dt flight_radius to flight_angle add vertical_airspeed dt to elevation if elevation gt _max_elevation or elevation lt 0 0 let vertical_airspeed vertical_airspeed always call set_location flight_radius cos f flight_angle elevation d flight_radius sin f flight_angle call set_forward cos f flight_angle pi c 2 0 0 0 sin f flight_angletpi c 2 0 end The complete example shown below will display 10 circling planes Each plane moves in a slightly different manner at a different speed The
29. new class called tank_spotter is derived from 3dlight To achieve the automated tracking the motion method is overridden This method is described later it is called automatically as simulation time is updated The code to declare the subclass of 3dlight is begin class tank_spotter every tank_spotter is a 3dlight and overrides the motion end The implementation code for motion is method tank_spotter motion dt point the light at the tank call aim location_x the_tank location_y the_tank location_z the_tank end To initialize the light its variety attribute is assigned to spot and we must provide its location Also since a spot light is being used we should define the spot_cutoff attribute it will be set to 15 degrees Lastly in order for the light s motion method to be called automatically it must be filed into the motion_set described later create the tank_spotter light and position it near the camera create light let variety light 3dlight _spot let spot_cutoff light 15 degrees defines the light cone call set_location light 0 0 6 0 60 0 file this light in light_set world file this light in motion_set 35 Example 4 using a spot variety light E x Figure 4 4 Using a spot light to track the tank 36 5 Loading graphics files via Models 3d dimensional objects are easily maneuvered using the SIMSCRIPT 3d graphics functionality but creating three dimentional cars tank
30. of where the user clicks example 11 Selecting a 3d object preamble including the 3d m subsystems begin class my_window every my_window is a 3dwindow and overrides the action end define the_message as a 3dtext reference variable define the_world as a 3dworld reference variable end method my_window action event define node as a 3dnode reference variable tlook for a mouse down event if id event 3devent _mouse_down get which node in the scene graph was selected If it is an unnamed leaf check its owner node for a name let node select_node the_world x event y event while node lt gt 0 and name node let node get_owner_node node found a named node set the 3dtext string to its name if node lt gt 0 let string the_message Selected node named name node call update_drawing the_message 3dgraphic _once always always return with _continue tell SIMSCRIPT to do default handling for the rest of the events end main define window as a my_window reference variable define light as a 3dlight reference variable define model as a 3dmodel reference variable define the_people as a 3dnode reference variable define the_camera as a 3dcamera reference variable Create windows worlds and groups create window let title window Test of 3d component selection create the_world file this the_world in world_set window create camera s create the_ca
31. on the X to close the window key_down Pushing down a key on the key_code keyboard key_up Releasing a key on the keyboard mouse_down Clicking in the canvas with the mouse mouse_up Releasing the mouse button in the canvas mouse_move Moving the mouse in the canvas mouse_wheel forward Spin mouse wheel away from user forward mouse_wheel backward Spin mouse wheel toward used backward _reposition Dragging the window with the mouse _resize Resizing the window with the mouse 75 _repgsition AS E Sample Window Window Frame acl _mouse_up Window Ao _mouse_down Canvas _mouse_move EE WALANT 4 resize Figure 8 1 Event ids of a 3dwindow object handled by the action method The action method should return one of the following two predefined contants _continue or _block If _continue is returned the runtime library will handle the event Returning with _block means that the runtime library will take no action in response to the event For example to keep the window from disappearing when closed by the user the overridden action method should return with _block instead of _continue 8 2 Mouse events The action method can be used to receive mouse related events The action method is called whenever the mouse is used within that window Attributes of the 3devent instance passed to the acti
32. or _3dmaterial _front_and_back can be assigned to the visibility attribute _front_and_back is the default value Let visibility car_door_material 3dmaterial _front 71 The _front side is defined by a counterclockwise winding of the vertices The right hand thumb rule can be used as mnemonic reminder If a fist is made with the right hand and the vertices of a polygon are ordered in the direction the fingers point then the thumb points out from the front of the surface 7 4 Using instances of 3dmaterial A caveat to using the 3dmaterial object is that each instance must be filed in a material_set before the object using it is rendered 3dmaterials should be filed into the set owned by the 3dworld in which it will be visible The 3dmodel also owns a material_set containing materials to be used within the model When a 3dmodel is read in from a file the material_set will be populated with all necessary 3dmaterial instances In the following example a spinning cube is shown The front and back surfaces reference a 3dmaterial showing a texture named cacilogo bmp Left and right side surfaces of the cube are displayed with the texture eagle bmp Top and bottom surfaces are colored with a light purple diffuse_color 1 0 0 6 1 0 The cube itself is derived from the 3dbox class found in the 3dshapes m subsystem Its motion method is overridden to call the rotate_x rotate_y and rotate_z methods allowing the cu
33. planes can be selected while the simulation is running In this example many of the concepts described in previous chapters are utilized including 87 E Overriding the 3dwindow s action method to get mouse input then calling select_node to determine which plane was clicked on E Overriding the 3dgraphic s draw method to construct the planes with program code E Overriding the motion method to allow customized motion Filing objects in the motion_Set E Creating and utilizing a 3dtext object to display a message in the window basic test of 3d graphics This program tests a simple simulation with many moving objects preamble including the gui m 3d m subsystems begin class sky_window every sky_window is a 3dwindow and overrides the action end begin class moving_jet every moving_jet is a 3dgraphic and has a color flight_angle flight_radius airspeed vertical_airspeed an elevation a draw_triangle method an init method and overrides the draw overrides the motion overrides the action ooo ow define color as an integer variable define flight_angle flight_radius airspeed vertical_airspeed elevation as double variables define draw_triangle as a method given 9 double arguments verticies after creating a moving_jet call init end define the_window as a sky_window reference variable define the_world as a 3dworld reference variable define the_light as a 3dlight reference variable define the_camera as
34. the file containing the image Currently only TARGA graphic tga files and Window Bitmap bmp files are supported JPEG files can be converted to BMP by a variety of windows programs The width and height of images should be a power of 2 for example 128 by 256 16 by 64 512 by 32 etc The 2d coordinates for a texture image range from 0 0 to 1 0 Coordinate are defined by an s axis and at axis The s axis is horizontal and the t axis is vertical with s 0 0 t 0 0 located at the lower left corner of the image and s 1 0 t 1 0 located at the upper right corner For texture coordinate values greater than 1 0 or less than 0 0 the mapping will be handled based on the values of the texture _wrap_s and the texture _wrap_t attributes When an attribute is set to _repeat the pixel image is repeated as s t values increase past 1 0 or decrease past 0 0 If the texture wrapping attributes are set to _clamp_to_edge the same pixel values found at s t 1 0 will be copied for all values of s t gt 1 0 Pixel values found at s t 0 0 will be repeated for s t lt 0 0 In some cases it is necessary to specify which sides of a surface can be made visible If the front or back side is always hidden some performance improvement can be made by marking that side as such The visibility attribute of 3dMaterial controls which sides are visible an invisible side will appear translucent when facing the 3dcamera define visibility as an intege
35. the unique vertices can be specified in the points array with index values of possibly multiple references stored in the indices array attribute Using this method can save memory and improve performance For example a cube consists of 8 unique vertices Using the _quads format without indexed vertex arrays to define the faces requires 24 vertices or a points array of dim 24 x 3 72 576 bytes Using vertex arrays the smaller indices integer array would contain the 24 elements to define zero based indices into the points array 96 bytes The points array would contain only the unique eight vertices or 8 x 3 24 elements 192 bytes The total memory requirement for the geometry is 192 96 288 bytes for index vertex arrays versus 576 bytes See below 5 4 indices attribute ae attribute et si a front face ae skO Ii 220 u90 front 1 areca EUEODTaUE 1 0 30807 P50 TE tt 3 2 6 7 bottom face teDeshety Lely ie tt 5 4 7 6 back face 7 6 eo wears e 1 0 1 0 1 0 4 back 1 0 POsi o rs L 5 6 2 right face 4 0 3 7 left face 3 2 1 0 1 0 1 0 6 SEADA nF Figure 7 Using the 3dfaces indices attribute to define a cube Three helper methods called set_point set_normal and set_texture_point can be used to assign values in the points normals or texture_points arrays respectfully The 1 based index is given followed by the vector or coordinates The corresponding array must
36. to the screen when the text is rendered Text drawn using these types of fonts will always appear right side up regardless of how the 3dtext object or its owner node is oriented However the 3dnode location properties is still utilized In other words the text can be positioned by calling the set_location method Bitmapped text will appear the same size regardless of its distance from the camera If a larger or smaller text size is needed a different font must be assigned to the font attribute 3dtext 9 by_15_ font 3dtext 8_by_13_font fixed width bitmap font fixed width bitmap font 1 3dtext times_roman_10_font variable width bitmap font 3dtext times_roman_24 font variable width bitmap font 3dtext helvetica_10_font yvariable width bitmap font 3dtext helvetica_12_font variable width bitmap font 3dtext helvetica_18_font yvariable width bitmap font 63 Text 1 Fonts S E Stroke font WWWWW iii Stroke mono font WWWWW 9 by 15 bitmap font 8 by 15 bitmap font Times Roman 10 point font Times Roman 24 point font Helvetica 10 font Helvetica 12 font Helvetica 18 font Figure 6 17 The text fonts For bitmapped fonts the align_horiz align_vert attribute allows the text to be centered or left right top bottom justified The following constants can be assigned to the alignment attribute define _left_justified 0 _centered _right_justified as constants
37. x2 y2 z2 dravw_vertex x5 y5 z5 draw_vertex x3 y3 z3 draw_vertex x6 y6 z6 Figure 6 13 The _line_strip format The _line_loop format is line the _ ine_strip format except that the last point is automatically connected to the first arav_vertex x4 y4 z4 arav_vertex x1 y1 z1 draw vertex x5 y5 z5 draw vertex x2 y2 z2 drav_vertex x3 y3 z3 draw _vertex x6 y6 z6 Figure 6 14 The _line_loop format Multiple widths and dash styles are supported When lines are being drawn the set_pen_size and set_pen_pattern class methods can be called to set the line width and pattern These methods must be called before begin_drawing The current pen size is always in pixels The pattern is one of the following constants _ solid _long_dash _dotted _dash_dotted _medium_dash _dash_dot_dotted _short_dash _alternate 59 A Lines 2 Test the line styles Figure 6 15 Line widths and constants passed to the set_pen_pattern method 6 7 Drawing points points are essentially 0 dimentional objects but are also located in 3 dimensions A point is represented by a visible dot If the _points format is passed to begin_drawing each call to draw_vertex will add a dot to the scene The size of these dots in pixels can be set by calling the set_pen_size class method For example suppose we want to draw a spiral shape The preamble would define a subclass of 3dgraphic called spiral
38. 0 8 0 call draw_triangle 0 0 2 0 27 0 0 0 7 0 8 0 60 0 2 0 8 0 call draw_triangle 30 0 0 50 57 0 30 0 0 50 57 0 0 0 0 50 40 0 call draw_triangle 0 0 0 5 40 0 30 0 0 5 57 0 0 0 4 0 57 0 call draw_triangle 0 0 4 0 57 0 30 0 0 5 57 0 0 0 0 5 40 0 call draw_triangle 30 0 0 5 57 0 30 0 0 5 57 0 0 0 4 0 57 0 call draw_triangle 0 0 0 5 40 0 3 0 0 5 57 0 0 0 25 0 65 0 call draw_triangle 0 0 25 0 65 0 3 0 0 5 57 0 0 0 0 5 40 0 call draw_triangle 3 0 0 5 57 0 3 0 0 5 57 0 0 0 25 0 65 0 call end_drawing end initialize the flight parameters randomly method moving_jet init let flight_radius uniform f 100 0 1500 0 1 let flight_angle uniform f 0 0 pi c 2 0 1 let airspeed uniform f 50 0 500 0 1 let elevation uniform 0 0 200 0 1 let vertical_airspeed uniform f 50 0 50 0 1 end This method is called automatically by the system Using the dt argument we can determine the next location and orientation using the current elevation airspeed and vertical airspeed method moving_jet motion dt add arcsin f min f 1 0 airspeed dt flight_radius to flight_angle add vertical_airspeed dt to elevation if elevation gt _max_elevation or elevation lt 0 0 let vertical_airspeed vertical_airspeed always call set_location flight_radius cos f flight_angle flight_radius sin f flight_angle call set_f
39. 3dmodel reference variable 3 Create windows worlds and groups 10 end create window let title window Use the arrow home and end keys to move the model create world file this world in world_set window 4 create camera s create camera call set_orientation camera 0 0 0 0 1 0 0 0 1 0 0 0 call set_location camera 0 0 0 0 100 0 file this camera in camera_set world 5 create light s create light let ambient_color light color rgb 0 4 0 4 0 4 let diffuse_color light color rgb 1 0 1 0 1 0 call set_location light 0 0 500 0 500 0 file this light in light_set world 6 create model s create model call read model ford 3ds file this model in model_set world 7 create material s materials for this example are created automatically when model is read 8 create objects used in the simulation ue a Create instances of 3dnode to represent the model on screen T Assign the model attribute to link the model to the 3dnode create the_car let model the_car model file this the_car in node_set world 9 Call the display method of the 3dwindow This will show the window call display window 10 Before starting the simulation activate the 3dwindow animate method This method will keep refreshing the window as often as possible as the simulation runs Do
40. E ES aaea SEs 108 SOMOGE CAE EEEE EEEE A EEE A eae iad 110 DINO Gate Sin Dade hacker aaa a Eo alate A a a e a a 113 3dpoints lineage 3dpoints gt 3dgraphic gt 3dnOde eee eeeeeeceeeeeeeeeeeceeeeeeeteeeees 118 3drectangle lineage 3dshapes m drectangle gt 3dshape gt 3dgraphic gt 3dnode 119 3dshape lineage 3dshapes m 3dshape gt 3dgraphic gt 3dnode eeeeeeeeeeeeees 120 3dsphere lineage 3dsphere gt 3dshape gt 3dgraphic gt 3dnode eee eeeeeeeeeeees 120 3dtext lineage 3dtext gt 3dgraphic gt 3dn0de 000 eee eesceceeneeceeeeeeceeeeeceeeeeeeneeeees 120 Bitmapped fonts scccisceciscees nnr ea danedeiased cas EARE S E NEE 121 3dwindow lineage 3dwindow gt gui m guiitem oe eee ceeneeceeeeeeceeeeeeeteeeeeeeeees 122 DWE i Sirens a Baaslos holy aay hind seers a bade dace el EG aad tester MR eet 124 Preface This document contains information on CACI s new SIMSCRIPT UI Modular Object Oriented Simulation Language designed as a superset of the widely used SIMSCRIPT II 5 system for building high fidelity simulation models It focuses on the description of the SIMSCRIPT III 3 D Graphics CACI publishes a series of manuals that describe the SIMSCRIPT II Programming Language SIMSCRIPT III Object Oriented 2 D and 3 D Graphics and SIMSCRIPT II development environment SimStudio All documentation is available on SIMSCRIPT WEB site http www simscript com products simscript_manuals htm
41. SIMSCRIPT III 3 D Graphics Manual CACI Copyright 2010 CACI Products Company All rights reserved No part of this publication may be reproduced by any means without written permission from CACI For product information or technical support contact CACTI Products Company 1455 Frazee Road Suite 700 San Diego CA 92108 Phone 619 881 5806 Email simscript caci com The information in this publication is believed to be accurate in all respects However CACI cannot assume the responsibility for any consequences resulting from the use thereof The information contained herein is subject to change Revisions to this publication or new editions of it may be issued to incorporate such change ii Table of Contents Tableof Contents ecscoie eet erie Geeta tA Oriel E atin rita ie tease aan 3 PIE E fe BG a E E E E EEE E 5 Tee InOc O 5 eed e a a i e ashe la Asal teehee BA A 7 1 1 A Typical 3d Graphics Program iiss scsicccitvedcasasacdeateeajeccdsseavananecsansvendoacds ontecens lesdeantans 8 1 2 Example code for a typical 3d graphics program sessssssesssesssseeesseesseessersseresses 10 ES Class TE CAR CIN Y oy cen ena E A E E E 12 Ds NG A a E E E E EEE 14 2 V The Sdworld aneia n asi Sterner ea aOR 14 2 2 Setting the location of a TOde ns isi vesiscisicvedarssteeinsvengsceei neadadaadessaceasdaide puusasaaeaceaeaeee 15 2 3 Setting the orientation of a node ssssssseessesssessseressetesseeessresseesseesseeeessees
42. Telephone 619 881 5806 www simscript com 1 Introduction The Simscript III 3d graphics package is an object oriented wrapper around the OpenGL toolkit The public preamble 3d m sim contains the basic class descriptions that allow the programmer to create windows containing 3d graphical scenes Camera and light objects can be created to implement realistic scenes in an object oriented fashion Hierarchical scene graphs allow the programmer to specify graphical objects called nodes as containing other objects positioning and orientation of a container node will automatically affect the position and orientation of the sub nodes it contains Each node in the scene graph represents a visible graphic in the window The node is implemented with the 3dnode class In order to see the nodes in the scene graph a Camera is necessary Each 3d program must create at least one camera and orient it properly in order to view the scene graph Multiple cameras are allowed and there viewports can be overlapped or tiled on the canvas of a 3d window A camera can also be attached as part of a scene graph allowing it to move or rotate with its parent node A 3dcamera class implements the camera Multiple light sources are allowed in a Simscript 3d graphics program A Light can be created a positioned and oriented with respect to the scene Light objects are also part of the scene graph and are implemented using the 3dlight clas
43. The application will define this dynamic behavior by implementing time elapsing process methods that will update the location rotation geometry etc of the visible scene graph The SIMSCRIPT II 3d graphics runtime library will automatically update the canvas of the 3dwindow that is showing the scene to concur with the attributes of the 3dnode objects in the scene graph 9 1 Frame Based Animation This updating is done differently than in the gui m 2d graphics In a 2d graphics application an attribute of a graphic object is assigned and the display method is then called to immediately update the appearance of that particular instance The SIMSCRIPT 3d graphics instead uses a frame based system for updating the canvas The image of each entire 3dworld scene graph is updated as often as possible without causing a noticeable lag in the expected runtime of the simulation The refresh rate depends on many factors including the complexity of the scene graph the time scaling factor and the size and scope of the simulation To start this automated updating of the window the 3dwindow animate process method must be activated after the 3dwindow is created This process method takes the duration in time units as its only argument If the duration is less than or equal to zero animate will run forever This process method must be running in order for mouse and keyboard events to work Update the window automatically for 10000 units activate a animate
