Copyright © 1986 by Xerox Corporation. All rights reserved.

Last edited by Bier on June 23, 1986

Contents: The regular polygons and other commonly requested shapes.

Pier, April 24, 1987 0:10:21 am PDT

Bier, February 18, 1987 11:04:00 pm PST

GGBasicTypes, GGBoundBox, GGBuiltinShapes, GGModelTypes, GGOutline, GGSegment, GGSegmentTypes, GGTransform, GGSlice, GGTraj, Vectors2d, ImagerColor, RealFns, Rope;

IMPORTS GGBoundBox, GGOutline, GGSegment, GGSlice, GGTraj, GGTransform, Vectors2d, ImagerColor, RealFns

EXPORTS GGBuiltinShapes = BEGIN

DefaultData: TYPE = GGModelTypes.DefaultData;

Outline: TYPE = GGModelTypes.Outline;

Point: TYPE = GGBasicTypes.Point;

Segment: TYPE = GGSegmentTypes.Segment;

SegmentGenerator: TYPE = GGModelTypes.SegmentGenerator;

Slice: TYPE = GGModelTypes.Slice;

SliceDescriptor: TYPE = GGModelTypes.SliceDescriptor;

Traj: TYPE = GGModelTypes.Traj;

Vector: TYPE = GGBasicTypes.Vector;

The bottom-most edge of the returned polygon will be horizontal. The polygon will be inscribed inside the circle with radius "radius" centered at "origin".

traj: Traj;

theta0, theta, deltaTheta, sin, cos: REAL;

lastPoint, thisPoint: Point;

success: BOOL;

seg: Segment;

deltaTheta ← 360.0/sideCount;

theta0 ← -90.0 + deltaTheta/2.0;

sin ← RealFns.SinDeg[theta0];

cos ← RealFns.CosDeg[theta0];

thisPoint ← Vectors2d.Add[Vectors2d.Scale[[cos, sin], radius], origin];

traj ← GGTraj.CreateTraj[thisPoint];

lastPoint ← thisPoint;

FOR i: NAT IN [1..sideCount-1] DO

sin ← RealFns.SinDeg[theta0];

cos ← RealFns.CosDeg[theta0];

thisPoint ← Vectors2d.Add[Vectors2d.Scale[[cos, sin], radius], origin];

seg ← GGSegment.MakeLine[lastPoint, thisPoint, NIL];

GGSegment.SetDefaults[seg, defaults];

GGTraj.CloseWithSegment[traj, seg, lo];

outline ← GGOutline.CreateOutline[traj, ImagerColor.ColorFromGray[0.5]];

outline.class.setStrokeJoint[outline, outline.class.newParts[outline, NIL, topLevel].parts, defaults.strokeJoint];

outline.class.setFillColor[outline, defaults.fillColor];

};

halfSide: REAL ← sideLength/2.0;

box: GGBoundBox.BoundBox ← GGBoundBox.CreateBoundBox[origin.x-halfSide, origin.y-halfSide, origin.x+halfSide, origin.y+halfSide];

sliceD: SliceDescriptor ← GGSlice.MakeBoxSlice[box, ul, GGTransform.Identity[] ];

completeSliceD: SliceDescriptor ← sliceD.slice.class.newParts[sliceD.slice, NIL, slice];

slice ← sliceD.slice;

GGSlice.SetDefaults[slice, completeSliceD.parts, defaults];

};

outerPoint: Point ← [origin.x + radius, origin.y];

sliceD: SliceDescriptor ← GGSlice.MakeCircleSlice[origin, outerPoint];

completeSliceD: SliceDescriptor ← sliceD.slice.class.newParts[sliceD.slice, NIL, slice];

slice ← sliceD.slice;

GGSlice.SetDefaults[slice, completeSliceD.parts, defaults];

};

The bottom-most edge of the returned polygon will be horizontal. The polygon will be inscribed inside a circle centered at "origin". Each side of the polygon will have length "sideLength".

};

Returns a trajectory with "segmentCount" straight line segments, all of the same length. The entire trajectory is a single straight line, from point p0 to p1. All of its segments are collinear. Knotched lines are useful as rulers.

delta: Vector;

lastPoint, thisPoint: Point;

traj: Traj;

seg: Segment;

success: BOOL;

delta ← Vectors2d.Scale[Vectors2d.Sub[p1, p0], 1.0/segmentCount];

lastPoint ← p0;

traj ← GGTraj.CreateTraj[lastPoint];

THROUGH [1..segmentCount-1] DO

thisPoint ← p1;

seg ← GGSegment.MakeLine[lastPoint, thisPoint, NIL];

success ← GGTraj.AddSegment[traj, hi, seg, lo];

IF NOT success THEN SIGNAL Problem[msg: "Couldn't add segment"];

outline ← GGOutline.CreateOutline[traj, ImagerColor.ColorFromGray[0.5]];

};