
DIRECTORY G3dBasic, G3dBox, G3dNats, G3dShape, G3dPlane;

G3dClipVolume: CEDAR DEFINITIONS
~ BEGIN
Box:						TYPE ~ G3dBox.Box;
Plane:						TYPE ~ G3dPlane.Plane;
PlaneSequence:			TYPE ~ G3dPlane.PlaneSequence;
Ray:						TYPE ~ G3dPlane.Ray;
Shape:					TYPE ~ G3dShape.Shape;
Triple:					TYPE ~ G3dBasic.Triple;

ClipVolume:					TYPE ~ REF ClipVolumeRep;
ClipVolumeRep:				TYPE ~ RECORD [
planes:						PlaneSequence ¬ NIL,	-- inward-pointing planes of the volume
box:							Box ¬ []					-- bounding box of the volume
];

TripleList:					TYPE ~ LIST OF Triple;
ClipVolumeFrom4Points: PROC [p0, p1, p2, p3: Triple] RETURNS [ClipVolume];
ShapeInVolume: PROC [shape: Shape, clipVolume: ClipVolume] RETURNS [BOOL];
PolygonInVolume: PROC [pts: TripleList, clipVolume: ClipVolume] RETURNS [BOOL];
NegatePlane: PROC [plane: Plane] RETURNS [Plane];
TripleListFromSurface: PROC [shape: Shape, surfID: INT] RETURNS [TripleList];
ClipToPlane: PROC [vList: TripleList, plane: Plane] RETURNS [TripleList];

END.

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G3dClipVolume.mesa
Copyright Ó 1984, 1992 by Xerox Corporation. All rights reserved.
Glassner, February 18, 1991 9:27 pm PST
Jules Bloomenthal August 26, 1992 3:12 pm PDT
Basic Types
Local Types
Note: This interface is designed to clip convex polygons against convex clipping volumes.  
Clip Volume Construction 
Build a tetrahedral clipping volume from the four points.  
Shape and Polygon Testing 
Returns TRUE if any surface in the shape is within the ClipVolume

Returns TRUE if the polygon represented by pts is within the ClipVolume
Utility
Return the plane with opposite normal and adjusted offset

Return the TripleList describing this surface
Volume Clipping
The basic routine in this interface: return the TripleList resulting by clipping the input TripleList against the plane.
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