44. _turret otherwise return with 3dmodel create_component component_name class_name end When the 3dnode load method is used it will make copies of all components in the model Individual attributes are copied by an internal call to the copy_attributes method Therefore if a component is subclassed as above and the load method is to be used the sub class must override this method if it defines attributes that need to be copied with the rest of the components In our tank example suppose the turret class defines attributes azimuth and attitude that are initializes in the model We want these values to be propagated when turret is copied via the load method Begin class turret Every turret is a 3dnode and has A azimuth An attitude and Overrides the copy_attributes Define azimuth attitude as double variables End The copy_attributes method s implementation would look like this method turret copy_attributes node define p as a pointer variable define original_turret as a turret reference variable let p node necessary due to original prototyping let original_turret p let azimuth azimuth original_turret let attitude attitude original_turret call 3dnode copy_attributes node end 40 In the next example a tank model is used that has its turret represented by a subcomponent called turret Three sub classes are defined in the preamble tank_model a subclass of 3dmo
45. _x the_camera omega now rotate camera about its X axis let mouse_x x event save last mouse position let mouse_y y event always case 3devent _mouse_up let drag_on 0 case 3devent _mouse_wheel_forward zoom in by changing depth of field let dof_angle max f dof_angle 2 5 call set_perspective the_camera dof_angle 1 0 _nearp _farp 1 case 3devent _mouse_wheel_back zoom out by changing depth of field let dof_angle min f dof_angle 2 175 call set_perspective the_camera dof_angle 1 0 _nearp _farp 1 default endselect return with _continue tell SIMSCRIPT to do default handling end main 78 define window as a my_window reference variable define world as a define light as a define model as a define the_car as Create windows create window let title window 3dworld reference variable 3dlight reference variable 3dmodel reference variable a 3dnode reference variable worlds and groups Drag the mouse and use wheel to change the view let dof_angle window 60 create world file this world in world_set window create camera s create the_camera call set_forward the_camera 0 0 0 0 1 0 call set_location the_camera 0 0 0 0 2 5 call set_perspective the_camera dof_angle window 1 0 _nearp _farp 1 file the_camera in camera_set world create light s create light call set_location light 0 0 500 0 500 0 file this light in lig
46. a 3dcamer can Lights are positioned and oriented using methods inherited from 3dnode 4 1 Determining the variety of lighting In addition the 3dlight class adds a variety attribute which defines the characteristic nature of the light source The three varieties are _directional positional and _spot Value for variety Description 3dlight directional Light has no fixed position but emanates uniformly from a single direction The set_forward method can be used to set the direction vector The set_location method has no effect This light is useful for mimicking sunlight or light from a far away source This is the default variety of 3dlight 3dlight _ positional Light emanates uniformly in all directions from a single source The set_location method can be used to set the location of the source 3dlight _spot This variety has both direction and positional characteristics It is shown as a cone of light emanating from a fixed point set_location method and traveling in a certain direction set_forward method The spot_cutoff attribute is used to set the angle in degrees See figure 4 1 spot_cutoff degrees Figure 4 1 The spot_cutoff attribute A good example of the use of positional lighting would be the SIMSCRIPT III parking lot demo This program sets up a parking lot simulation at night Lamp posts are positioned at strategic locations around the parking lot A 3dl
47. all set_orientation light 0 0 1 0 0 0 1 0 file this light in light_set world call display window show every thing let timescale v 100 l second per 1 unit simulated time activate a animate window 10000 now start simulation end 56 Example 8 A soda can torus noe f fam Figure 6 10 Texture mapped torus 6 6 Drawing points and lines The begin_drawing method will accept line and point formats as well as surface formats Lines are 1 dimensional but are constructed with 3d coordinates These objects are useful as annotations In Figure 6 11 a line loop is used to delineate the orbits of the planets 57 SIMSCRIPT II Model of the solar system o JE Figure 6 11 Using the _line_loop format to mark planetary orbits Line related formats constants that can be passed to the begin_drawing method include _lines _line_strip and _line_loop The _lines format is used for drawing multiple line segments Successive calls to the draw_vertex method mark the endpoints of the segments draw vertex x1 y1 z1 araw_vertex x4 y5 24 ed p Doae A A ees Oty draw vertex x2 y2 z2 draw_vertex x5 y5 z5 ion drav_vertex x3 y3 z3 draw_vertex x6 y6 Z6 Figure 6 12 The _lines format 58 The _line_strip format is used to draw a polyline In this format a new segment is added each time draw_vertex is called draw vertex x4 y4 z4 dravw_vertex x1 y1 z1 draw vertex
48. apes m Simple cylinder shape length radius attributes 3dellipse 3dshapes m 2d circle arc pie or ellipse in 3d radius_x radius_y space start_angle stop_angle 3drectangle 3dshapes m 2d rectangle in 3d space height width 3dsphere 3dshapes m Simple sphere shape radius 66 7 Surfaces Textures and Materials Surface attributes are important for displaying 3d objects Accurate specification of the shininess color and texture of a surface are important for realistic images In the SIMSCRIPT 3d graphics the 3dmaterial object defines the skin of the object being drawn It is not derived from 3dnode and therefore does not belong in a scene graph Instead various object classes reference the 3dmaterial For example objects derived from 3dshape also have a material attribute that an instance of a 3dmaterial object can be assigned to 7 1 Setting the color and shininess of a surface Colors in SIMSCRIPT 3d graphics are specified in an RGB red green blue triple with element values ranging from 0 to 1 The rgb method of the color class in gui m is used to encode color from RGB values into an integer For example to obtain a dark green color Define dark_green as an integer variable Let dark_green color rgb 0 0 0 5 0 0 A 3dmaterial can be used to define the reflectivity of a surface with respect to diffuse ambient and specular colored light The diffuse_color ambient_color and specular_color attributes are use
49. as any other geometric shape with regard to 62 its transformation from world to canvas like the text on a stop sign In this case a vector font should be chosen However if text is used for tagging or as a simple message we may not want it to appear larger or smaller as is moves closer or farther from the camera In this case a raster font is used To add some detail Vector fonts A vector font is rendered by drawing a series of line segments in 3 dimensions Vector text follows the same rules as do other 3dgraphic shapes with regard to location and orientation The advantage of using this type of text is that it is part of the object for example the text on a road sign or the monogram on the side of an airplane The text will increase in size as the camera moves closer to it The disadvantage is that the text is usually composed of thin lines and may not look good when it is sized big The following vector fonts are available 3dtext stroke_font Variable width vector font 3dtext stroke_mono_font Fixed width vector font The size of vector text is controlled by its width and height attributes These attributes function the same as the width and height for the 3drectangle class do The height defines the maximum height including descenders and the width applies to the whole text string Bitmapped fonts Characters in a bitmapped or raster based font are basically small 2d bitmap images that are copied
50. ate an instance of a 3dwindow object Call methods to set size position and title b Create instances of the 3dworld object Usually only one world is needed unless you are implementing a control panel heads up display or the application requires multi layered graphics c File 3dworld instances into the world_set owned by the 3dwindow object d If a hierarchy or groupings of objects is needed create instances of the 3dnode object File them into the node_set owned by the 3dworld in which they are to be used They can otherwise be filed into the node_set owned by another node 4 Create camera s a For each view of the scene create an instance of a 3dcamera object b Set the location and orientation of the camera so that it is some distance from the scene but is pointing at the scene If necessary call other methods to customize the view c File instances into the camera_set owned by the 3dworld showing the view d A 3dcamera can also be attached to a 3dnode allowing its position and orientation to be determined by the parent node If necessary the 3dcamera object can ALSO be filed into a node_set 5 Create light s if necessary a For each light illuminating the scene create an instance of a 3dlight object b Set the location of the light appropriately For spot lights it may be necessary to set the orientation also c File instances into the light_set owned by the 3dworld showing t
51. be reserved beforehand and must be large enough to store the vector at the specified index define set_normal as a method given 1 integer argument index 3 real arguments nx ny nz normal vector This helper method assigns one of the normal vectors in the normals array to nx ny nz define set_point as a method given 1 integer argument index 3 double arguments px py pz coordinates of vertex This helper method assigns a point vertex in the points array to pPX PY PZ define set_texture_point as a method given 1 integer argument index 2 real arguments EP CSy it This helper method assigns a texture coordinate in the texture_points array to s t Another helper method called compute_normal_vectors can be called to automatically assign normal vectors to the normals array based on the geometry in the points array and 101 the format attribute This method does not automatically smooth the surface and will result in a faceted look The normals arrays must be reserved and the points and format attributes assigned before calling compute_normal_vectors 3dgraphic lineage 3dgraphic gt 3dnode The 3dgraphic is the base class for all objects whose geometry is defined by program code and not by offline models stored in a file Classes derived from 3dgraphic can be seen by a 3dcamera and illuminated by a 3dlight Since 3dgraphic is derived from 3dnode instances must be filed into a node_set owned
52. be set before the model is read from the file They are _smoothing and _cache_model The options are set via a left handed use of the enabled method For example define the_model as a 3dmodel reference variable let enabled the_model 3dmodel smoothing 1 turn on smoothing let enabled the_model 3dmodel smoothing turn off smoothing oO The _smoothing option will cause normal vectors to be recomputed at the time the model is read from the file This will give the surfaces in the model a smooth appearance It is off 0 by default 43 The _cache_model option if on will cause the runtime library to create an internal call list for the model at the time a 3dnode which references it via the model attribute is first drawn For the case of multiple 3dnode objects referencing the same static model this will improve performance This option is not relevant if the load method is used to link the 3dnode to the model After a model is read its size can be determined if necessary The get_bounding_box method can be called to get the dimensions of a model in the x y and z directions define get_bounding_box as a method yielding 3 double arguments xlo ylo zlo 3 double arguments xhi yhi zhi Computes the smallest 3d box that wil nclose the model Must be called after read to be effective Instances of 3dmodel must be filed into the model_set owned by the 3dworld in whic
53. be to spin about its x y and z axes Example 6 spinning cube with texture mapped surfaces preamble including the 3d m 3dshapes m subsystems begin class spinning_box every spinning_box is a 3dbox and has a X_Spin_rate a y_spin_rate a z_spin_rate and has a spin process method overrides the motion define x_spin_rate y_spin_rate z_spin_rate as double variable end define camera as a 3dcamera reference variable define world as a 3dworld reference variable end method spinning_box motion dt call rotate_x x_spin_rate dt call rotate_y y_spin_rate dt call rotate_z z_spin_rate dt end process method spinning_box spin let x_spin_rate 90 wait 4 0 units let x_spin_rate 0 let y_spin_rate 180 wait 10 0 units let y_spin_rate 0 let z_spin_rate 360 wait 4 0 units end main 72 define define define define variables lr_material tbh_material create the window create window let title window Example 6 create the world create world r window as a 3dwindow reference variable light as a 3dlight reference variable box as a spinning_box reference variable fb_material as 3dmaterial referenc Showing a 2d image using texture mapping let ambient_color world color rgb 0 2 0 2 0 2 file this world in world_set window create the camera create camera call set_perspective camera 60 0 1 0 0 1 100 0 1 call set_location camera 0 0 0 0
54. built When the location or orientation of a 3dnode is changed all 3dnode instances attached to the scene graph via the node_set are repositioned as well In order to be made visible a 3dnode must be attached to a scene graph The scene graph is rooted at the 3dworld object which also owns a node_set Visible nodes must therefore be filed in a node_set owned by either another 3dnode or a 3dworld See Figure 13 world set 3dworld battlefield 3d world control panel node set 3dnode terrain 3dnode 3dnode ground obsticles 3dnode body 3dnode turret node_set 3dnode thousing Figure 13 A scene graph including window and worlds An instance of a 3dnode can therefore be used to create groups of objects Moving or rotating the 3dnode representing the group will move rotate all nodes in the group Complex objects can be divided into sub nodes For example a 3d tank may contain a turret sub node which in turn contains a cannon node Moving the tank will also move both the turret and gun Rotating the turret will also rotate the cannon Before a 3dnode can be destroyed it must first be removed from any owner set Destroying a 3dnode will automatically destroy nodes contained in its node_set To prevent this from happening nodes should be removed from the set prior to executing the destroy statement Properties of the 3dnode are it
55. cation_x location_y and location_y attributes If the camera is attached to a scene graph this location is with respect to the parent node set_orientation fx fy fz ux uy uz set the forward vector lt fx fy fz gt and the up vector lt ux uy uz gt set_forward fx fy fz sets the forward vector lt fx fy fz gt The camera will point in this direction aim x y Z causes the camera to point at the given target location The target location is specified in global world coordinates rotate ax ay az degrees rotates the camera about the given axis by the given number of degrees 22 rotate_x degrees rotate_y degrees rotate_z degrees spins the camera about its local x y or z axis by the given number of degrees As and example we will analyze how the view was set up in Example 2 In this case the world was oriented with respect to the viewer as follows a Its positive X axis is pointing to the right b Its positive Y axis up vector is pointing straight up c Its and its positive Z axis is pointing at the viewer The default up vector is to point straight up so it is not necessary to set this in other words calling the set_forward method is sufficient If the positive Z axis is to point toward the viewer the camera should point in the opposite direction or along the negative Z axis call set_forward my_camera 0 0 0 0 1 0 Figure 3 1 Camera ori
56. ccessing sub components of a 3dmodel create the world create world file this world in world_set window 42 create camera place it along positive z axis but point it down the negative z direction create camera call set_perspective camera 90 0 1 0 5 0 115 0 1 call set_forward camera 0 0 0 0 1 0 call set_location camera 0 0 4 0 60 0 file this camera in camera_set world create a light source and point it in the same direction as the camera create light call set_forward light 0 0 0 0 1 0 file this light in light_set world create the one model for the tank create tank_model call read tank_model tank 3ds file tank_model in model_set world create the tank node create the_tank call load the_tank tank mogel copy components of tank to node let p find the_tank turret1 locate the turret1 node let the_turret p file the_tank in node_set world Tadd to root of scene graph file the_tank in motion_set file the_turret in motion_set call display window bring up the main window and show everything activate a movement the_tank now activate a movement the_turret now Tour process method activate a animate window 10000 now tell window to show animation let timescale v 50 50 100 real seconds per unit of time start simulation end 5 7 Misc 3dmodel options There are a couple more options regarding the 3dmodel that can
57. city or move_to methods An application can override this method to provide customized motion such as rotation or non linear movement For example suppose we want to use this technique instead of the process method to move the car from 20 0 0 0 0 to 20 0 0 0 0 The move_it process method would be rewritten as below Notice that using this technique only one wait statement is performed process method car move_it 85 define _speed 10 0 as constants file this car in motion_set call set_location 20 0 0 0 0 0 call set_velocity _speed 0 0 0 0 wait 20 0 20 0 _speed units remove this car from motion_set end For simple linear motion there is yet another way to move an object The 3dnode class defines a process method called move_to This process method will automatically compute the velocity and time to wait for the move Using the move_to process method we no longer need the move_it method The following code is added to the initialization file the_car in motion_set call set_location the_car 20 0 0 0 0 0 activate a move_to the_car 20 0 0 0 0 0 10 0 now 9 4 Moving Car Example The following represents the simplest way to achieve linear motion that is driven by a simulation A model of a car is initialized and its 3dnode move_to method is activated at time 0 0 This method will move the car from 20 0 0 0 0 0 to 20 0 0 0 0 0 automatically during the simulation Example of moving a gra
58. class 3drectangle lineage 3dshapes m drectangle gt 3dshape gt 3dgraphic gt 3dnode The 3dRectangle is derived from 3dshape and provides an easy way to add rectangular shapes to the scene graph Each 3drectangle instance lies in the x y plane with the positive z axis pointing up from the front Since the super class is 3dnode a 3drectangle instance inherits the location and orientation properties allowing it to be rotated and positioned The width and height attributes of the rectangle instance set the size of the object The 3dshape material attribute can be assigned a 3dmaterial instance to set the color and texture of the front and back faces If the material has a texture it may be necessary to cover the rectangle with a sub rectangle of the full texture image The texture_xlo texture_ylo texture_xhi and texture_yhi can be used to delineate a box within the image that will be mapped to the surface of the 3drectangle See Figure 17 texture_xhi texture_yhi 3drectangle texture_xlo texture_ylo Figure 17 3drectangle using texture_xlo texture_ylo texture_xhi and texture_yhi 119 3dshape lineage 3dshapes m 3dshape gt 3dgraphic gt 3dnode This class is found in the 3dshapes m module and is the base class for many shape primitive objects that are provided Basically a shape is defined for our purposes as an object whose geometry i e points and normal vectors are computed au
