G3dRender.mesa
Copyright Ó 1985, 1989 by Xerox Corporation. All rights reserved.
Bloomenthal, February 14, 1989 1:48:23 pm PST
Crow, April 21, 1989 12:56:08 pm PDT
DIRECTORY Atom, G3dBasic, G3dMatrix, G3dShape, Imager, ImagerPixel, ImagerSample, ImagerColor, IO, Rope, Terminal, ViewerClasses;
G3dRender: CEDAR DEFINITIONS
~ BEGIN
Errors
Error:     SIGNAL [code: ATOM, reason: ROPE]; -- we're able to resume this error
Types
Miscellaneous Types
ROPE:     TYPE ~ Rope.ROPE;
PropList:    TYPE ~ Atom.PropList;
Virtual:    TYPE ~ Terminal.Virtual;
Viewer:    TYPE ~ ViewerClasses.Viewer;
RefSeq:    TYPE ~ REF RefSeqRep;
RefSeqRep:   TYPE ~ RECORD [
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF REF
];
Imported Sequences
RealSequence:  TYPE ~ G3dBasic.RealSequence;
IntegerSequence:  TYPE ~ G3dBasic.IntegerSequence;
IntSequence:   TYPE ~ G3dBasic.IntSequence;
NatSequence:   TYPE ~ G3dBasic.NatSequence;
NatSequenceRep:  TYPE ~ G3dBasic.NatSequenceRep;
PairSequence:  TYPE ~ G3dBasic.PairSequence;
IntegerPairSequence: TYPE ~ G3dBasic.IntegerPairSequence;
TripleSequence:  TYPE ~ G3dBasic.TripleSequence;
QuadSequence:  TYPE ~ G3dBasic.QuadSequence;
Pixel Definitions
RGB:      TYPE ~ ImagerColor.RGB;
RGBSequence:  TYPE ~ REF RGBSequenceRep;
RGBSequenceRep: TYPE ~ RECORD [
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF RGB
];
NatRGB:    TYPE ~ RECORD [r, g, b: NAT];
NatRGBSequence:  TYPE ~ REF NatRGBSequenceRep;
NatRGBSequenceRep: TYPE ~ RECORD [
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF NatRGB
];
Spot:     TYPE ~ RECORD [
coverage:      REAL ← 1.0,    -- % of pixel area covered by surface
mask:       BYTE ← 255,   -- code for covered area, default: all covered
partShiny:     REAL ← 1.0,   -- amount shiny surface shows (1.0 = all)
val:       RealSequence ← NIL, -- interpolated values for shading
yIncr:       RealSequence ← NIL, -- vertical increments for interpolation
xIncr:       RealSequence ← NIL, -- horizontal increments for interpolation
xySwapped:     BOOL,     -- if TRUE, xincr and yincr are swapped
props:       PropList ← NIL  -- catchall
];
SpotProc:    TYPE ~ PROC [
context:      Context,
shading:      REF ShadingClass,
spot:       REF Spot,
data:       REF ANY ← NIL];
PixelPart:    TYPE ~ {r, g, b, a, z};      -- addressing within Pixels
Pixel:      TYPE ~ ARRAY PixelPart OF CARDINAL; -- r, g, b, alpha, z (depth)
Geometric Definitions
Pair:     TYPE ~ G3dBasic.Pair;
IntegerPair:   TYPE ~ G3dBasic.IntegerPair;   -- RECORD [x, y: INTEGER];
Triple:    TYPE ~ G3dBasic.Triple;
Quad:     TYPE ~ G3dBasic.Quad;     -- RECORD [x, y, z, w: REAL];
Matrix:    TYPE ~ G3dMatrix.Matrix;    -- REF 4 by 4 ARRAY OF REAL
MatrixRep:   TYPE ~ G3dMatrix.MatrixRep;
Image Definitions
SampleMap:   TYPE ~ ImagerSample.SampleMap;
PixelMap:    TYPE ~ ImagerPixel.PixelMap;
Box:     TYPE ~ G3dShape.Box2d;   -- [min, max: Pair]
Rectangle:    TYPE ~ Imager.Rectangle;  -- RECORD [x, y, w, h: REAL]
ScaleAndAddXfm:  TYPE ~ RECORD [scaleX, scaleY, scaleZ, addX, addY, addZ: REAL];