59. d an instance of a 3dmaterial object A 3dmaterial can be used to define reflectivity a surface has to diffuse ambient and specular colored light see 3dLight The diffuse_color ambient_color and specular_color attributes are used for this purpose define ambient_color diffuse_color specular_color as integer color reference variables monitored on the left ambient_color DEFAULT color _ white diffuse_color DEFAULT color _white specular_color DEFAULT color _black For specular light the shininess attribute relates to the specular exponent of the surface This value must range from 0 to 1 Higher values lead to smaller sharper highlights whereas lower values result in large and soft highlights If the surface is to be shiny i e metallic in nature both the specular_color and shininess attributes should be large 108 Texture mapping is also supported through the 3dMaterial class Texture mapping allows a 2d pixel image such as a windows BMP file to be plastered onto a 3d surface The mapping of 3d geometry to 2d points in the image file is done using texture coordinates see 3dgraphic draw_texture_coordinate Basically when draw_texture_coordinate is called before draw_vertex the 2d texture coordinate is mapped or attached to the 3d vertex The result is a smooth texturing of the 2d image over the surface The texture_name attribute of 3dmaterial can be assigned the name of
60. d for this purpose For specular light the shininess attribute relates to the specular exponent of the surface This value must range from 0 to 1 Higher values lead to smaller sharper highlights whereas lower values result in large and soft highlights If the surface is to be shiny i e metallic in nature both the specular_color and shininess attributes should be large In Figure 7 1 the ambient diffuse and specular color for the red paint on the car shown in Example 1 is displayed The diffuse color is a dark red with the RGB triple set to 0 56 0 02 0 02 The surface will reflect this color in all directions The ambient color is set to 0 02 0 0 0 0 The unlit portions of the car will reflect this very dark red color The specular color is set to 1 0 1 0 1 0 This means that the shiny portions of the car will be white 67 Attributes of selected 3dmaterial Name Cherry Red Metal ambient_color R 0 02 G o o0 B 0 00 diffuse_color R 0 56 G 0 02 B 0 02 specular_color R 1 00 hoo B h oo shininess 10 65 z View 3d objects n on ox Figure 7 1 Color and shininess of car shown in Example 1 7 2 Texture mapping and raster images Texture mapping is also supported through the 3dmaterial class Texture mapping allows a 2d pixel image such as a windows BMP file to be plastered onto a 3d surface For larger surfaces the texture is repeated along the surface much li
61. d graphics color rgb 0 1 0 2 0 5 create the world create the_world file the_world in world_set the_window create the camera create the_camera set_forward the_camera 0 0 0 0 1 0 set_location the_camera 0 0 500 0 1500 0 set_perspective the_camera 60 0 1 0 1 0 3000 0 1 this the_camera in camera_set the_world call call call file create the axis graphics for i 1 to _num_planes do create plane let color plane color rgb 0 5 random f 1 random f 1 let name plane names i 90 end file this plane in node_set the_world file this plane in 3d m motion_set loop create a text message using the 3dtext object give it a raster font so that its size will not depend on its distance from the camera create the_messag call set_location the_message 250 0 250 0 0 0 let font the_message 3dtext times_roman_24_ font let string the_message Click on a plane file the_message in node_set the_world simulate sunlight using a directional light from the top create the_light let ambient_color the_light color _black let diffuse_color the_light color _white let variety the_light 3dlight _directional call set_forward the_light 0 0 1 0 0 0 point straight down file this the_light in light_set the_world let ambient_color the_world color rgb 0 0 0 0 0 3 call display the_window activate a animate the_window 1000 now
62. d will shift the position of a node by a movement right up and forward with respect to its own axes The node s location will be moved along its local x axis y axis and z axis by the three given values move passenger 2 10 units forward call move passenger 2 0 0 0 0 10 0 rdx dy dz 2 5 Rotating a node It is also possible to spin a 3dnode on one of its three local axes The rotate_x rotate_y and rotate_z methods will do just that Each method takes an angle in degrees as an argument and spins the 3dnode by that amount about the local not owner axis These methods are similar to the move method in that they take delta values instead of absolute values For example if an airplane is pointed forward along its positive z axis call the rotate_x method will pitch up or down In this case the local Y and Z axes are rotated but the X axis will remain unchanged Calling the rotate_y method will yaw about its y axis Calling the rotate_z method will roll the airplane define rotate_x rotate_y rotate_z as method given 1 double argument Tangle in degrees The local axes of a node are rotated with the node itself For example in Figure 10 a box is first rotated about the z axis the moved by 100 0 units in the Y direction up 17 Y Z xX 2 gt ye X Sn i call move 0 100 0 Figure 2 3 Calling rotate_z followed by move 2 4 Scaling a node The scale method will modify size of the
63. de event Case 3devent _up_key thandle up key Case 3devent _down_key handle down key Case 3devent _left_key handle left key Case 3devent _right_key handle right key Default Endselect Always End Calling the display method will make the window visible If the window is already visible the canvas will be updated to show a current image for all 3dworlds and 3dnodes that are contained in the window During a simulation there are usually objects changing location orientation and appearance over time To make sure that the image of the scene graph is kept up to date the animate process method can be activated The animate method is scheduled to allow the window canvas to be update automatically during a simulation define animate as a process method given 1 double argument run length for animation Animate takes one argument which determines how long in simulation time units to run the process method The method will run indefinitely if 0 is passed The display method is called repeatedly by animate in between event notices It is important to know that it at this point the draw method may be called for instances of 3dgraphic objects contained in the scene graph Canceling the process method will stop the automatic animation 3dworld A 3dWorld acts as a container for lights cameras and graphics One or more 3dworld instances must be created and filed in the world_set owned by 3dwindow
64. del tank a subclass of 3dnode and turret another subclass of 3dnode The tank_model class will override create_components to create and instance of a turret object when turret1 is passed as the component name Both the tank and turret subclasses will define a process method called movement Each process method will be implemented in a unique fashion to allow simultaneous but different motion Preamble including the 3d m 3dshapes m subsystem begin class tank_model every tank_model is a 3dmodel and overrides the create_component end begin class tank every tank is a 3dnode and has a speed spin_rate forward process method spin process method movement process method overrides the motion define speed spin_rate as double variables define spin forward as process methods given 1 double argument ooo wo end begin class turret every turret is a 3dnode and has a spin_rate a spin process method a movement process method overrides the motion define spin_rate as a double variable define spin as a process method given 1 double argument end define window as a 3dwindow reference variable end method tank_model create_component component_name class_name define my_turret as a turret reference variable if component_name turret1 and class_name 3dnode create a turret called my_turret return with my_turret otherwise return with 3dmodel create_component component_name class_name end process method tank
65. draw_vertex as a method given 3 double arguments a part ae The draw_vertex draw_normal and draw_texture_coordinate methods MUST be called between begin_drawing and end_drawing methods Other class methods can be called to set features for drawing materials and lines The set_color method can be used to define surface color or if called before draw_vertex can set the color applied to individual vertices define set_color as a method given 1 integer argument front _back or _front_and_back 1 integer argument ambient _diffuse _specular 1 integer color argument color color rgb r g b The first argument indicates which side the color should be applied to and must be _front _back or _front_and_back The second gives the type of lighting _ambient _diffuse or _specular that should reflect the color see 3dlight The third argument is the color value obtained from the gui m color rgb class Attributes of the 3dmaterial object colors and texture can be applied to drawings as well The set_material method can be called before begin_draw and takes a 3dmaterial instance as an argument This instance must be filed in the 3dworld material_set before the draw is invoked 103 define set_material as a method given 1 3dmaterial reference argument pointer to material When lines are being drawn the set_pen_size and set_pen_pattern methods can be called to set the line width and pattern define set_pen_size as a met
66. e negative z axis The ortho_xlo ortho_xhi ortho_ylo ortho_yhi ortho_zlo ortho_zhi and ortho_autosize attributes are set When using a perspective projection distant objects will appear smaller This form of projection provides a more realistic view The set_perspective method is used to specify the attributes of a perspective projection The distance from the camera to both the near and far clipping planes is specified as well as the angle in degrees of the view from the location of the camera Decreasing the angle of view has the same effect as zooming in with a traditional camera define set_perspective as a method given 1 double argument Tangle gt 0 0 lt 180 0 degrees 1 double argument aspect ratio 2 double arguments near far clipping planes 1 integer argument 1l gt compute aspect ratio after win resize sets up a perspective viewing transformation The view angle is relative to th ye The aspect ratio will equal the width of the projection divided by its height The location of clipping planes is specified relative to the camera Geometry in front of the near or behind the far clipping planes is clipped By default a camera will use the perspective projection 94 A camera can be programmed to track point at a particular 3dnode object that is filed in the same world_set Assigning the tracked_node attribute to a 3dnode instance will cause the camera to
67. e a background node to hold the objects create background file this background in node_set world add to root of scene graph create the one model for the tank create tank_model call read tank_model tank 3ds file tank_model in model_set world create the tank node create the_tank let model the_tank tank_model file the_tank in node_set world Tadd to root of scene graph file the_tank in motion_set create the model for the cone create cone_model call read cone_model cone 3ds file this cone_model in model_set world create many cones and space them out reserve cones as _num_cols_cones by _num_rows_cones for i 1 to _num_rows_cones for j 1 to _num_cols_cones do create cones i j let model cones i j cone_model cones share the same model call set_location cones i j i 10 55 0 0 0 3 10 55 0 file this cones i j in node_set background add node to scene graph loop call display window bring up the main window and show everything activate a movement the_tank now our process method activate a animate window 10000 now tell window to show animation let timescale v 10 10 100 real seconds per unit of time start simulation 20 3 Example 2 create a simple scene with O x Figure 2 4 Example 2 A tank maneuvering through traffic cones 21 3 Cameras and Lights Every 3d graphics program must have at least one camera to vi
68. e current ring to the current vertex Figure 6 8 A torus composed of rings made of quad strips 50 Sub classing the 3dgraphic class will allow us to add additional attributes that parameterize the torus such as the major and minor radii and the number of facets The complete code is shown below Example 7 a 3d torus preamble for the toruses system including the 3d m subsystems begin class torus every torus is a 3dgraphic and has a material numMajor numMinor minorRadius majorRadius and overrides the draw oo 9 define material as a 3dmaterial reference variable define numMajor numMinor as integer variables define minorRadius majorRadius as double variables end end this method is called automatically We will provide the code needed to draw a torus method torus draw define nx ny nz as double variables define a0 al x0 y0 x1 yl as double variables define b c r z majorStep minorStep as double variables define i j as integer variables let majorStep 2 0 pi c numMajor let minorStep 2 0 pi c numMinor call set_material material for i 0 to numMajor 1 do a0 i majorStep al a0 majorStep x0 cos f a0 yO sin f a0 xl cos f al yl sin f al call begin_drawing _quad_strip for j 0 to numMinor do b j minorStep c cos f b r minorRadius c majorRadius z minorRadius sin f b First point call 3d m vector_normalize x0 c y0 c z minorRad
69. e location in the owner node s coordinate system The fourth argument is the speed and must be positive A simulation can wait for a node to arrive at the location by calling the move_to method instead of scheduling it In either case the instance must be filed in the motion_set before the move_to process method is activated define move_to as a process method given 3 double arguments x y z destination 1 double argument speed in units second define car as a 3dnode reference variable start simulation file this car in motion_set call set_location car 100 0 0 0 0 0 start at 100 0 0 call move_to car 100 0 0 0 0 0 200 0 move to 100 0 0 A 3dnode object may be used to display a model obtained from a 3dmodel instance The load method can be called to copy the graphics from an existing 3dmodel instance that has itself been loaded via the 3dmodel read method Using the load method instead of assigning the model attribute is necessary if the program needs to modify sub nodes originally defined by the model For example a tank model may have a turret sub node which must be rotated with respect to the tank I this case each tank node in the world may have a different turret orientation or position with respect to the tank therefore it is not possible redisplay the same tank image in multiple locations When load is used new instances of sub nodes are copied from the 3dmodel to the node_set
70. ed top cell _tight_justified _left_justified _top_cell _top_cell i 7 sn _left_justified Pa J right_justified _bottom_cell bottom cell _centered bottom_cell _centered middle Figure 18 3dtext alignment 121 3dwindow lineage 3dwindow gt gui m guiitem The 3dwindow represents a window that can be resized or moved much the same as other windows shown on screen The window is made up of a resizable frame bordering a canvas It is the canvas that displays one or more 3dworld instances which in turn contain the 3dnode objects composing the scene graph Currently only the 3dwindow class has the capability to display 3d graphics The 3dwindow can also respond to user events such as window such as an attempt to move resize or close the window Asynchronous keyboard input is supported via the 3dwindow To display a 3dwindow an instance should first be created Since the 3dwindow is the top level item in the scene graph it is not filed into any set The title attribute can be assigned to set the title bar text The window s initial size and position is controlled by the position_xlo position_ylo position_xhi and position_yhi attributes Like the gui m window class the position is set in screen coordinates The 0 0 0 0 coordinate is located at the bottom left corner of the computer screen while 32767 0 32767 0 is located in the upper right corner The Microsoft Windows start bar is ignored The color attribu
71. efreshes of the screen The update_drawing method must be called for draw to be invoked again This use is most common _always Draw will be called each time the canvas is refreshed This is useful for objects with constantly changing geometry 6 8 Classes with retained geometry There are several classes derived from 3dgraphic that are provided in the 3d m and 3dshapes m subsystems When implementing objects derived from these classes the draw method is NOT overridden Instead these classes provide attributes and methods for specifying the shape of the graphic These classes are useful when the graphic object is static In other words the geometry and the number of points normals does not change during the simulation In addition the 3dfaces 3dlines and 3dpoints classes support indexed geometry which may improve performance These classes are shown below and documented more thoroughly in the subsequent reference section Class name Subsystem Description Geometry attributes 3dfaces 3d m Tessellated surface triangles quads points normals attributes 3dlines 3d m Line segments in 3d space points width attributes 3dpoints 3d m Single points in 3d space points size attributes 3dtext 3d m 2d text in 3d space string width height font 3dbox 3dshapes m Cubes rectangular boxes width height depth 3dcone 3dshapes m Simple cone shape length radius attributes 3dcylinder 3dsh
72. el It is off 0 by default The _cache_model option if on will cause the runtime library to create an internal call list for the model at the time a 3dnode which references it via the model attribute is first drawn For the case of multiple 3dnode objects referencing the same static model this will improve performance This option is not relevant if the load method is used to link the 3dnode to the model After a model is read the size of the model can be determined if necessary The get_bounding_box method can be called to dimensions of a model in the x y and z directions define get_bounding_box as a method yielding 3 double arguments xlo ylo zlo 3 double arguments xhi yhi zhi Computes the smallest 3d box that will enclose the model Must be called after read to be effective 112 Instances of 3dmodel must be filed into the model_set owned by the 3dworld in which the model is to appear This must be done before the window is displayed Materials used in the model are automatically filed into the material_set owned by 3dmodel when the 3dmodel read method is called 3dnode The 3dnode object is the base class of all objects that can appear in a 3dworld Nodes are used to build the scene graph This is a directed acyclic graph that represents the spatial relationship between objects A node owns a set of nodes called node_set and may also belong to a node_set allowing a hierarchy to be
73. ence variable 27 end process method tank movement define spin forward as double variables define _spin_speed 20 _forward_speed 2 as constants open unit 1 for input name is example2 dat use unit 1 for input let eof v 1 while eof v do read spin forward 1 and visible window lt gt 0 rotate the tank let spin_rate _spin_speed sign f spin wait abs f spin _spin_speed units let spin_rate 0 move the tank forward let speed _forward_speed wait abs f forward speed units let speed 0 0 loop close unit 1 end four motion method will be called automatically as simulation time Tadvances method tank motion dt call 3dnode motion dt call rotate_y dt spin_rate call move 0 0 0 0 dt speed end main define world as a 3dworld reference variable define tank_camera lot_camera as 3dcamera reference variables define light as a 3dlight reference variable define tank_model cone_model as a 3dmodel reference variable define background as 3dnode reference variables define the_tank as a tank reference variable define cones as a 2 dim 3dnode reference variable define _num_rows_cones 11 _num_cols_cones 11 as a constant define i j as an integer variable create the window create window let title window Example 3 Using cameras to show different views of the same scene call display window display the window now so that we know the size of the canvas crea
74. entation for Example 2 Now that we have defined how the coordinate axes are oriented with respect to the viewer the position of the camera must be specified But there must first be some idea of how big the scene graph is in terms of coordinate space so that we know how far away from the scene to place the camera from the scene We must also know where the scene is in the coordinate space In Example 2 the scene is geographically centered at the 0 0 0 point And since our camera is pointing along the negative Z axis it must be placed along the positive Z axis with respect to the scene graph The scene is specified in meters The tank moves about an area which is about 100 by 100 meters and is located in the x z plane Placing the camera about 10 meters beyond the boundaries of the lot will allow most of the scene to be in view Since the lot is centered about 0 0 0 we place the camera at z 60 Also in order to see the traffic cones that are far away the camera should be placed a few meters up in the air 23 call set_location camera 0 0 4 0 60 0 3 2 Setting up the viewing plane The next consideration is for setting up the camera s projection Two methods are available for doing this set_perspective and set_orthographic Usually you will want to use a perspective projection The set_perspective method sets the cameras near and far clipping planes as well as the aspect ratio of its width to height and the angle of view
75. era canvas_width window 2 0 canvas_width window 2 canvas_height window 1 file this lot_camera in camera_set world make the lot_camera track the tank let tracked_node lot_camera the_tank create the model for the cone create cone_model call read cone_model cone 3ds file this cone_model in model_set world create many cones and space them out reserve cones as _num_cols_cones by _num_rows_cones for i 1 to _num_rows_cones for j 1 to _num_cols_cones do create cones i j let model cones i j cone_model cones share the same model call set_location cones i j i 10 55 0 0 0 3 10 55 0 file this cones i j in node_set background add node to scene graph loop activate a movement the_tank now our process method activate a animate window 10000 now tell window to show animation let timescale v 10 10 100 real seconds per unit of time start simulation end 29 Example 3 Using cameras to show different views of the same scene m x Figure 3 5 Example 3 Tank program updated to include two viewports and tracking 30 4 Lighting up a scene graph As all objects in the scene graph as smooth shaded light source s are needed to apply the shading A light source can be added to the 3dworld by creating one or more instances of a 3dlight object The 3dlight class is derived from 3dnode and can reside in in a scene graph much the same way that
76. era and attach it to the tank itself The view from the tank is to appear on the left side of the canvas while the view from the parking lot appears on the right side Basically we will be setting up each camera as in Example 2 but will be adding the code call set_viewport tank_camera 0 0 canvas_width window 2 canvas_height window 1 call set_viewport lot_camera canvas_width window 2 0 canvas_width window 2 canvas_height window 1 3 5 Tracking a moving object with the 3dcamera Another attribute of the 3dcamera called tracked_node can be assigned allowing the camera to automatically track or point at another node in the scene graph In other words the tracked node will always appear in the center of the camera s viewport regardless of its position As the node is tracked the camera will align its local up vector with the global Y axis in order to keep the view from tilting Example 2 can easily be modified to allow the camera to track the moving tank by adding one line of code Let tracked_node lot_camera the_tank The fully updated version of Example 2 which we call call Example 3 is below Example 3 updated tank program Preamble including the 3d m 3dshapes m subsystem begin class tank every tank is a 3dnode and has a speed a spin_rate a movement process method overrides the motion define speed spin_rate as double variables end define window as a 3dwindow refer
77. es a 3dmaterial instance as an argument This instance must be filed in the 3dworld material_set at initialization define set_material as a method given 53 1 3dmaterial reference argument pointer to material The shininess of the surface used for specular lighting is set by calling the set_shininess class method define set_shininess as a method given 1 integer argument front _back or _front_and_back 1 double argument shininess 0 0 to 1 0 The first argument must be one of the constants _front _back or _front_and_back The second shininess argument must be a value between 0 0 and 1 0 see 3dlight By default both the front and back sides of a surface are visible In some cases back or front side of an object is never seen Faster rendering can be achieved for single sided drawings by defining which side is to be made visible The set_visibility method can be called to accomplish this The method call must be made before the call to begin_drawing define set_visibility as a method given 1 integer argument _front _back or _front_and_back Individual edges for surfaces specified by calls to draw_vertex are normally visible For some edges such as those on the interior of a complicated shape this visibility can lead to unwanted artifacts when the 3dgraphic is displayed The set_edge_visibility method can be used to hide or show future edges added to the shape by draw_vertex define set_edge_visibility as
78. essed click_count gt single click 2 gt double click key_code either _literal_key or a special key like _f6_key key_literal letter or number that was pressed modifiers presence of alt ctrl and or shift keys during event x y location of mouse click mouse move new canvas size pixels The id attribute contains an enumerated constant describing what type of event had occurred The following events are currently handled _activate window frame brought to front _close Tattempt to close window _key_down key pushed down key_code key_literal contain info _key_up key released key_code key_literal contain key info _mouse_down x y is click location in pixels _mouse_up x y is click location in pixels _mouse_move x y is new mouse location in pixels mouse_wheel_forward spin mouse wheel away from user mouse_wheel_back spin mouse wheel toward user _reposition uo _resize x y is new location of window in pixels x y is new size of window in pixels The user may choose to hold down the shift ctlr or alt key during the event This can be detected by examining the modifiers attribute for the presence of the _alt_mod ctrl_mod _shift_mod bits If an application needs to respond to selection by mouse of a visible 3dnode the 3dworld select_node method can be called to see if a node in the world has been clicked The 3dnode ob
79. ew the scene graph A light is also needed to illuminate the scene graph Cameras are implemented with the 3dcamera class while lights are represented by the 3dlight class Basically setting up each camera involves a Creating an instance of a 3dcamera object b Set the location and direction of the camera so that the scene graph will be in view by calling 3dcamera set_location and 3dcamera set_forward c Set the view angle aspect ratio and near and far clipping planes by calling 3dcamera set_perspective d Set the portion of the window canvas that the view from the camera should encompass by calling 3dcamera set_viewport e File the camera in the camera_set owned by the 3dworld that the camera is to see f Ifthe camera is to be part of the scene graph file it into the node_set owned by a parent 3dnode As an example the initialization code for the camera in the above example 2 is as follows create camera place it along positive z axis but point it down the negative z direction create camera call set_perspective camera 90 0 1 0 0 1 1000 0 1 call set_forward camera 0 0 0 0 1 0 call set_location camera 0 0 4 0 60 0 file this camera in camera_set world 3 1 Camera location and orientation Since the 3dcamera is derived from 3dnode it inherits the methods that allow orientation and position to be specified These methods are set_location x y zZ sets the lo
80. g enumerated constants _triangles Each successive group of 3 points defines a triangle _triangle_strip For each index n gt 2 a triangle is defined by points at n 2 n 1 and n in counter clockwise order Sometimes this is called the triangular mesh or just mesh _triangle_fan For each index n gt 2 a triangle is defined by points at n n 1 and 1 _quads Each successive group of 4 points defines a quadrilateral face _gquad_strip For each 2 indices n n 1 a new quadrilateral is composed of points at n 3 n 1 n n 2 in counter clockwise order _polygon The outline of the polygon is defined by points Again the points for front facing polygons should be arranged in a counter clockwise order The diagrams below show how the points array defines specifically formatted geometry 97 points l xl points 2 yl points 3 zl points 4 x2 points 5 y2 points 6 z2 points 7 x3 points 8 y3 points 9 z3 4 Counter clockwise rotation normals face Figure 1 3dgraphic _triangles format points l xl points 2 yl points 3 zl points 4 x2 points 5 y2 points 6 z2 points x3 points 8 y3 points 9 z3 Each successive point defines a new triangle Figure 2 the 3dgraphic _triangle_strip format 98 0 ut points 10 points 11 points 12 points 13 points 14 points 15 points 1l6 points 17
81. gle strip a quad strip can also be constructed Each two successive vertices will add a new quad using the two previous vertices for the face Each 2 successive points adds a new face draw_vertex x3 y3 z3 draw_vertex x5 y5 z5 drav_vertex x1 y1 z1 drav_vertex x7 y7 z7 drav_vertex x2 y2 z2 draw_vertex x8 y8 z8 draw_vertex x6 y6 z6 adrav_vertex x4 y4 z4 Figure 6 6 _guad_strip format A simple polygon can also be created The polygon must not have any concave portions or it may not be rendered correctly The outline of the polygon is defined by successive calls to draw_vertex Again the points for front facing polygons should be arranged in a counter clockwise ordering 49 Counter clockwise rotation normals face out draw_vertex x1 y1 z1 adraw_vertex x4 y4 z4 draw_vertex x2 y2 z2 draw_vertex x5 y5 z5 draw_vertex x3 y3 z3 Figure 6 7 _polygon format In the following example we will develop a new shape to represent a torus The code to construct this doughnut shaped object will be entered into the overridden draw method that is inherited from the 3dgraphic class The actual code to draw the torus will in a loop construct successive cylindrical rings that run in a circle along the shape of the torus A begin_drawing end_drawing block will construct each ring as a _quad_strip A normal vector is defined for each vertex This is computed as the vector originating from the center of th
82. h the model is to appear This must be done before the window is displayed Materials used in the model are automatically filed into the material_set owned by 3dmodel when the 3dmodel read method is called 44 6 Geometry Often times parts of a 3d scene cannot be stored in a 3ds or dxf 3dmodel file If it is the case that the geometry is not known exactly until runtime the programmer must write code required to construct this geometry SIMSCRIPT III provides several classes that allow this The 3dgraphic is the base class for all objects whose geometry is defined by program code and not by offline models stored in a file This class is derived from 3dnode and is part of the scene graph Since 3dgraphic is derived from 3dnode instances must be filed into a node_set owned by either the 3dworld or by another 3dnode attached to a 3dworld The 3d m and 3dshapes m subsystems provide several classes derived from 3dgraphic that can be useful for constructing various 3d objects see below Class name Description Geometry attributes 3dgraphic Can be used to draw any type of shape Override draw method draw_normal draw_texture_coordinate draw_vertex 3dfaces Tessellated surface triangles quads points normals attributes 3dlines Line segments in 3d space points width attributes 3dpoints Single points in 3d space points size attributes 3dtext 2d text in 3d space string width height fon
83. he view d A 3dlight can also be attached to a 3dnode allowing its position and orientation to be determined by the parent node If necessary file the light into a node_set 6 Create models if necessary a For each unique model that is used in the 3dworld create a instance of a 3dmodel object b If the model geometry is stored in a 3dStudio 3ds file a AutoCAD dxf file or a SIMGRAPHICS II sg2 file call the read method to read the file c File each 3dmodel instance in the model_set owned by the 3dworld 7 Create materials a Create an instance of a 3dmaterial object for each unique color or texture used in the program Materials defined offline in a 3ds file are created automatically when 3dmodel read is called b Set the color shininess and texture_name attributes c File each 3dmaterial instance into the material_set owned by 3dworld 8 Create other graphical objects for the simulation a Create instances of sub classes of 3dgraphic such as 3dfaces 3dlines 3dpoints to represent objects in the simulation Create instances of the subclasses of 3dgraphic described in step 1 b Create instances of 3dnode to represent a model on screen Assign the model attribute so that the 3dnode will draw this model at its location c Some objects may have a material attribute that needs to be assigned d File these instances into the node_set owned by the 3dworld
84. his torus in node_set world create a light from above set its color create light let diffuse_color light color rgb 0 8 0 8 0 call set_orientation light 0 0 1 0 0 0 1 file this light in light_set world call display window show every thing let timescale v 100 l second per 1 unit simulated time activate a animate window 10000 now start simulation end 52 _ Example 7 A torus Figure 6 9 Torus drawn using the _qguad_strip format 6 4 Surface appearance 3dgraphic has class methods that can be called to define the properties of the surface The set_color method can be used to set the color or if called before draw_vertex can set the color applied to individual vertices define set_color as a method given 1 integer argument front _back or _front_and_back 1 integer argument ambient _diffuse _specular 1 integer color argument color color rgb r g b The first argument indicates which side the color should be applied to and must be one of the constants _front _back or _front_and_back The second argument gives the type of lighting _ambient _diffuse or _specular that should reflect the given color see 3dlight The third argument is the color value obtained from the gui m color rgb class Attributes of the 3dmaterial object colors and texture can be applied to the 3dgraphic as well The set_material method should be called before begin_drawing and tak
85. hod given 1 integer argument line width in pixels define set_pen_pattern as a method given 1 integer argument line style These methods must be called before begin_drawing The current pen size is always in pixels The pattern is one of the following constants _ solid _long_dash _dotted _dash_dotted _medium_dash _dash_dot_dotted _short_dash _alternate See 3dlines for more The shininess of the surface used for specular lighting is set by calling the set_shininess class method define set_shininess as a method given 1 integer argument front _back or _front_and_back 1 double argument shininess 0 0 to 1 0 The first argument must be one of the constants _front _back or _front_and_back The second shininess argument must be a value between 0 0 and 1 0 see 3dlight By default both the front and back sides of a surface are visible In some cases back or front side of an object is never seen Faster rendering can be achieved for single sided drawings by defining which side is to be made visible The set_visibility method can be called to accomplish this The method call must be made before begin_drawing define set_visibility as a method given 1 integer argument _front _back or _front_and_back Individual edges for surfaces specified by calls to draw_vertex are normally visible For some edges such as those on the interior of a complicated shape this visibility can lead to unwanted artifact
86. ht_set world create model s create model of some people let enabled model 3dmodel _ smoothing 1 call read model people 3ds file this model in model_set world create objects used in the simulation create the_car let model the_car file this the_car model in node_set world Call the display method of the 3dwindow This will show the window call display window activate a animate window 10000 now let timescale v 100 start simulation end 8 3 Keyboard input Keyboard input can also be obtained by overriding the action method The event id s of interest are _key_up and __key_down When these ids are given the key_code attribute of 3devent will contain the predefined constant representing the key When key_code is set to the constant _literal_key the key_literal integer attribute must be used to get the code The key_literal attribute will contain the character code of the key that was pressed Essentially the key_code attribute is used to handle function arrow and other special keys while the key_literal attribute is used for the remaining alpha numeric keys 79 For example suppose the previous example was to be modified to use the keyboard instead of the mouse to move the camera In this case the action method would be changed to intercept keystrokes by comparing the 3devent s id attribute with _key_down The left right up and down keys could be u
87. ight object is located at 31 the top of each lamp post The variety attributes are assigned the 3dlight _positional value The cars are illuminated from different angles and from different light sources as they move through the lot which creates a realistic effect See Figure 4 2 5 SIMSCRIPT I Parking Lot O x Figure 4 2 Three positional lights used in the parking lot demo 4 2 Ambient Diffuse and Specular light When light strikes the surface of an object it is reflected based upon the properties of the surface material and on the normal vector of the surface in relation to the light s direction Surface normals can be specified along with the geometry of a shape and this is described later For now we will assume that the program will be using a 3dmodel that specifies the correct normal vectors for each surface For each 3dlight we can define how it interacts with the surface that is reflecting it Relative amounts of ambient diffuse and specular light can be specified by assigning the ambient_color diffuse_color and specular_color attributes These types of light are described below 32 Ambient This type of light is non directional and non positional location and orientation is ignored Ambient light will illuminate all surfaces ignoring normal vectors The ambient term is used simply to keep shadows from turning pitch black The relative intensity of ambient light can be set by assigning the ambient_color a
88. ill be modified The following flags are currently defined _visibility If this flag is zero the node will disappear the next time the window is updated Setting this to zero is useful to temporarily erase a node DEFAULT 1 _lighting If this flag is 1 lighting calculations will be used to shade this object When the flag is zero the node will be fully visible regardless of the position direction and intensity light sources Setting this flag to zero is useful for lines and text that are used to label or annotate a node during a simulation DEFAULT 0 For example to erase the node car the following code could be used Let enabled 3dnode _visibility 0 Another way to erase a node is to remove it from the node_set When removed the node will not be visible when the window s canvas is refreshed 3dpoints lineage 3dpoints gt 3dgraphic gt 3dnode The 3dpoints class is derived from 3dgraphic and represents a collection of simple dots in 3d space The points array attribute is 2 dim array containing the 3d coordinates The color attribute can be assigned a value returned from the gui m color rgb method and will apply to all points The size attribute controls the size in pixels of each dot The default size is 1 118 points 1l xl points 2 yl points 7 x3 points 3 zl g points s y3 oints 9 23 points 4 x2 ia p 9 points 5 y2 points 6 z2 Figure 16 3dpoints
89. ius yielding nx ny nz call draw_normal nx ny nz call draw_vertex x0 r yO r z call 3d m vector_normalize xl c yl c z minorRadius yielding nx ny nz call draw_normal nx ny nz call draw_vertex xl r yl r z loop 51 call end_drawing loop end main define window as a 3dwindow reference variable define world as a 3dworld reference variable define camera as a 3dcamera reference variable define light as a 3dlight reference variable define torus as a torus reference variable create the window create window let title window Example 7 A torus create the world create world file this world in world_set window create a camera 3 units out pointed at the origin create camera call set_perspective camera 60 0 1 0 0 1 100 0 1 call set_forward camera 0 0 0 0 1 0 call set_location camera 0 0 0 0 3 0 file this camera in camera_set world create our torus and set its size and detail parameters create a torus let minorRadius torus 3 let majorRadius torus 7 let numMinor torus 37 let numMajor torus 61 create a red material for torus s surface create a material torus let ambient_color material torus color rgb 0 2 0 0 0 0 let diffuse_color material torus color _red let specular_color material torus color _white let shininess material torus 1 0 file this material torus in material_set world save the torus in the world file t