ClipState:    TYPE ~ G3dShape.ClipState;    -- {in, out, clipped, unknown}
OutCode:    TYPE ~ RECORD [left, right, bottom, top, near, far: BOOL];
SixSides:    TYPE ~ {Left, Right, Bottom, Top, Near, Far};
Constants
NoneOut:    OutCode ~ [FALSE, FALSE, FALSE, FALSE, FALSE, FALSE];
AllOut:    OutCode ~ [TRUE, TRUE, TRUE, TRUE, TRUE, TRUE];
IdentityXfm:   ScaleAndAddXfm ~ [1.0, 1.0, 1.0, 0.0, 0.0, 0.0];
Texture Definitions
TextureFunction: TYPE ~ RECORD [name: ATOM, proc: SpotProc, props: PropList];
TextureMap:   TYPE ~ RECORD [type: ATOM, pixels: REF ANY, props: Atom.PropList];
SummedTexture:  TYPE ~ RECORD [SEQUENCE length: NAT OF REF SumSequence];
SumSequence:  TYPE ~ RECORD [SEQUENCE length: NAT OF IntSequence];
Control Point Definitions
CtlPoint:    TYPE ~ RECORD[
x,y,z:       REAL ← 0.0,      -- object coordinates
ex, ey, ez:     REAL ← 0.0,      -- eyespace coordinates
sx, sy, sz:     REAL ← 0.0,      -- screen coordinates
clip:       OutCode ← NoneOut  -- clip code
];
CtlPointSequence: TYPE ~ REF CtlPointSequenceRep;
CtlPointSequenceRep: TYPE ~ RECORD[
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF REF CtlPoint
];
Shading:    TYPE ~ RECORD [
xn, yn, zn:     REAL ← 0.0, -- normal vector to surface
exn, eyn, ezn:    REAL ← 0.0,  -- normal in eyespace
r, g, b:      REAL ← 1.0, -- vertex color (default white) scaled by shape color
t:        REAL ← 1.0, -- original transmittance
txtrX, txtrY:     REAL ← 0.0, -- texture mapping coordinates
er, eg, eb, et:    REAL ← 0.0  -- computed color, transmittance (for lights, etc)
];
ShadingSequence: TYPE ~ REF ShadingSequenceRep;
ShadingSequenceRep: TYPE ~ RECORD[
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF REF Shading
];
CtlPtInfo:    TYPE ~ RECORD [
coord:       CtlPoint ← [],
shade:       Shading ← [],
vtxPtr:      NAT ← 0,
data:       REF ← NIL
];
CtlPtInfoSequence: TYPE ~ REF CtlPtInfoSequenceRep;
CtlPtInfoSequenceRep: TYPE ~ RECORD [
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF REF CtlPtInfo
];
CtlPtInfoProc:  TYPE ~ PROC [context: Context, vtx: CtlPtInfo, data: REF ANY ← NIL]
         RETURNS [CtlPtInfo];
CtlPtToRealSeqProc: TYPE ~ PROC [dest: RealSequence, source: CtlPtInfo, data: REF ← NIL]
        RETURNS [RealSequence];
Patch Definitions
FacingDir:   TYPE ~ {front, back, unknown};
Patch:     TYPE ~ RECORD [
type:       ATOM ← NIL,
oneSided:      BOOL ← TRUE,
nVtces:      NAT ← 0,
clipState:      ClipState ← unknown,
dir:       FacingDir ← unknown,
renderData:     REF RenderData,
props:       PropList ← NIL,
ctlPt:       SEQUENCE maxLength: NAT OF CtlPtInfo
];
Implemented patch types: $ConvexPolygon, $Bezier
Standard uses for props: $Shape (parent shape)
PatchSequence:  TYPE ~ REF PatchSequenceRep;
PatchSequenceRep: TYPE ~ RECORD [
length:      CARDINAL ← 0,
element:      SEQUENCE maxLength: CARDINAL OF REF Patch
];
PatchProc:   TYPE ~ PROC [context: Context, patch: REF Patch, data: REF ANY ← NIL]
          RETURNS [REF Patch];
Shape Definitions
Shape:     TYPE ~ G3dShape.Shape;
ShapeSequence:  TYPE ~ G3dShape.ShapeSequence;
RenderData:   TYPE ~ RECORD [      -- becomes shape.renderData 