90. ive to the owner node in the scene graph By default the forward vector is 0 0 0 0 1 0 which would point a node in the same direction as its owner node The up vector is the local y axis relative to the node s owner in the scene_graph By default this is 0 0 1 0 0 0 The local x axis is computed automatically by taking the cross product of these vectors Figure 2 2 Forward and Up vectors In this case the positive X axis would point away from the viewer The attributes forward_x forward_y forward_z up_x up_y and up_z can be used on the right but should not be assigned individually Both forward and up vectors must always be normalized and orthogonal to each other The set_orientation method allows both the forward and up vectors to be assigned For example set_orientation could be used to point a passenger in the opposite direction of the ferry Call set_orientation passenger 2 0 0 0 0 1 0 0 0 1 0 0 0 forward_x forward_y forward_z up_x up_y up_z Another method called set_forward allows the forward direction to be specified alone while the up vector is computed automatically This vector is computed in such a way that its projection onto the positive y axis is maximized for 3dcameras this will prevent the view from tilting assuming the floor of the scene lies in the x z plane define set_forward as a method given 3 double arguments forward_x forward_y forward_z Another
91. iven 1 text argument name of component searches the node_set for a component with the given name If the component is not found 0 is returned Suppose the application wanted to represent the turret sub component using an object derived from 3dnode instead of the 3dnode base class In this case the 3dmodel would be sub classed and its create_component method overridden define create_component as a virtual 3dnode reference method given 1 text argument name of the component 1 text argument name of required class This method is called during the execution of the read method to create a new sub node component The name given in the model file is provided in argument 1 By default this method will create a instance of the class named by argument 2 but can be overridden to 110 create a sub class of arg 2 Create_component is called automatically for each separate component that is created at the time a 3dmodel is read In the above example create_component would be implemented to create and return a turret object if the first argument specified the name assigned to the turret component in the graphics editor See below method tank_model create_component component_name class_name define my_turret as a turret reference variable if component_name Turret_for_tank if class_name lt gt 3dnode for safety check base class write as error 3dnode expected stop always create a
92. ject defines an action method that can be overridden by classes that 96 receive mouse clicks or other events An example of a user defined action method is shown below This method responds to shift clicks on a node owned by the_world Method my_3dwindow action event Define node as a 3dnode reference variable If id event 3devent _mouse_down and mouse click and f modifiers event 3devent _shift_mod lt gt 0 shift key down Let node select_node the_world x event y event If node lt gt 0 Call action node event pass event to 3dnode action Always Always End The 3devent instance will be destroyed after the 3dwindow action method is called 3dfaces lineage 3dfaces gt 3dgraphic gt 3dnode This class can be used to draw various segmented surfaces Each face must be planar but exists in 3d space Coordinate geometry is defined by a 1 dim double array attribute called points The points are assigned to the array with successive array elements assigned to x then y then z coordinate values for each point Le x1 yl zl x2 y2 z2 x3 y3 z3 The size of the array must therefore be three times the number of points npoints 3 A 1 dim real array attribute called normals can be assigned to specify a normal vector corresponding to each point The size of normals array must match the points array The format attribute can be assigned to one of the followin
93. ke tiles on a floor A large brick wall could be simulated using the 2d image of only a few bricks Of course if a texture is to replicated over a surface the edges of the image must be drawn so that the left edge will mate properly with the right edge 68 Figure 7 2 Top original texture Bottom seamless replication of 6 tiles The surface does not need to be flat In Figure 7 3 the surface of a sphere is texture mapped to look like the planet Jupiter 69 Figure 7 3 Bottom bmp file Jupiter bmp Top file applied to sphere The mapping of 3d geometry to 2d points in the image file is done using texture coordinates Basically when draw_texture_coordinate is called before draw_vertex the 2d texture coordinate is mapped or attached to the 3d vertex The result is a smooth texturing of the 2d image over the surface The texture_name attribute of 3dmaterial can be assigned the name of the file containing the image Currently only TARGA graphic tga files and Window Bitmap bmp files are supported JPEG files can be converted to BMP by a variety of windows programs The width and height of images should be a power of 2 for example 128 by 256 16 by 64 512 by 32 etc The 2d coordinates for a texture image range from 0 0 to 1 0 Coordinate are defined by an s axis and at axis The s axis is horizontal and the t axis is vertical with s 0 0 t 0 0 located at the lower left corner of the image and s 1 0 t 1 0
94. l e SIMSCRIPT III 3 D Graphics Reference Manual this manual is a detailed description of the SIMSCRIPT III 3 D graphical objects available in 3d m module e SIMSCRIPT III User s Manual A detailed description of the SIMSCRIPT III development environment usage of SIMSCRIPT II Compiler and the symbolic debugger from the SIMSCRIPT development studio Simstudio and from the Command line interface e SIMSCRIPT III Programming Manual A short description of the programming language and a set of programming examples e SIMSCRIPT III Reference Manual A complete description of the SIMSCRIPT III programming language constructs in alphabetic order Graphics constructs are described in the SIMSCRIPT III Graphics Manual Since SIMSCRIPT III is a superset of SIMSCRIPT II 5 a series of manuals and text books for SIMSCRIPT II 5 language Simulation Graphics Development environment Data Base connectivity Combined Discrete Continuous Simulation can be used for additional information e SIMSCRIPT II 5 Simulation Graphics User s Manual A detailed description of the presentation graphics and animation environment for SIMSCRIPT II 5 e SIMSCRIPT II 5 Data Base Connectivity SDBC User s Manual A description of the SIMSCRIPT II 5 API for Data Base connectivity using ODBC e SIMSCRIPT II 5 Operating System Interface A description of the SIMSCRIPT II 5 APIs for Operating System Services e Introduction to Combined Discre
95. l points 20 y7 points 3 zl points 21 z2 points 4 x2 points 22 x8 points 5 y2 points 23 y8 points 6 z2 points 24 z8 ss gliz gg points 10 x4 points 16 x6 points 1l y4 points 17 y6 points 12 z4 points 18 z6 I Figure 5 3dgraphic _quad_strip format Counter clockwise rotation normals face out points l xl points 2 yl points 3 zl points 13 xs points 12 y5 points 4 x2 points 15 2z5 points 5 y2 ints 6 z2 points 6 z points 10 x4 points 1ll y4 ints 7 x3 points 7 x points 12 z4 points 3 y3 points 9 z3 Figure 6 3dgraphic _polygon format The material attribute of 3dfaces can be set to a 3dmaterial instance The material colors will be applied to each face The texture_points real array attribute will be utilized if the texture_name attribute of the material has been specified See the reference for the 3dMaterial class for a description of supported texture mapping functions The edge_flags array attribute of 3dfaces can be assigned to a 1 dim integer array sized to match the points array Each element value defines the visibility of the corresponding face edge with a non zero value meaning visible If the array is not assigned all edges are visible 100 In some cases a performance improvement can be gained by using indexed vertex arrays If vertices are naturally shared in the geometry
96. le text string Bitmapped fonts Characters in a bitmapped or raster based font are basically small 2d bitmap images that are copied to the screen when the text is rendered Text drawn using these types of fonts will always appear right side up regardless of how the 3dtext object or its owner node is oriented However the 3dnode location properties is still utilized In other words the text can be positioned by calling the set_location method Bitmapped text will appear the same size regardless of its distance from the camera If a larger or smaller text size is needed a different font must be assigned to the font attribute 3dtext 9 by_15_ font 3dtext 8_by_13_font fixed width bitmap font fixed width bitmap font 3dtext times_roman_10_font variable width bitmap font 3dtext times_roman_24_font variable width bitmap font 3dtext helvetica_10_font variable width bitmap font 3dtext helvetica_12_font variable width bitmap font 3dtext helvetica_18_font variable width bitmap font For bitmapped fonts the align_horiz align_vert attribute allows the text to be centered or left right top bottom justified The following constants can be assigned to the alignment attribute define _left_justified 0 _centered _right_justified as constants for the aligh_horiz attribute define _bottom 0 _middle _top _bottom_cell _top_cell as constants for the align_vert attribute _center
97. ll set_forward camera 0 0 0 0 1 0 file this camera in camera_set world 3 3 Adding a 3dcamera to the scene graph Since the 3dcamera object is derived from 3dnode it can optionally be part of the scene graph If a camera is filed into the node_set owned by a parent node it will move and rotate with the parent automatically If for example you wanted to see the view out of the locomotive of a moving train the 3dcamera object could be filed into the node_set of the locomotive s 3dnode The camera would then be located and oriented with respect to 25 the locomotive and not the ground This would naturally show the view from the train as it moves and turns along its track Suppose we wanted to modify Example 2 to show the view from the tanks perspective instead of a static view from the parking lot Adding the following code after the tank is created could do this file camera in node_set the_tank call set_location camera 0 0 4 0 0 0 location relative to tank s center call set_forward camera 0 0 0 0 1 0 point camera in same dir as tank Example 3 contains the code to do this 3 4 Viewports and multiple cameras By default the view seen by each camera will encompass the entire canvas of the window to which it is attached However the set_viewport method may be called to assign a rectangular box to which the view is mapped define set_viewport as a method given 2 integer arguments x y in pixels
98. m the color rgb class method which is found in the gui m subsystem The color rgb class function takes three double parameters as the percentage of RED GREEN and BLUE in the color all in the range 0 1 Predefined colors are defined in the color class also For example to set specular color to a particular shade of yellow Let specular_color my_light color rgb 0 9 0 9 0 0 Or to set specular color to red Let specular_color my_light color _red The witnesses effect of the light striking a 3d object and reflecting into the camera depends on the ambient diffuse and specular colors attributes of not only the 3dlight but also of the 3dmaterial which represents the surface properties of the object and is described later If specular shiny effects are to be seen usually both the material and light must have a high degree of specular color Figure 4 3 shows how specular light can 33 affect the appearance of a surface The scene is illuminated with a directional light from above I e set_forward 0 0 1 0 0 0 and with the specular_color attribute of the 3dlight set to color _white As far as the toruses go the ambient and diffuse color for all is set to a shade of purple or color rgb 0 8 0 4 0 7 However the specular_color attribute for toruses on the right is greater that those on the left 3 Toruses Use the arrow keys to move the light 2 x Figure 4 3 Objects on the left have more specular color and
99. mera call set_forward the_camera 0 0 0 0 1 0 call set_location the_camera 0 0 0 5 1 5 end call set_perspective the_camera 60 0 1 0 1 0 10 0 1 file the_camera in camera_set the_world create light s create light call set_location light 0 0 500 0 500 0 file this light in light_set the_world create model s of some people create model let enabled model 3dmodel _ smoothing 1 call read model people 3ds file this model in model_set the_world create objects used in the simulation the load method must be used for hierarchical selection to work create the_peopl call load the_people model file this the_people in node_set the_world create a text messag create the_messag let font the_message 3dtext 9_by_15_font let string the_message Click on the people call set_location the_message 0 25 0 25 0 0 file the_message in node_set the_world Call the display method of the 3dwindow This will show the window call display window activate a animate window 10000 now let timescale v 100 start simulation 82 Test of 3d component selection o E Selected node named Figure 8 2 Clicking on the lady s handbag 83 9 Animation and Simulation Animating a 3d scene graph comes naturally when running a simulation Objects being simulated are usually moving or somehow changing shape over time
100. n 3 double arguments target_x target_y target_z sets the forward orientation such that the node points at the target point The target points should be given in global world coordinates The set_orientation and set_forward methods expect vectors that are oriented with respect to the node s owner in the scene graph or the 3dworld if the 3dnode is filed in 3dworld node_set Likewise the set_location method provides coordinates with respect to the coordinate system defined by node s owner in the scene graph However in some cases it may be easier to position the node with respect to its own coordinate system The move method will shift the position of a node by a movement right up and forward with respect to its own axes The node s location will be moved along its local x axis y axis and z axis by the three given values define move as a method given 3 double arguments dx dy dz right up forward It is also possible to spin a 3dnode on one of its three local axes The rotate_x rotate_y and rotate_z methods will do just that Each method takes an angle in degrees as an argument and spins the 3dnode by that amount about the local not owner axis These methods are similar to the move method in that they take delta values instead of absolute values For example if an airplane is pointed forward along its positive z axis call the rotate_x method will pitch up or down In this case the local Y and Z axe
101. n t forget to set timescale v activate a animate window 10000 now let timescale v 100 start simulation 11 5 Use the arrow home and end keys to move the model Sy x Figure 1 1 Example 3d graphics program showing a 3d model of a 1963 ford 1 3 Class hierarchy There are many classes that can be used to implement 3d graphics the full hierarchy for the ones found in the 3d m subsystem is shown in Figure 1 2 Figure 1 3 shows classes found in 3dshapes m 12 Figure 1 2 3d m classes 3dRectangle Figure 1 3 3dshapes m classes 13 2 The scene graph To write a SIMSCRIPT 3d graphics program you must make use of windows worlds and nodes The nodes are used to compose the hierarchy of the scene graph Every 3d graphics program must construct at least one scene graph to represent the 3d objects and background Each node in this graph is represented with an instance of a 3dnode object The 3dnode object is filed into a node_set which is owned by another parent 3dnode 2 1 The 3dworld The root of a scene graph must always be an instance of a 3dworld object The 3dworld class also owns a node_set for child nodes to be filed into Every 3dworld instance is filed into a world_set owned by a 3dwindow object The 3dwindow object represents GUI window and can be moved and resized like other windows on the computer screen It can contain multiple 3dworlds and ac
102. n_rate 0 move the tank forward let speed _forward_speed wait abs f forward speed units let speed 0 0 loop close unit 1 end our motion method will be called automatically as simulation time Tadvances method tank motion dt call 3dnode motion dt call rotate_y dt spin_rate call move 0 0 0 0 dt speed end main define world as a 3dworld reference variable define camera as a 3dcamera reference variable define light as a 3dlight reference variable define tank_model cone_model as a 3dmodel reference variable define background as 3dnode reference variables define the_tank as a tank reference variable define cones as a 2 dim 3dnode reference variable define _num_rows_cones 11 _num_cols_cones 11 as a constant define i j as an integer variable create the window create window let title window Example 2 using a simple 3dnode scene graph create the world create world file this world in world_set window create camera place it along positive z axis but 19 end point it down the negative z direction create camera call set_perspective camera 90 0 1 0 5 0 115 0 1 call set_forward camera 0 0 0 0 1 0 call set_location camera 0 0 4 0 60 0 file this camera in camera_set world create a light source and point it in the same direction as the camera create light call set_forward light 0 0 0 0 1 0 file this light in light_set world creat
103. nd spot properties Ambient This type of light is non directional and non positional location and orientation is ignored Ambient light will illuminate all surfaces ignoring normal vectors The ambient term is used simply to keep shadows from turning pitch black The relative intensity of ambient light can be set by assigning the ambient_color attribute to an rgb value returned from the gui m color rgb class method If less ambient light is required darker colors should be used For example setting ambient_color to color rgb 0 25 0 25 0 25 will provide a 1 4 intensity of ambient light Diffuse Diffuse light is reflected from a surface in all directions The amount of reflected light is determined by the diffuse color of surface material see 3dmaterial Rough surfaces should have a relatively bright diffuse_color attribute Both diffuse and specular light allows objects to be shaded based on surface normal vectors Surface elements with normals pointing at the light source will be illuminated while surfaces with normals orthogonal to the light source s direction will not The diffuse_color attribute determines the color and intensity of diffuse light Specular Specular light is reflected from a surface in mostly one direction Shiny surfaces reflect more of the specular light than rough surfaces The amount of reflected light is determined by the specular color of surface material see 3dmaterial Surface element
104. nd can be used to show a simple text string within the scene graph The string attribute must be assigned to the desired text The text can be colored and there are several fonts to choose from Currently only predefined fonts are available as class attribute pointers that can be assigned to the font attribute These fonts are automatically initialized before the SIMSCRIPT program is run The choice of font affects not only the appearance of the text but also its behavior Both raster and vector fonts can be used Vector fonts A vector font is rendered by drawing a series of line segments in 3 dimensions Vector text follows the same rules as do other 3dgraphic shapes with regard to location and orientation The advantage of using this type of text is that it is part of the object for example the text on a road sign or the monogram on the side of an airplane The text will increase in size as the camera moves closer to it The disadvantage is that the text is usually composed of thin lines and may not look good when it is sized big The following vector fonts are available 120 3dtext stroke_font Variable width vector font 3dtext stroke_mono_font Fixed width vector font The size of vector text is controlled by its width and height attributes These attributes function the same as the width and height for the 3drectangle class do The height defines the maximum height including descenders and the width applies to the who