class:       REF ShapeClass ← NIL,  -- surface type, display procs
shadingClass:    REF ShadingClass ← NIL, -- shading parameters and procs
props:       PropList ← NIL,    -- catchall ($LinesList, $Hidden)
fixedProps:     PropList ← NIL,    -- fixed attributes
shadingProps:    PropList ← NIL,    -- shading status and parameters
patch:       PatchSequence ← NIL,  -- built from vertex and surface data
patchesValid:    BOOL ← FALSE     -- FALSE if patches need update
];
Uses for RenderData.props:
$ClippedPatches, $ClippedVertices, $Hidden, $LinesList,
Uses for RenderData.fixedProps:
$Closed, $PatchColors, $PatchColorsInFile, $PatchInfo, $PatchNormalsInFile, $PatchTransmittancesInFile, $VertexColorsInFile, $VertexNormalsInFile, $VertexTextureInFile, $VertexTransmittanceInFile
Uses for RenderData.shadingProps:
$AuxiliaryVtxData, $PolygonInfoComputed, $Scale, $ShapeLerp, $TextureScale, $TxtrCoordParams, $TxtrCoordRange, $TxtrCoordType, $TxtrTranslation, $VtxInfoComputed
ShapeClass:   TYPE ~ RECORD [
type:       ATOM ← NIL,   -- eg, $ConvexPolygon, $Bezier, $Light, etc
validate:      ShapeProc ← NIL, -- update vtces and shading after changes
display:      ShapeProc ← NIL, -- display whole shape (speed optimized?)
displayPatch:     PatchProc ← NIL, -- display patch
doBeforeFrame:    LIST OF ShapeProc ← NIL -- do before disp. (for animation, etc)
];
ShadingClass:  TYPE ~ RECORD [
type:       ATOM ← NIL,   -- eg. $Default, $MappedAndSolidTexture
renderMethod:    REF ← NIL,   -- RenderStyle, or ShapeProc
color:       RGB ← [0.7, 0.7, 0.7], -- whole object color, mixable w/ vtx color
shininess:     REAL ← 0.0,   -- hilight power, usu. 30.0-300.0, 0 = none
transmittance:    REAL ← 0.0,    -- surface transmittance of object
texture:      LIST OF REF ANY ← NIL,-- textureMap, solid texture, etc.
textureScale:     Pair ← [1.0, 1.0],   -- scale factors for texture coordinates
bumpScale:     REAL ← 1.0,    -- scale factor for bump height
cnvrtVtx:      CtlPtToRealSeqProc ← NIL,-- converts vertex to sequence of reals
getColor:      SpotProc ← NIL,   -- calculates shade at pixel
shadeVtx:      CtlPtInfoProc ← NIL  -- calculates shade from vertex info
];
    
ShapeProc:   TYPE ~ PROC [context: Context, shape: Shape, data: REF ANY ← NIL]
        RETURNS [Shape];
Context Definition
Context:  TYPE ~ REF ContextRep;
ContextRep: TYPE ~ RECORD [
Miscellany
class:    REF ContextClass ← NIL,
stopMe:    REF BOOL ← NIL,  -- stop flag for bailing out (ref for inheritance)
imageReady:  BOOL ← FALSE,   -- flag for useable image in display
changed:   BOOL ← TRUE,    -- call SurfaceRender.ValidateContext if true
Scene description
frameNumber:  NAT ← 0,     -- current frame for animation routines
shapes:    ShapeSequence ← NIL, -- current collection of shapes and lights
visibleShapes:  ShapeSequence ← NIL, -- computed by SurfaceRender.ValidateContext
lightSources:  ShapeSequence ← NIL, -- computed by SurfaceRender.ValidateContext
environment:  PropList ← NIL,   -- for reflection map, ambient light proc, etc.
View description
eyePoint:   Triple ← [1.0, -5.0, 2.0], -- defines point from which view is seen
lookAt:    Triple ← [0.0, 0.0, 0.0], -- defines center of image and focus
rollAngle:   REAL ← 0.0,    -- rotational angle about direction of view
upDirection:   Triple ← [0.0, 0.0, 1.0], -- defines "heads-up" direction (redundant)
fieldOfView:  REAL ← 40.0,    -- horizontal angle included in field of view
window:    REF Rectangle ← NIL, -- window clips field of view in eyespace
hitherLimit:   REAL ← 1.0,    -- anything closer to eyepoint is clipped
yonLimit:   REAL ← 1000.0,   -- anything further from eyepoint is clipped
clippingPlanes:  ARRAY SixSides OF Quad, -- computed clip planes
eyeSpaceXfm:  Matrix ← NIL,   -- world space to eyespace
eyeToNdc:   ScaleAndAddXfm ← IdentityXfm, -- eyespace to normalized disp. coords
ndcToPixels:   ScaleAndAddXfm ← IdentityXfm, -- to screen coords
Display description
viewer:    Viewer,     -- viewer record if in Viewer ELSE NIL
terminal:    Virtual ← NIL,   -- virtual terminal for this context, if displayed
displayInValid:  BOOL ← TRUE,    -- true whenever display parameter updated
pixels:    PixelMap ← NIL,   -- where the bits are
pixelAspectRatio: REAL ← 1.0,    -- physical width/height of displayed pixel
viewPort:   REF Rectangle ← NIL, -- viewport in floating pt. display coordinates
preferredViewPort: Rectangle ← [0., 0., 65536., 65536.], -- maximum viewport size
screenExtent:  Box  ← [[0, 0], [0, 0]], -- bounds area used (while building image)
preferredRenderMode: ATOM ← NIL,   -- $Pixels, $Imager (fancy vs. device indep.)
displayProps:  PropList ← NIL,   -- $Depth, $Alpha (Pixel posn),
             -- $FullDisplayMemory, $ViewerAdjusted
Rendering Style
autoRedraw:   BOOL ← FALSE,   -- quick image hint, redraw if viewer changes
delayClear:   BOOL ← FALSE,   -- delay clearing buffer when rendering
doVisibly:   BOOL ← TRUE,   -- build image on display
antiAliasing:  BOOL ← FALSE,   -- flag for antialiasing and alpha buffer
depthBuffering:  BOOL ← FALSE,   -- buffer for cheap hidden-surface removal
depthResolution: NAT ← 8192,     -- number of buckets for depth sorting
sortSequence:  REF ← NIL,    -- shapes or surfaces sorted for display
props:    PropList ← NIL   -- catchall, global uses:
        $WDir    - working directory
        $Log     - log file for messages
        $BackGround  - background color or context (images)
        $DitherContext  - for dithering RGB to pseudocolor
        $OutputFile  - output file for interpress or animation
        $ImagerCtx   - context for Imager calls, if no viewer
        $SortToPriority  - forces priority sort, poly intersections
];
ContextClass: TYPE ~ RECORD [
displayType:   ATOM ← NIL,  -- includes:
            $PseudoColor,
            $Gray,
            $FullColor,
            $ImagerGray
            $ImagerDithered,
            $ImagerFullClr,
            $Bitmap,
            $Interpress
setUpDisplayType: ContextProc,   -- ensures there are bits to write, sets up colors
validateDisplay:  ContextProc,  -- makes sure viewPort changes, etc. take effect
render:    ContextProc,  -- call this to display the scene
loadBackground:  ContextProc,  -- clear to background
 2d drawing primitives use normalized display coordinates (-1.0 < x < 1.0, -.75 < y < .75)
draw2DLine:   PROC [context: Context, p1, p2: Pair, color: Pixel], -- display a line
draw2DPolygon:  PROC [context: Context, poly: PairSequence, color: Pixel],
draw2DRope:   PROC [context: Context, rope: ROPE, position: Pair,
         color: Pixel ←[255,255,128,0,0], size: REAL �, font: ROPE ←NIL],
displayPolygon:   PatchProc,         -- 3 dimensional shading 
drawInViewer:  PROC [context: Context, procRec: REF ImagerProcRec],
updateViewer:  ContextProc
];
ContextProc:  TYPE ~ PROC [context: Context, data: REF ANY ← NIL];
ImagerProc:  TYPE ~ PROC [context: Context, imagerCtx: Imager.Context, data: REF ← NIL];
ImagerProcRec: TYPE ~ RECORD [proc: ImagerProc, data: REF ANY ← NIL];
RopeProc:   TYPE ~ PROC [
       context: Context,
       rope: ROPE,
       position: Pair,
       color: Pixel ← [255,255,255,0,0],
       size: REAL ← 20,
       font: ROPE ← NIL];
Classes Registration
RegisterDisplayClass: PROC [class: ContextClass, type: ATOM];
Add class to list of registered ContextClasses, containing display-specific procs, etc.