105. nd n in counter clockwise order Sometimes this is called the triangular mesh or just mesh _triangle_fan For each index n gt 2 a triangle is defined by vertex at n n 1 and 1 _quads Each successive group of 4 vertices defines a quadrilateral face _gquad_strip 102 For each 2 indices n n 1 a new quadrilateral is composed of vertices at n 3 n 1 n n 2 in counter clockwise order _polygon The outline of the polygon is defined by vertices Again the vertices for front facing polygons should be arranged in a counter clockwise order The draw_normal class method can be called to specify a normal vector to be applied to all subsequent vertices X y z components are specified and the given vector should be normalized to the range 0 0 1 0 define draw_normal as a method given 3 double arguments x y z The draw_texture_coordinate method can be called to map the next vertex to a given 2d texture coordinate These texture coordinates reference the texture of the current material see 3dgraphic set_material The texture is a bitmapped image with the 0 0 0 0 coordinate in the lower left corner and 1 0 1 0 in the upper right These two s and t coordinates are the given arguments to the method define draw_texture_coordinate as a method given 2 double arguments s t The draw_vertex class method adds a new 3d vertex to the current drawing given the x y and z components define
106. nd tank to be seen To avoid distorting the aspect ratio we will pass 1 to the Pperspective_autosize argument call set_perspective camera 90 0 1 0 5 0 115 0 1 24 The use of the set_orthographic method is not common When viewing an orthographic projection there is no depth information provided In other words an object that is far away from the camera will be rendered to be the same size as when it is close to the camera The arguments to set_orthographic define the clipping volume or the coordinate boundaries of the box that encloses everything that we want to view These units are relative to the location of the camera define set_orthographic as a method given 2 double arguments left right 2 double arguments bottom top 2 double arguments far near 1 integer argument l gt adjust size automatically after window resize ortho_yhi viewpoint viewing volume ortho_ylo ortho_zlo ortho_zhi Figure 3 3 Using the set_orthographic method It would be possible to modify Example 2 to use an orthographic transformation The call to set_perspective is replaced with a call to the set_orthographic method To simplify things we will place the camera in the center of the parking lot and allow it to see 50 meters to its left its right its front and its back create camera call set_orthographic camera 50 50 0 100 50 50 1 call set_location camera 0 0 0 0 0 0 ca
107. ned by a 1 dim double array attribute called points Vertex data is packed into the points array as x y1 z1 x2 y2 z2 x3 y3 23 The format attribute can be assigned to one of the following enumerated constants LLES Each successive group of 2 points defines a separate line segment see Figure 8 _line_strip Successive points are connected by line segments The first and last points are not connected see Figure 8 _line_loop Successive points are connected by line segments The first and last points are connected see Figure 9 The diagrams below show how the points array defines specifically formatted geometry 106 points 1 points 2 points 3 lez sl points 4 points 5 points 6 zs l points 7 points 8 points 9 ls el Hy points 10 iyl points 11 lig points 12 E T points 13 liy2 points 14 a 4 points 15 ma points 16 1y3 points 17 1123 points 18 Figure 8 3dgraphic _lines format points 1 points 2 points 3 points 4 points 5 points 6 points 7 points 8 points 9 gi points 10 kiyi points 11 izl points 12 PER points 16 tye points 17 LZA points 18 msg points 13 11y3 points 14 bigs points 15 Figure 9 3dgraphic _line_strip format points 1 points 2 points 3 points 4 points 5 points 6 points 7 points 8 points 9 hig points
108. node A scaling factor is provided for each axis and as with move and rotate scaling is performed along the local axes Each axis is scaled by the given scale factor a value of 1 0 will not change the axis Consider a process method to simulate an animated explosion The scale method is called in a loop to animate the size change of the explosion The wait statement allows a small amount of time to elapse Process method explosion explode define I as a integer variable for i 1 t 100 do call scale 1 1 1 1 1 1 sx sy sz width height depth wait 0 1 units loop end 2 5 Complete Scene graph example In the following example a scene graph will be created showing some traffic cones and a tank The tank will maneuver through the cones as the simulation runs Preamble including the 3d m 3dshapes m subsystem begin class tank every tank is a 3dnode and has 18 a speed a spin_rate a movement process method overrides the motion define speed spin_rate as double variables end define window as a 3dwindow reference variable end process method tank movement define spin forward as double variables define _spin_speed 20 _forward_speed 2 as constants open unit 1 for input name is example2 dat use unit 1 for input let eof v 1 while eof v 1 and visible window lt gt 0 do read spin forward rotate the tank let spin_rate _spin_speed sign f spin wait abs f spin _spin_speed units let spi
109. nt if id event 3devent _mouse_down 125 for each world in world_set do try to pick a node in this world given click location let node select_node world x event y event if node lt gt 0 perform action on selection of node call action node event always loop if node 0 perform some sort of action on background click always always end If two or more 3dworld objects are filed in the same 3dwindow world_set instances filed last will overlap the instances filed first In other words all graphics filed in the latter 3dworld will appear on top of all graphics filed in the previous worlds The 3d coordinates specified by the 3dnode set_location method as well as 3d vertices points are specified relative to the owner 3dnode of the object To find the location in global coordinates i e the system used to position nodes filed directly in the 3dworld node_set the get_location method can be called A reference to the 3dnode instance is the first argument and the global x y z location is yielded define get_location as a method given 1 3dnode reference argument descendant node yielding 3 double arguments x y z in global coordinates 126
110. on method are described in the tables below Left right or middle mouse button down click in canvas 3devent attribute Value id 3devent _mouse_down X Y Location in pixels of click from top left corner of canvas button_number 1 left button 2 middle button 3 right button click_count 1 single click 2 double click modifiers shift_mod _alt_mod and or _ctrl_moddepending on which key is held down during the click Mouse movement in canvas 3devent attribute Value 76 id 3devent _mouse_move X Y Location in pixels of current pointer location from top left corner of canvas Left right or middle mouse button release in canvas 3devent attribute Value id 3devent _mouse_up X Y Location in pixels of mouse from top left corner of canvas button_number 1 left button 2 middle button 3 right button modifiers shift_mod _alt_mod and or _ctrl_moddepending on which key is held down during the click Mouse wheel rolled forward 3devent attribute Value id 3devent _mouse_wheel_forward x y Location in pixels of mouse from top left corner of canvas button_number Usually 2 to indicate the middle button modifiers shift_mod _alt_mod and or _ctrl_mod depending on which key is held down during the wheel movement Mouse wheel rolled backward 3devent attribute Value id 3devent _m
111. or by another 3dnode 9 Call the display method of the 3dwindow This will show the window 10 Before starting the simulation activate the 3dwindow animate method This method will keep refreshing the window as often as possible as the simulation runs Don t forget to set timescale v 1 2 Example code for a typical 3d graphics program Example of a initializing a 3d graphics application Requires ford 3ds model file preamble including the 3d m subsystems begin class my_window every my_window is a 3dwindow and overrides the action end define the_car as a 3dnode reference variable end 2 Write event handling code overriding the 3dwindow action method method my_window action event if id event 3devent close stop always if id event 3devent _key_down select case key_code event case 3devent _right_key call rotate_y the_car 2 case 3devent _left_key call rotate_y the_car 2 case 3devent _up_key call rotate_x the_car 2 case 3devent _down_key call rotate_x the_car 2 case 3devent _home_key call move the_car 0 0 0 0 5 0 case 3devent _end_key call move the_car 0 0 0 0 5 0 default endselect always return with 0 end main define window as a my_window reference variable define world as a 3dworld reference variable define camera as a 3dcamera reference variable define light as a 3dlight reference variable define model as a
112. orward cos f flight_angle pi c 2 0 0 0 sin f flight_angletpi c 2 0 end elevation We call this method from sky_window action if a jet is clicked on method moving_jet action event let event event let string the_message name was clicked on 89 call update_drawing the_message 3dgraphic _once return with 0 end overriding the window s action methods lets us to get mouse clicks user pushes the mouse button call the select_node method to see if a plane was clicked on method sky_window action event define node as a 3dnode reference variable STE CA if id event let nod if node lt gt 0 call action node event else let string the_message Click on a plane call update_drawing the_message 3dgraphic _once always always return end main define define define define reserve names 3devent _mouse_down select_node the_world x event y event with 0 _num_planes 10 as a constant i as an integer variable plane as a moving_jet reference variable names as a 1 dim text array as _num_planes let names 1 Bobcat let names 2 Prince let names 3 Mercury let names 4 Jumper let names 5 Cowboy let names 6 Flash let names 7 Joker let names 8 Tceman let names 9 Reddog let names 10 Ace create the window create the_window let title the_window let color the_window Simulation and 3
113. ouse_wheel_back X Y Location in pixels of mouse from top left corner of canvas button_number Usually 2 to indicate the middle button modifiers shift_mod _alt_mod and or _ctrl_mod depending on which key is held down during the wheel movement In the following example we will modify the Examplel program to receive mouse movement The program will show the model of a car but allow the user to change the orientation of the camera by clicking and dragging the mouse Dragging the mouse left will rotate the camera counter clockwise and dragging right will rotate clockwise Dragging up will rotate up and dragging down will rotate the camera down A zoom function is easily implemented by changing the perspective on the camera Zooming in is accomplished by narrowing the depth of field view via the set_perspective method of the 3dcamera object Zooming out can be done by widening depth of field The mouse wheel is a natural tool for performing a zoom Rolling the wheel forward should zoom in while rolling it backwards zooms out The program will define a sub class of 3dwindow called my_window and override the action method Inside action the id attribute of the given 3devent instance is compared with one of the following constants _mouse_up _mouse_down _mouse_move mouse_wheel_forward or _mouse_wheel_back When the mouse is clicked down the location is saved and a flag is set to indicate that dragging is on When the mou
114. owned by the 3dnode The find method can then be used to get a reference to nodes named in the model The copy_attributes method is automatically invoked for the sub nodes when the load method is called If application defined sub classes of 3dnode are contained in the model s node_set copy_attributes should be overridden to ensure that all new fields are duplicated Another way to define the shape of a node is by assigning its model attribute During initialization an instance of a 3dmodel object can be assigned to the model attribute of the 3dnode The image of the model can then be located and oriented by calling methods 117 such as set_location and set_orientation Multiple 3dnode objects can reference the same 3dmodel as long as all the objects are attached to the same 3dworld define model as a 3dmodel reference variable monitored on the left references the model for drawing this node Options that control how a 3dnode is displayed can be set via the enabled attribute Although this attribute is defined as a method it can be used on the left and right and takes an integer identifier as its argument define enabled as an integer method given l integer argument drawing aspect to enable or disable enables or disables a drawing attribute To disable assign 0 To enable assign 1 Pass one of the constants _lighting _visibility method behaves recursively drawing attributes of all sub nodes w
115. phic 0 0 0 5 0 0 create a camera to show the scen use default attributes create camera call set_location camera 0 0 0 75 1 5 file this camera in camera_set world call aim camera 0 0 0 0 0 0 show the window call display window while visible window lt gt 0 call handle 3devents r end 61 a Example 9 A spiral of points oo es C Figure 6 16 Example 9 output 6 8 Text There are many uses for graphic text in a simulation For example state information may need to be displayed for an object being simulated Or maybe the object needs to be tagged with a unique text string so that it can be identified Of course its possible that text is part of the and object being simulated like a traffic sign SIMSCRIPT HI 3d graphics allows both scalable and non scalable text to be display in a 3dworld The class used for text display is called 3detext and is derived from the 3dgraphic class The 3dtext class can be used to show a simple 1 line or multi line text string within the scene graph Currently only predefined fonts are available as class attribute pointers that can be assigned to the font attribute These fonts are automatically initialized before the SIMSCRIPT program is run The choice of font affects not only the appearance of the text but also its behavior The application may require the text to act like part of the scene in other words to obey the same rules
116. phical object around in a simulation Requires ford 3ds model file preamble including the 3d m subsystems end main define window as a 3dwindow reference variable define world as a 3dworld reference variable define camera as a 3dcamera reference variable define light as a 3dlight reference variable define model as a 3dmodel reference variable define the_car as a car reference variable create window let title window Move a car across the screen create world file this world in world_set window create camera call set_orientation camera 0 0 0 0 1 0 0 0 1 0 0 0 call set_location camera 0 0 0 0 25 0 file this camera in camera_set world create light call set_location light 0 0 500 0 500 0 file this light in light_set world create model call read model ford 3ds file this model in model_set world 86 create the_car let model the_car model call set_forward the_car 1 0 0 0 0 0 file this the_car in node_set world call display window activate the move_to method file the_car in motion_set Cali s et _ilocation the car 20 0 0 0 0 0 activate a move_to the_car 20 0 0 0 0 0 10 0 now destination speed activate a animate window 0 now let timescale v 100 real seconds simulated seconds start simulation end 9 5 Achieving customized motion Linear motion is not always adequate The specific needs of the program to rotate scale or
117. ple 1 we load the model of the 3d car from the file named ford 3ds as follows define model as a 3dmodel reference variable create model call read model ford 3ds file this model in model_set world 5 2 Linking a 3dmodel instance to a 3dnode instance 37 The 3dmodel class is not derived from 3dnode and therefore cannot be shown in a window directly The 3dmodel instance can be assigned to the model attribute of a 3dnode This will provide a link from the image of the 3dmodel to the 3dnode Many instances of 3dnode can reference the same 3dmodel instance This scheme allows a single model to be drawn in different locations and orientations in the world See Figure 5 1 3dworld node set 3dnode 3dnode 3dnode model 3dmodel attribute Figure 5 1 Three 3dnode instances using the same model of a jet 5 4 Copying the scene graph of a 3dmodel In some cases the application may require individual images of a 3dmodel to appear differently In this case the same model cannot be shared each image is different and requires its own separate scene graph For example if many tanks were to be displayed each turret will have a different orientation In this case instead of assigning the model attribute the 3dnode load method would be called This method will make copies of each sub component and place the nodes into the appropriate node_set Define tankl tank2 as tank reference variables
118. r variable monitored on the left One of the constants 3dmaterial _front 3dmaterial _back or _3dmaterial _front_and_back can be assigned to the visibility attribute _front_and_back is the default value The _front side is defined by a counterclockwise winding of the vertices The right hand thumb rule can be used as mnemonic reminder If a fist is made with the right hand and the vertices of a polygon are ordered in the direction the fingers point then the thumb points out from the front of the surface A caveat to using the 3dmaterial object is that each instance must be filed in a material_set before it is rendered 3dmaterials should be filed into the set owned by the 3dworld in which it will be visible The 3dmodel also owns a material_set containing materials to be used within the model 109 3dmodel The 3d surfaces and geometry shown in the 3dworld can be defined in one of two ways The 3dgraphic and its subclasses allow the application to specify the geometry and materials and runtime The 3dmodel class allows the surfaces and materials to be loaded from a file Basically a single instance of a 3dmodel is created for each separate 3d file The read method loads the contents of the file creating surfaces and materials which are saved in memory define read as a method given 1 text argument file name including 3ds dxf sg2 extension 1 text argument name of model in the file sg2 files only The first a
119. rgument specifies the name of the file Currently the file must be in either autodesk 3dStudio or 3ds format the extension is required AutoCAD dxf format or SIMGRAPHICS II sg2 format For sg2 files the name of the model within the file is provided in the second argument The 3dmodel class is not derived from 3dnode and therefore cannot be shown in a window directly The 3dmodel can be assigned to the model attribute of a 3dnode This will provide a link from the image of the 3dmodel to the 3dnode Many instances of 3dnode can reference the same 3dmodel instance This scheme allows a single model to be drawn in different locations and orientations in the world Models may be designed in the 3d editor to have well defined components For example a tank model may have a turret component that can be rotated with respect to the tank The turret sub component may in turn have a gun sub component The application may need access to these sub components at runtime i e rotate the turret move the gun in and out when it fires etc If sub components like this are defined in the graphics editor they will be preserved when model is loaded in the application The node_set owned by the 3dmodel will contain these components The find method can be called to perform a depth first search for a sub component provided that the component has been given a name in the graphics editor define find as a 3dnode reference method g
120. ription started by begin_drawing We will refer to this as a drawing block There can be multiple drawing blocks defined in a single draw method It is also possible to sub class the 3dgraphic and override the draw method to add geometry Nested drawing blocks are not allowed and will be flagged as a runtime error There are several formats of geometry that can be specified in a drawing block A format argument is passed to the begin_drawing method The 3dgraphic class provides to following predefined constants that can be passed to begin_drawing The formats are described in detail later Constant Format of Geometry points Draw dots in 3d space Each call to draw_vertex adds a dot lines Each 2 successive vertices defines a line segment line_loop Each vertex is connected to the next with the first connected to last line_strip Each vertex is connected to the next triangles Each successive group of 3 vertices defines a triangle triangle_strip For each index n gt 2 a triangle is defined by vertex at n 2 n 1 and n in counter clockwise order Sometimes this is called the triangular mesh or just mesh _triangle_fan For each index n gt 2 a triangle is defined by vertex at n n 1 and 1 quads Each successive group of 4 vertices defines a quadrilateral face quad_strip For each 2 indices n n 1 a new quadrilateral is composed of vertices at n 3 n