GetDisplayClass: PROC [type: ATOM] RETURNS [class: ContextClass];
Retrieve registered class for use or modification.
LoadDisplayClass: PROC [context: Context, type: ATOM];
Set proper color map and rendering procs.
RegisterShapeClass: PROC [class: ShapeClass, type: ATOM];
Add class to list of registered ShapeClasses, containing surface-specific procs, etc.
GetShapeClass: PROC [type: ATOM] RETURNS [class: ShapeClass];
Retrieve registered class for use or modification.
LoadShapeClass: PROC [shape: Shape, type: ATOM ← $ConvexPolygon];
Load ShapeClass (patch expansion and rendering procs) and ShadingClass for surface type.
RegisterShadingClass: PROC [class: ShadingClass, type: ATOM];
Add class to list of registered ShadingClasses, for fancy texturing procs, etc.
GetShadingClass: PROC [type: ATOM] RETURNS [class: ShadingClass];
Retrieve registered class for use or modification.
LoadShadingClass: PUBLIC PROC [shape: Shape, type: ATOM ← $Default];
Put ShadingClass in shape record.
Context
Create: PROC RETURNS [Context];
Allocate a context
.
InitializeRawColorDisplayContext: PROC [
antiAliasing: BOOL ← TRUE,
background: RGB ← [0.2, 0.2, 0.7],
displayMode: DisplayMode ← gray]
RETURNS [context: Context];
Return an initialized Context (one light source, nominal viewpoint).
This call will utilize the entire color display without the Viewers mechanism.
CloseDisplay: PROC [context: Context];
Shut down display gracefully, restore standard color map.
CloseColorViewers: PROC;
Close any open viewers on the color display.
KillUntitledColorViewers: PROC;
Kill any untitled color viewers (presumably the unwanted G3dRender viewer).
GetTmpContext: PUBLIC PROC [srcCtx: Context] RETURNS[dstCtx: Context];
copies context so temporary modifications can be made (don't change shapes however
CopyContextData: PUBLIC PROC [dstCtx, srcCtx: Context];
copies REFed data to dstCtx to insulate srcCtx from changes (except for shapes)
CopyContextShapes: PUBLIC PROC [dstCtx, srcCtx: Context];
copies shape data to dstCtx to insulate srcCtx shapes from changes
View
SetViewFromParameters: PROC [
context: Context,
fieldOfView: REAL ← 40.0,
scale: REAL ← 1.0,
moves, rotates: Triple ← []];
Set the context view according to parameters. If fieldOfView = 0, it will be set to 40.
SetView: PROC [
context: Context,
eyePoint: Triple,
lookAt: Triple,
fieldOfView: REAL ← 40.0,
rollAngle: REAL ← 0.0,
upDirection: Triple ← [0., 0., 1.],
hitherLimit: REAL ← .01,
yonLimit: REAL ← 1000.0];
Set the context view according to camera geometry. If fieldOfView = 0, it will be set to 40.
SetViewPort: PROC [context: Context, size: Rectangle];
Lighting
SetAmbientLight: PROC [context: Context, rgb: RGB];
Set the ambient lighting for context.
NameAmbientLight: PROC [context: Context, color: ROPE];
Set ambient light color using color naming scheme
GetAmbientLight: PROC [context: Context] RETURNS [RGB];
Return the ambient lighting for context.