121. s A Model represents a specific shape that can be displayed multiple times in the same window at different locations and orientations Methods of this class allow geometry and properties for various surfaces and lines to be specified Graphic items are attached to the scene graph that reference model objects Models are implemented with the 3dmodel class A Material provides a covering of 3d surfaces The material can have a distinct color and shininess Texture mapping is supported via the material object The texture is stored in a 2d raster image file such as a Windows Bitmap or BMP file or a Targa Graphics file TGA 2d Coordinates specified with the 3d vertices identify the position in the raster image file that is to map to the surface Surface materials are implemented with the 3dmaterial class A Graphic is a node in the scene graph that provides the base class for all visible 3d objects whose geometry is defined at runtime Sub classes of the graphic object are provided that support various types of lines and surfaces The graphic object can also be sub classed and its draw method overridden This allows customized surface types to be created and rendered by the application The graphic is implemented with the 3dgraphic class The World is used as the root of the scene graph Several worlds can appear in the same window allowing such things as control panels graphs heads up displa
122. s and airplanes by program code can be a long process For this reason it is much easier to load predefined objects from a graphics file format such as Autodesk s 3ds These 3d graphics can be created using a 3d point and click editor or can be purchased online In any case SIMSCRIPT 3d graphics supports the loading of two well known 3d graphics file formats 3ds and dxf 5 1 Reading in the 3dmodel from a file The 3d surfaces and geometry shown in the 3dworld can be defined in one of two ways The 3dgraphic and its subclasses allow the application to specify the geometry and materials and runtime The 3dmodel class allows the surfaces and materials to be loaded from a file Basically a single instance of a 3dmodel is created for each separate 3d file The read method loads the contents of the file creating surfaces and materials which are saved in memory define read as a method given 1 text argument file name including 3ds dxf sg2 extension 1 text argument name of model in the file sg2 files only The first argument specifies the name of the file Currently the file must be in either autodesk 3dStudio or 3ds format the extension is required AutoCAD dxf format or SIMGRAPHICS II sg2 format For sg2 files the name of the model within the file is provided in the second argument Also each 3dmodel instance must be filed into a model_set owned by the 3dworld which will show the model From Exam
123. s define set_orientation as a method given 3 double arguments forward_x forward_y forward_z 3 double arguments up_x Up y up_z Another method called set_forward allows the forward direction to be specified alone while the up vector is computed automatically This vector is computed in such a way that its projection onto the positive y axis is maximized for 3dcameras this will prevent the view from tilting assuming the floor of the scene lies in the x z plane define set_forward as a method given 3 double arguments forward_x forward_y forward_z 114 Another method that may be useful for setting the orientation of a 3dnode is the aim method Calling the aim method will set the forward direction of the node so that it points at a given location The location should be in global coordinates non local to the 3dnode The 3dworld get_location method can be used to convert a location from local to global coordinates When aim is used on a sub component the local orientation forward and up vectors of the sub component will be modified so that the sub component points with its positive z axis at the given location The aim method can only be called after the 3dnode has been filed into the node_set Since the aim method uses the orientation and location of parent nodes it should be called after all the location of all parent grand parent etc nodes have been initialized define aim as a method give
124. s are rotated but the X axis will remain unchanged Calling the rotate_y method will yaw about its y axis Calling the rotate_z method will roll the airplane define rotate_x rotate_y rotate_z as method given 1 double argument angle in degrees The local axes of a node are rotated with the node itself For example in Figure 10 a box is first rotated about the z axis the moved by 100 0 units in the Y direction up 115 Y Z 2 2 gt ye X ake a call move 0 100 0 Figure 15 Calling rotate_z followed by move The scale method will modify size of the node A scaling factor is provided for each axis and as with move and rotate scaling is performed along the local axes Each axis is scaled by the given scale factor a value of 1 0 will not change the axis define scale as a method given 3 double arguments sx sy sz width height depth In cases where a 3dnode must be located in the hierarchy the find method can be used This method takes a single text argument and matches it to the name attribute of one of the descendants First the node_set is searched If a match is not found the find method is called recursively for each node in the set 0 is returned if no match is found define name as a text variable define find as a 3dnode reference method given 1 text argument Simulation is integrated into the 3dnode by allowing instance to move over simulation time After the 3dwindow anima
125. s location and orientation The location_x location_y and location_y attributes represent the x y and z coordinates of the node s position with 113 respect to its owner node in the scene graph Right handed use of these attributes is allowed but the set_location method should be used to set these attributes define location_x location_y location_z as double methods define set_location as a method given 3 double arguments EUS VG 2 The orientation is defined by 2 vectors forward and up See Figure 14 The forward vector indicated the direction of the local z axis relative to the owner node in the scene graph By default the forward vector is 0 0 0 0 1 0 which would point a node in the same direction as its owner node The up vector is the local y axis relative to the node s owner in the scene_graph By default this is 0 0 1 0 0 0 The local x axis is computed automatically by taking the cross product of these vectors Figure 14 Forward and Up vectors In this case the positive X axis would point away from the viewer The attributes forward_x forward_y forward_z up_x up_y and up_z can be used on the right Both vectors must always be normalized and orthogonal to each other so they should be assigned at the same time The set_orientation method allows both the forward and up vectors to be updated define forward_x forward_y forward_z as double methods define up_x up_y up_z as double method
126. s when the 3dgraphic is displayed The set_edge_visibility method can be used to hide or show future edges added to the shape by draw_vertex define set_edge_visibility as a method given 1 integer boolean argument Q gt invisible 1 gt visible specifies visibility of future edges of a face By default the draw method is only called once by the system when the 3dgraphic first appears If the geometry or surface has changed the update_drawing method must be used to indicate that the 3dgraphic is old and that the draw method should be invoked the draw method should never be called directly define update_drawing as a method given 104 1 integer argument always _once _never never Draw will not be called Graphic will effectively be hidden from view once Draw called the next time the window is refreshed The image of the 3dgraphic will be cached for future refreshes of the screen The update_drawing method must be called for draw to be invoked again _always Draw will be called each time the canvas is refreshed This is useful for objects with constantly changing geometry 3dlight lineage 3dlight gt 3dnode A 3dlight object represents a light source in 3d space It is derived from 3dnode and inherits its location orientation and set properties Light sources are apparent only if the lighting attribute of the 3dworld is non zero A single light source can have ambient diffuse a
127. s with normals pointing at the light source will be illuminated while surfaces with normals orthogonal to the light source s direction will not The specular_color attribute determines the color and intensity of this light 105 The variety attribute defines the type of lighting One of the following constants can be assigned _positional Light emanates in all directions from a single position This position is the location attribute inherited from 3dnode _directional Light travels in only a single direction which is determined by the forward vector inherited form 3dnode The location attribute is ignored _spot Spot lighting is both positional and directional The location attribute determines spot light position while orientation i e the forward vector inherited from 3dnode determines its direction The intensity of spot lighting is concentrated along the forward vector s direction The spot_cutoff attribute is an angle in degrees that indicates how the light fans out from its source location The default value is 45 degrees The spot_cutoff attribute specifies the radial angle in degrees of the cone of light emanating from a spot variety light The angle is specified from the center line to the edge of the cone This attribute must range from 0 to 90 3dlines lineage 3dlines gt 3dgraphic gt 3dnode This class derived from 3dgraphic can be used to draw various segmented lines Coordinate geometry is defi
128. se is 71 moved and the drag_on flag is set its current location given in the 3devent s x and y attributes is compared against the last location and camera is rotated accordingly When the mouse is clicked up we clear the drag_on flag The code handling the mouse_wheel_forward and _mouse_wheel_back events will call the 3dcamera s depth of field via the set_perspective method to implement zoom in and zoom out example 10 Getting mouse input preamble including the 3d m subsystems begin class my_window every my_window is a 3dwindow and has a drag_on a mouse_x last mouse position a mouse_y a phi camera angle about Y a omega a dof_angle overrides the action define drag_on mouse_x mouse_y dof_angle as integer variables define phi omega as double variables end define the_camera as a 3dcamera reference variable define _nearp 1 0 _farp 10 0 as constants near far clipping planes end method my_window action event check the event id against events to handle select case id event case 3devent _mouse_down let drag_on 1 let mouse_x x event let mouse_y y event case 3devent _mouse_move if drag_on lt gt 0 add x event mouse_x 0 1 to phi update camera angles add mouse_y y event 0 1 omega call set_forward the_camera 0 0 0 0 1 0 reset call rotate_y the_camera phi rotate camera about its Y axis call rotate
129. sed to control the camera so the key_code attribute should be compared with the _left_key right_key _up_key and _down_key constants We can also use the i and o keys to zoom in and out respectfully When the key_code attribute is equal to __literal_key the key_literal attribute will contain the alpha numeric code In our case the attribute can be compared with text constants o and i The action method implementation now looks like this method my_window action event check the event id against events to handle select case id event case 3devent _key_down select case key_code event case 3devent _left_key call move_camera 1 0 0 0 case 3devent _right_key call move_camera l a 0 0 case 3devent _up_key call move_camera 0 0 1 0 case 3devent _down_key call move_camera 0 0 1 0 case 3devent _literal_key select case key_literal event case i call zoom_camera 1 0 case o call zoom_camera 1 0 default endselect endselect default endselect return with _continue tell SIMSCRIPT to do default handling end 8 4 Selecting a node in the scene graph It can be helpful to an application user to have the ability to interact with a graphical simulation One of the nice things about adding mouse support to a simulation is the additional ability to click on visible objects in the 3dworld SIMSCRIPT 3 graphics allows actions to be taken whenever any 3dnode in a scene graph is clicked on
130. set_viewport as a method given 2 integer arguments x y in pixels 2 integer arguments width height pixels 1 integer argument 1 gt size viewport to window canvas Defines the viewport within the window that will display what is seen by the Camera Values are given in pixels with 0 0 located at the lower left corner of the window DEFAULT lt viewport_autosize 1 gt Two different types of projections are possible when using a 3dcamera orthographic and perspective When using orthographic projections the distance from the camera to the viewed object does not affect the size of its image seen on the canvas A simple view volume defines to portion of the 3d world that is seen by the camera This box is of course oriented and positioned with respect to the camera not the world The set_orthographic method specifies the view volume If the auto resize flag is specified the view volume will be adjusted automatically when the user resizes the window Values are specified relative to the camera s own orientation and location define set_orthographic as a method given 2 double arguments left right 2 double arguments bottom top 2 double arguments Yar near 1 integer argument 1 gt adjust size automatically after window resize sets up an orthogonal parallel projection It is assumed that the Teye is located at the location of the camera and looking down th
131. sresseessee 16 2A Shine the POSTION ofa NOE xs sosna E A a 17 2 5 Ro tating A NODE cgcsinieverciaveseesiaveesasaisdsvaashavadaase E R TEA E E TEE SATE 17 2A Scaling a noder cs ssi sesasecd guhexavecucetaeaeas eee as tay e neeo ES OER EES eeoa 18 2 5 C mplete SCENE SOP ap Ml example voceri ai a aes 18 3 1 Camera location and orientation sessseeseesessssereeseesresrersetsresressttstesressetseesressreseese 22 3 2 Setting up the viewing plane sesssessssseesssessessseresseeesseersseesseesseessseeesseesseesseessee 24 3 3 Adding a 3dcamera to the scene graph sseseeessseessseeesssetssressersseessseersseessresseessee 25 3 4 Viewports and multiple Cameras soc escscesycadavcsv eschctyas sovqoostaaueueace eoyacsteres teak eae 26 3 5 Tracking a moving object with the 3dcamera eesceescecesneeceenececeeneeceeeeeesseeeesaes 27 4 Lighting up a scene graph ccce origis eisein AA iE ERE E iaa 31 4 1 Determining the variety of lighting sesesesessssseesseeessesseessersserssseeesseesseesseessee 31 4 2 Ambient Diffuse and Specular light 22 tend wee tena ein aan 32 4 3 Setting up the lighting using the 3dlight 0sssessneeesssessesssesssseessessseeesseessersseessee 34 5 Loading graphics files via Models sscccisccctsrepates dots lusnazsngicgnasedocaaleageos tues scasdaedebendtasguadatees 37 5 1 Reading in the 3dmodel from a file ceeseeceeneeceeeeeceeneeceeneeceeceeceeeeeeesteeeesaes 37 5 2 Linking a 3dmodel
132. sseesesscsseseeeees 67 7 1 Setting the color and shininess of a surface nssessssessesssessseeesseessseeesseessersseessee 67 7 2 Texture mapping and raster images ssssssessseeesseeesstessesseesseeeseeessstessresseesseeessee 68 7 3 Front and back side VaSIDIILYssssccoceiest orceatansveassasvevesndssacaetat sagesat eaacontaneeeiatence agers 71 7 4 Using instances of Samm ater ial yac ce4 ices aczsicusteacadeies capdexededeyduceashaneduuecesaaecetsbededenguecanns 12 8 User TMP eec e or e aaa r E E E EA EE E a aS 75 8 1 Mouse keyboard and window frame interaction c cceseceesseceeeeeceesteeeeneeeeaees 75 8 2 MOUSE Cvens ie ote eee i a E E E E EEE EER A 76 Valte irises iii eranen kiii eri A a ESENE T a ETIE ESEESE TESE nan pei 76 Value ese ee a a seed alt E AE S E Ae see seared 76 Valter mrn a a ete a a A a E R eg as Ti Walli at Seatac Geet ye eae a eo ie eae aaa eh ete ei ee ale 77 IV ALG sc 29 scares tastes fal Tepes Gel hada geass dah e Nec Oacasbelah Goa tait ial ana Paaere Tel hes 11 B D Keyboard Inp t 52303 se2 lt ada sd shan anes sscees aus caeeussiedaanasdanan uauhedede A R AE R 79 8 4 Selecting a node in the scene graph ssssesesssesssssesssetsseessersserssseessstesseesseesseeesseee 80 9 Animation ANG SIMUL AU onein sii ie E aa AE E ES e S amas 84 9 1 Frame Based Animation seseseesseseseseeseesessesrrestesererssressresressesstestesseestesreeseeseeseeesee 84 oI Da TT E E AE E A E AEE E E EEE 84 9 3 A
133. t Set name Member Description camera_set 3dcamera cameras used to show the scene graph light_set 3dlight light sources in the scene material_set 3dmaterial materials used by 3dnodes in the scene graph model_set 3dmodel models used by nodes in the scene graph node_set 3dnode forms the scene graph 2 2 Setting the location of a node Properties of the 3dnode are its location and orientation The location_x location_y and location_y attributes represent the x y and z coordinates of the node s position with respect to its owner node in the scene graph Right handed use of these attributes is allowed but the set_location method should be used to set these attributes Suppose the simulation was to show a ferry shuttling passengers Some of the code that might be used to build the scene graph and position the objects is put all passengers on the ferry by filing Tinto the node set owned by the_ferry instance For I 1 to 100 File this passenger i in node_set the_ferry set z location of the ferry Passengers will move with the ferry let location_z the_ferry 1000 0 set a passengers position with respect to ferry call set_location passenger 2 2 5 0 0 34 9 15 2 3 Setting the orientation of a node The orientation of a node can be defined by 2 vectors forward and up See Figure 2 2 The forward vector indicated the direction of the local z axis relat
134. t 3dbox Found in 3dshapes m Cubes width height depth 3dcone Simple cone shape length radius attributes 3dcylinder Simple cylinder shape length radius attributes 3dellipse 2d circle arc pie or ellipse in 3d space radius_x radius_y start_angle stop_angle 3drectangle 2d rectangle in 3d space height width 3dsphere Simple sphere shape radius 6 1 Using the 3dgraphic class Occasionally there are cases where the exact shape is not known until runtime For example a simulation shown a 3d terrain landscape may not know the geographical area to display until runtime Even then the coordinates of the hills and valleys may reside in a data file which must be decoded and the vertex information extracted or computed We can handle this case using the 3dgraphic class Geometry and surface materials are specified by sub classing 3dgraphic and overriding the draw method The draw method is called automatically when the system needs to have the 3dgraphic object rendered Calling the 3dwindow display method will invoke 45 this method Draw may also be called as a result of event handling The draw method should be programmed to make calls to begin_drawing and end_drawing class methods to define each surface After the call to begin_drawing calls to class methods such as draw_normal draw_texture_coordinate and draw_vertex allow geometry to be specified for the surface A call to end_drawing will mark the end of the geometry desc
135. t defines attributes that need to be copied with the rest of the components In our tank example suppose the turret class defines attributes azimuth and attitude that are initializes in the model We want these values to be propagated when turret is copied via the load method 111 Begin class turret Every turret is a 3dnode and has A azimuth An attitude and Overrides the copy_attributes Define azimuth attitude as double variables End The copy_attributes method s implementation would look like this method turret copy_attributes node define p as a pointer variable define original_turret as a turret reference variable let p node necessary due to original prototyping let original_turret p let azimuth azimuth original_turret let attitude attitude original_turret call 3dshape copy_attributes node end There are a couple more options regarding the 3dmodel that can be set before the model is read from the file They are _smoothing and _cache_model The options are set via a left handed use of the enabled method For example define the_model as a 3dmodel reference variable let enabled the_model 3dmodel smoothing 1 turn on smoothing let enabled the_model 3dmodel smoothing 0 turn off smoothing The _smoothing option will cause normal vectors to be recomputed at the time the model is read from the file This will give a smooth appearance of the mod