AddLight: PROC [context: Context, name: ROPE, position: Triple, color: RGB ← [1, 1, 1]];
Install a new light source in the scene, or change a previously named one.
DeleteLight: PROC [context: Context, name: ROPE];
Remove an existing light source from the scene
Background
NameBackgroundColor: PROC [context: Context, color: ROPE];
Set background color using color naming scheme
SetBackgroundColor: PROC [context: Context, color: RGB];
Set background color
GetBackgroundColor: PROC [context: Context] RETURNS [color: RGB];
Return the background for context.
SetBackgroundImage: PROC [context: Context, aisFile: ROPE];
Use named AIS file as background image for scene instead of solid color
GetBackgroundImage: PROC [context: Context] RETURNS [ROPE];
Return the name of the background image (NIL if none).
SetBackgroundContext: PROC [context, bkGrdCtx: Context];
Use named 3d context as background image for scene (contexts may be stacked arbitrarily).
KillBackground: PROC [context: Context];
Enable the background or not; over-rides background color or background image.
Shapes
RenderStyle:  TYPE ~ {faceted, smooth, lines, shadedLines, hiddenLines, linesWnormals};
AddShape: PROC [context: Context, shape: Shape];
Add a shape to the context.
AddShapeFromFile: PROC [
context: Context,
shapeName: ROPE,
fileName: ROPE,
position: Triple ← [0.0, 0.0, 0.0]];
Convenience function for reading in a shape from a file and positioning it in a scene;
clones previously read shape if file has been used before.
FindShape: PROC [context: Context, shapeName: ROPE] RETURNS [Shape];
Return the named shape; if context = NIL or shapeName doesn't exist, return NIL.
ShapeFromRope: PROC [
name: ROPE ← NIL,
message: ROPE,
color: ROPE ← NIL,
size: REAL ← 0.5,
font: ROPE ← NIL]
RETURNS [Shape];
Build a shape to display a message within the scene.
Shape is two-dimensional, always facing the eyepoint, but changes in size with perspective.
ChangeRopeMessage: PUBLIC PROC [context: Context, shapeName: ROPE, newMessage: ROPE];
Changes the message displayed for a rope shape
DeleteShape: PROC [context: Context, shapeName: ROPE];
Removes a shape from a context
DeleteAllShapes: PROC [context: Context];
Delete all shapes (whose name does not begin with "Light") from context.
SetRenderStyle: PROC [shape: Shape, renderStyle: RenderStyle];
Change the rendering style for a shape.
SetShininess: PROC [shape: Shape, shininess: REAL];
Set the shape's shininess.
SetColor: PROC [shape: Shape, color: RGB];
Set the color for the given shape.
SetTransmittance: PROC [shape: Shape, transmittance: REAL];
Change the transmittance of the shape; transmittance = 0 is opaque.
N.B: Rendering of transparent objects occurs only when anti-aliasing is enabled.
SetInvisible: PROC [shape: Shape];
Maintain data but don't display the shape.
SetVisible: PROC [shape: Shape];
Undo SetInvisible.
ShowBackfaces: PROC [shape: Shape];
Render back-facing polygons (for transparent or non-closed shapes, or debugging).
HideBackfaces: PROC [shape: Shape];
Don't render back-facing polygons (for transparent or non-closed shapes, or debugging).
Convenient access to internal structures supporting rendering
RenderDataFrom: PROC [shape: Shape] RETURNS [REF RenderData];
ShapeClassFrom: PROC [shape: Shape] RETURNS [REF ShapeClass];
Return the shapeClass for this shape.
ShadingClassFrom: PROC [shape: Shape] RETURNS [REF ShadingClass];
Return the shadingClass for this shape.
PatchesFrom: PROC [shape: Shape] RETURNS [PatchSequence];
Get shape.renderData.patch, the patch-by-patch description, of the surface, conveniently.
Textures 
TextureStyle: TYPE ~ {none, intensity, color, bump, function};
TextureInfo: TYPE ~ RECORD [name: ROPE, type: TextureStyle, filtered: BOOL];
SetTextureMap: PROC [
context: Context,
shapeName: ROPE,
aisName: ROPE,
textureStyle: TextureStyle ← intensity,
textureFiltering: BOOL ← FALSE]
RETURNS [error: ROPE];
Read in the appropriate texture map for the given shape.