136. tank2 find tank2 turret1 5 6 Deriving from sub components Suppose the application wanted to represent the turret sub component of a tank using an object derived from 3dnode instead of the 3dnode base class In this case the 3dmodel would be sub classed and its create_component method overridden define create_component as a virtual 3dnode reference method given 1 text argument name of the component 1 text argument name of required class This method is called by the system during the execution of the read method to create a new sub node component The name given to the component in the model file is provided in argument 1 By default this method will create a instance of the class named by argument 2 but can be overridden to create a sub class of arg 2 39 Create_component is called automatically for each separate component that is created at the time a 3dmodel is read Overriding this method allows you to create and return the correct sub class that should represent the component In the above example create_component would be implemented to create and return a turret object if the first argument specified the name assigned to the turret component in the graphics editor See below method tank_model create_component component_name class_name define my_turret as a turret reference variable if component_name turretl and class_name 3dnode create a turret called my_turret return with my
137. te Continuous Simulation using SIMSCRIPT II 5 A description of SIMSCRIPT II 5 unique capability for modeling combined discrete continuous simulations e SIMSCRIPT II 5 Programming Language A description of the programming techniques used in SIMSCRIPT II 5 e SIMSCRIPT II 5 Reference Handbook A complete description of the SIMSCRIPT II 5 programming language without graphics constructs e Introduction to Simulation using SIMSCRIPT II 5 A book An introduction to simulation with several simple SIMSCRIPT II 5 examples e Building Simulation Models with SIMSCRIPT II 5 A book An introduction to building simulation models with SIMSCRIPT II 5 with examples The SIMSCRIPT language and its implementations are proprietary software products of the CACI Products Company Distribution maintenance and documentation of the SIMSCRIPT language and compilers are available exclusively from CACI Free Trial Offer SIMSCRIPT III is available on a free trial basis We provide everything needed for a complete evaluation on your computer There is no risk to you Training Courses Training courses in SIMSCRIPT III are scheduled on a recurring basis in the following locations San Diego California Washington D C On site instruction is available Contact CACI for details For information on free trials or training please contact the following CACTI Products Company 1455 Frazee Road suite 700 San Diego California 92108
138. te is also useful for setting the background color It can be assigned a value obtained from the gui m color class and by default is set to gui m color _black The window is made visible and updated by calling its display method The following code displays a 3dwindow in the upper right corner of the computer screen Define window as a 3dwindow reference variable Create window Let title window Let color window Hello window gui m color _blue Let position_xlo window 32767 0 2 0 Let position_ylo window 32767 0 2 0 Let position_xhi window 32767 0 Let position_yhi window 32767 0 Call display window Instances of the 3dworld object that are to be shown in the window s canvas must be filed into the world_set owned by the 3dwindow See figure 14 If more than one 3dworld is being used all nodes contained in the 3dworld filed last in the world_set will be displayed on top of nodes attached to other worlds regardless of the distance from the camera The depth buffer is cleared before each world is displayed 3dwindow world set 3dworld ode_set 3dworld 3dnode 3dnode 3dnode 3dnode 3dnode 3dnode 122 Figure 19 The 3dwindow s relationship to the scene graph Sub classes of 3dwindow can override the action method This method is called automatically in response to a user driven event The action method takes a 3devent reference argument and the following event ids are currently supported
139. te process method is called all 3dworld instances attached to the 3dwindow world_set will be automatically and frequently updated as simulation time is scaled to real time see timescale v 3dnode instances can be filed into the 3d m motion_set to enable the motion method to be called as time is advanced The change in simulation time is passed as the argument to motion Sub classes of 3dnode can override the motion method making calls to move set_forward etc based on the elapsed time define motion as a virtual method given 1 double argument dt Time elapesed since last call 116 If simple linear movement is required the set_velocity method can be called A velocity vector is given whose components define the speed along the x y and z axes respectfully Velocity is set with respect to the owner node s coordinate system If a velocity is specified the set_location method is called automatically by the 3dnode motion method to update the location If motion is overridden 3dnode motion must be called if the velocity attributes are set A 3dnode instance must be filed in the motion_set for velocity to take effect define velocity_x velocity_y velocity_z as double methods define set_velocity as a method given 3 double arguments yvelocity_x velocity_y velocity_z The move_to process method is convenient way to tell a 3dnode instance to travel to a location in 3d space with a certain speed The first three arguments specify th
140. te the world create world file this world in world_set window create a light source and point it in the same direction as the camera create light call set_forward light 0 0 0 0 1 0 file this light in light_set world create a background node to hold the objects 28 create background file this background in node_set world add to root of scene graph create the one model for the tank create tank_model call read tank_model tank 3ds file tank_model in model_set world create the tank node create the_tank let model the_tank tank_model file the_tank in node_set world Tadd to root of scene graph file the_tank in motion_set create the tank camera It will be attached to the tank s 3dnode so that it will show the view out of the tank create tank_camera call set_perspective tank_camera 60 0 1 0 0 1 115 0 1 call set_forward tank_camera 0 0 0 0 1 0 call set_location tank_camera 0 0 4 0 0 0 call set_viewport tank_camera 0 0 canvas_width window 2 canvas_height window 1 file tank_camera in camera_set world file tank_camera in node_set the_tank create the lot camera place it along positive z axis but point it down the negative z direction create lot_camera call set_perspective lot_camera 60 0 1 0 0 1 115 0 1 call set_forward lot_camera 0 0 0 0 1 0 call set_location lot_camera 0 0 4 0 60 0 call set_viewport lot_cam
141. tems begin class torus every torus is a 3dgraphic and has a material numMajor numMinor minorRadius majorRadius and overrides the draw oo o define material as a 3dmaterial reference variable define numMajor numMinor as integer variables define minorRadius majorRadius as double variables end end this method is called automatically We will provide the code needed to draw a torus method torus draw define nx ny nz as double variables define a0 al x0 y0 x1 yl as double variables define b c r z majorStep minorStep as double variables define i j as integer variables let majorStep 2 0 pi c numMajor let minorStep 2 0 pi c numMinor call set_material material for i 0 to numMajor 1l do a0 i majorStep al a0 majorStep x0 cos f a0 yO sin f a0 xl cos f al yl sin f al call begin_drawing _quad_strip for j 0 to numMinor j minorStep cos f b minorRadius c majorRadius minorRadius sin f b NB Bka O Il for texture coordinates map entire surface of torus to 0 1 call 3d m vector_normalize x0 c y0 c z minorRadius yielding nx ny nz call draw_texture_coordinate j numMinor i numMajor call draw_normal nx ny nz call draw_vertex x0 r y0 r z call 3d m vector_normalize xl c yl c z minorRadius yielding nx ny nz 55 call draw_texture_coordinate j numMinor i 1 numMajor call draw_normal nx ny nz call draw_vertex xl r
142. tomatically based on the object s size attributes Since shapes are derived from from the 3dnode class they can be positioned oriented moved over time etc Currently available shapes include the 3dbox 3dcone 3dcylinder 3drectangle and 3dsphere The material attribute can be used to specify a 3dmaterial instance to be used on the surface of the shape Currently texture mapping is only supported for the 3dsphere 3dbox and 3drectangle shapes If the texture_name attribute of 3dmaterial is assigned the texture coordinates will be computed automatically such that the entire texture is mapped to the surface of the shape If the inside_lighting attribute is assigned to 1 all normal vectors will be reversed This can be useful if the 3dcamera is placed inside the object By default inside_lighting is Zero 3dsphere lineage 3dsphere gt 3dshape gt 3dgraphic gt 3dnode The 3dsphere can be created to show a sphere object in a 3d graphics scene Its radius attribute controls the size of the sphere The color of the sphere can be specified by assigning a 3dmaterial instance to its material attribute If this material s texture_name attribute is assigned the texture image will be wrapped around the shape of the sphere If the 3dcamera will be placed inside the sphere the inside_lighting attribute should be assigned to 1 3dtext lineage 3dtext gt 3dgraphic gt 3dnode The 3dtext is derived from 3dgraphic a
143. track the node automatically even if both objects are moving The camera will remain oriented so that the global y axis appears to point up Tracking can be stopped by assigning tracked_node to zero define tracked_node as a 3dnode reference variable monitored on the left Can be assigned to a 3dnode in the same 3dworld Will cause the camera to automatically point to the given node Must be assigned to zero before the tracked_node can be destroyed 3dcone lineage 3dcone gt 3dshape gt 3dgraphic gt 3dnode The 3dcone can be created and filed into a node_set to add a cone shaped object to the scene graph The distance from its tip to base can be set by assigning the length attribute Its radius attribute controls the radius of its base circle The default value for both dimensions is 1 0 3dcylinder lineage 3dcylinder gt 3dshape gt 3dgraphic gt 3dnode The 3dcylinder can be created and filed into a node_set to add a cylinder shaped object to the scene graph Its size can be adjusted by setting its length and radius attributes The default value for both dimensions is 1 0 3dellipse lineage 3dellipse gt 3dshape gt 3dgraphic gt 3dnode The 3dellipse can be created and filed into a node_set to add a circle or ellipse object to the scene graph This object can actually be used to draw a variety of shapes depending on the hollow and shape_mode attributes hollow
144. ts as the root of all scene graphs to be displayed on its canvas Basically the rule is that every object that is to be made visible with the exception of the 3dwindow must be filed into an appropriate set or it will not be shown The figure below shows a diagram of a scene graph Sdwindow 3d world control panel node set Sdnode thousing cannon Figure 2 1 A typical scene graph for a tank and a battlefield The code for creating this scene graph would look something like this 14 Define window as a 3dwindow reference variable Define battlefield control_panel as a 3dworld reference variable Define tank body turret housing cannon terrain ground obstacles As 3dnode reference variables create window battlefield control_panel create tank body turret housing cannon terrain ground obstacles file this housing in node_set turret file this cannon in node_set turret file this turret in node_set tank file this body in node_set tank file this tank in node_set battlefield file this ground in node_set terrain file this obstacles in node_set terrain file this terrain in node_set battlefield file this battlefield in world_set window file this control_panel in world_set window The 3dworld also acts as a container for other objects that are employed by nodes in the attached scene graph The table below lists the various sets owned by a 3dworld objec
145. ttribute to an rgb value returned from the gui m color rgb class method If less ambient light is required darker colors should be used For example setting ambient_color to color rgb 0 25 0 25 0 25 will provide a 1 4 intensity of ambient light Diffuse Diffuse light is reflected from a surface in all directions The amount of reflected light is determined by the diffuse color of surface material see 3dmaterial Rough surfaces should have a relatively bright diffuse_color attribute Both diffuse and specular light allows objects to be shaded based on surface normal vectors Surface elements with normals pointing at the light source will be illuminated while surfaces with normals orthogonal to the light source s direction will not The diffuse_color attribute determines the color and intensity of diffuse light Specular Specular light is reflected from a surface in mostly one direction Shiny surfaces reflect more of the specular light than rough surfaces The amount of reflected light is determined by the specular color of surface material see 3dmaterial Surface elements with normals pointing at the light source will be illuminated while surfaces with normals orthogonal to the light source s direction will not The specular_color attribute determines the color and intensity of this light All color related attributes defined in the 3d m subsystem are specified in terms of an rgb triple This is an integer returned fro
146. turret called my_turret return with my_turret otherwise return with 3dmodel create_component component_name class_name end In some cases the application may require individual images of a 3dmodel to appear differently For example if many tanks were to be displayed each turret will have a different orientation In this case the 3dnode load method would be called This method will make copies of each sub component and place the nodes into the appropriate node_set In the following code two tanks are loaded from a common model read from the file tank 3ds The turret on the first tank is rotated 90 degrees while the second turret is rotated 45 degrees Define tankl tank2 as tank reference variables Define the_model as a tank_model reference variable Create tankl tank2 the _model File the_model in model_set the_world File tankl in node_set the_world File tank2 in node_set the_world Ca read the_model tank 3ds create_component called Call load tank1 the_model copy_attributes called Call load tank2 the_model Call rotate_y find tankl1l Turret_for_tank pi c 2 0 Call rotate_y find tank2 Turret_for_tank pi c 4 0 In the above example the load method call makes copies of all components in the model Individual attributes are copied by an internal call to the copy_attributesmethod The sub class can override this method if i
147. uch in the same way that a real camera would be positioned A 3dcamera can optionally be filed into a node_set allowing it to move and rotate automatically with the owner node For example a 3dcamera could be filed into the node_set owned by a jet plane and if positioned at the cockpit would provide the same shifting view of scenery that a pilot would see as the plane flies The portion of the 3dworld seen by the camera is projected onto a rectangular area of the canvas called a viewport Normally the viewport dimensions will match the canvas dimensions In fact if the viewport_autosize attribute of 3dcamera is non zero default the view will automatically size to match the canvas whenever the user resizes the window However if more than one camera is present the multiple views should be mapped to different regions of the canvas The set_viewport method specifies the viewport rectangle in pixels with the 0 0 coordinate located at the lower left corner of the canvas The call to set_viewport will usually have to be made in response to the user resizing the window At this time the new pixel dimensions of the canvas are known allowing the viewport to be sized appropriately This can be accomplished by sub classing the 3dwindow object and overriding the action method If the event id is 93 66 99 66 99 _resize then the x and y attributes of the event will have the new size of the window oe define
148. uppose we wanted to show a 3d object move in a straight line from 2 0 0 0 0 0 to 2 0 0 0 0 0 A process method is written that in a loop calls the set_location method to update the position of the object then waits a small amount of time called _delta_x process method car move_it define x as a double variable define _delta_x 1 0 _speed 10 0 as constants for x 20 0 to 20 0 by _delta_x do call set_location x 0 0 0 0 wait _delta_x _speed units loop end In the preceding example the smoothness of the motion depends on the _delta_x constant If this constant is made smaller the motion will smooth out However a problem with reducing this value is that it will increase the number of wait statement executions For example changing _delta_x from 1 0 to 0 01 will increase the number of iterations of the loop from 40 to 4000 If hundreds of objects were moving around that could lead to millions of process switches just to support movement Fortunately SIMSCRIPT 3d graphics provides a better way to support animated motion The 3d m subsystem owns a set called motion_set 3dnode instances can be filed into this set to have their movement updated automatically The runtime library will call the motion method for every 3dnode filed into the motion_set before refreshing the window canvases The default behavior of motion is to update the location of the 3dnode based on its velocity which can be assigned by calling the set_velo
149. utomatic motion and the motion_set sssessessseeesesessseesseessessseresseeesseesseesseesseee 85 9 4 Moving Car Examples cnsrenhnoncinssi nisn a a a i 86 9 5 Achieving customized motion ss ssssssesssesesssetsseesserssetsseeesstesstessersseeesseeesstesseesse 87 103d Class reference nienia e nh ech E E E E E ot soeneme cs 93 3dbox lineage 3dbox gt 3dshape gt 3dgraphic gt 3dnode ssssseesseeeesseesseesseessee 93 3dcamera lineage 3dcamera gt 3dnode ssesssessensseeeseeeesseesseesseesseresseeesseesseesseesseee 93 3dcone lineage 3dcone gt 3dshape gt 3dgraphic gt 3dnode ssssesessesesseessesssesesee 95 3dcylinder lineage 3dcylinder gt 3dshape gt 3dgraphic gt 3dnode eee 95 3dellipse lineage 3dellipse gt 3dshape gt 3dgraphic gt 3dnode eeeeeeeseeeeeees 95 3devent lineage 3devent gt gui m guievent 00 0 eee eeeeeceececeeeeeceeeeeceeeeceeeeceeeeenaes 96 3dfaces lineage 3dfaces gt 3dgraphic gt 3dnOde 0 0 ee eeeceeseeceeeeeceeeeeceeeeecteeeeeesaes 97 Sdgraphic lineage 3dgraphic gt SANOE csesiiaiiiss incyisussasavasyenssagelcaenncsdvcheessvaxacesssnevaer 102 3dlight lineage 3dlight gt 3dnode x ccisst sie aja casccustonsedtsasetessat encesdea ceqeenas acca aonreeestes 105 3dlines lineage 3dlines gt 3dgraphic gt 3dnode ee eeeeeeeeeceeeeeeeceteeeeeeeeeesteeeenee 106 SOMALIA essesi asirini annia sia E pE EEEE dat ens S
150. ys or any other such visual aids that are separate from the 3d scene but appear in the same window Graphics in multiple worlds will not interleave but overlap regardless of the distance from viewer The 3dworld class is used to implement a world Nodes contained in the scene can have animated motion that is linked to elapsing simulation time 1 1 A Typical 3d Graphics Program A typical 3d graphical simulation will display many graphical objects which may or may not be moving with respect to simulation time Light sources and cameras must be created To create such a program the following steps should be performed 1 Write customized drawing code if necessary a Define sub classes of 3dgraphic in the preamble and override the draw method b In the implementation of draw make calls to begin_drawing and end_drawing c Between begin_drawing and end_drawing make calls to 3dgraphic class methods to define the vertices normal vectors texture coordinates and materials of the shape 2 Write event handling code if necessary a If keyboard input mouse input or window resize handling is needed define in the preamble a subclass of 3dwindow and override its action method b Implement the action method by writing code to inspect the attributes of the 3devent instance passed as its argument and perform the necessary processing 3 Create windows and worlds a For each window that is needed cre

SIMSCRIPT III 3d Graphics Manual

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