Uses summed area tables if textureFiltering, else point sampling.
OffsetTextureCoords: PROC [shape: Shape, offset: Pair];
Offset the texture coordinates for the given shape.
GetTexture: PROC [shape: Shape] RETURNS [PairSequence];
Return the texture coordinates associated with shape.
GetTextureInfo: PROC [shape: Shape] RETURNS [LIST OF TextureInfo];
Return a list of texture information associated with the shape.
ScaleTexture: PROC [context: Context, shape: Shape, scale: Pair];
Scale the texture coordinates associated with shape.
SetTextureScale: PROC [shape: Shape, scale: Pair ← [1.0, 1.0]];
Set the texture scale for the given shape.
GetTextureScale: PROC [shape: Shape] RETURNS [Pair ← [1.0, 1.0]];
Return the texture scale for the given shape.
SetTextureRange: PROC [shape: Shape, textureRange: Pair];
Permits circumvention of seam matching in MappedAndSolidTexture.AdjustTexture.
textureRange should exceed twice the texture range for all polygons in shape.
SetTextureFiltering: PROC [context: Context, shape: Shape, on: BOOL];
Turn on/off the texture filtering for the given shape.
GetBumpScale: PROC [shape: Shape] RETURNS [REAL];
Return the bump scale factor for the given shape.
SetBumpScale: PROC [shape: Shape, scale: REAL ← 1.0];
Set the bump scale factor for this shape.
Rendering
DisplayMode: TYPE ~ {gray, dither, fullColor};
StartLog: PROC [context: Context] RETURNS[IO.STREAM];
open typescript log
FlushLog: PROC [context: Context];
for safety from potential disasters    
CloseLog: PROC [context: Context];
close when done to flush
Render: PROC [context: Context, fork: BOOL ← TRUE];
Perform the rendering process.
WaitTilRenderDone: PROC;
Wait until a rendering process finishes.
NotRendering: PROC [context: Context] RETURNS [BOOL];
Return true iff context is not forked or not rendering.
AbortRender: PROC [context: Context];
Abort any current rendering within context.
GetDisplayMode: PROC [context: Context] RETURNS [DisplayMode];
Return the display mode.
SetAntiAliasing: PROC [context: Context, on: BOOL ← TRUE];
This will draw images using the alpha buffer; texture mapping is enabled.
AntiAliasingNeeded: PROC [context: Context] RETURNS [BOOL];
Determine if anti-aliasing is needed to render the shapes in their respective shading modes.
For example, anti-aliasing is necessary for bump-mapping, transparency, solid texture.
GetBuffer: PROC [context: Context, type: ATOM] RETURNS [SampleMap];
Get a sample map from the context; returns NIL if no such map.
GetAlphaBuffer: PROC [context: Context] RETURNS [SampleMap];
Get the alpha buffer from the context; returns NIL if no such buffer.
GetDepthBuffer: PROC [context: Context] RETURNS [SampleMap];
Get the depth buffer from the context; returns NIL if no such buffer.
Miscellany
PrependWorkingDirectory: PUBLIC PROC[context: Context, file: ROPE] RETURNS[ROPE];
TackOnExtension: PUBLIC PROC[file, extension: ROPE] RETURNS[ROPE];
IntersectRectangles: PROC [Rectangle, Rectangle] RETURNS [Rectangle];
Return intersection (overlapping) portion of combined rectangles.
AtomFromTextureStyle: PROC [textureStyle: TextureStyle] RETURNS [ATOM];
Return an atom for non-typed operations.
AtomFromDisplayMode: PROC [displayMode: DisplayMode] RETURNS [ATOM];
Return an atom for non-typed operations.
RopeFromDisplayMode: PROC [displayMode: DisplayMode] RETURNS [ROPE];
Return the rope representing displayMode.
RopeFromRenderStyle: PROC [renderStyle: RenderStyle] RETURNS [ROPE];
Return the rope representing renderStyle.
RopeFromTextureStyle: PROC [textureStyle: TextureStyle] RETURNS [ROPE];
Return the rope representing textureStyle.
END.