PolygonPen.mesa

Michael Plass, December 8, 1982 10:10 am

DIRECTORY

This module provides for the conversion of pen-drawn spline curves to spline-bounded outlines. The simplest kind of pen handled here is the broad pen, which is just a line segment. Polygonal-pen strokes are built up by means of multiple broad-pen strokes.

PolygonPen: DEFINITIONS =

BEGIN

Pen: TYPE = REF PenRec;

PenRec: TYPE = RECORD[point: SEQUENCE n:NAT OF Vector.Vec];

Bezier: TYPE = CGCubic.Bezier; -- RECORD[b0,b1,b2,b3: Vec];

Vec: TYPE = Vector.Vec; -- RECORD[x,y: REAL];

a broad pen is represented as a vector, with the reference point at the origin.

The results are sent by calling procedures of the following types:

MoveToProc: TYPE = PROCEDURE [z0: Vec];

LineToProc: TYPE = PROCEDURE [z1: Vec];

CurveToProc: TYPE = PROCEDURE [z1, z2, z3: Vec]; -- three Bezier control points. z3 is the new last point.

SimpleStroke: PROCEDURE [pen: Vec, curve: Bezier, moveTo: MoveToProc, lineTo:LineToProc, curveTo:CurveToProc]; -- for when the interior of the curve is known never to be parallel to the pen

BroadStroke: PROCEDURE [pen: Vec, curve: Bezier, moveTo: MoveToProc, lineTo:LineToProc, curveTo:CurveToProc]; -- for a compound stroke with a broad pen.

Dot: PROCEDURE [pen: Pen, point: Vector.Vec, moveTo: MoveToProc, lineTo:LineToProc, curveTo:CurveToProc];

Line: PROCEDURE [pen: Pen, startPoint,endPoint: Vector.Vec, moveTo: MoveToProc, lineTo:LineToProc, curveTo:CurveToProc];

Stroke: PROCEDURE [pen: Pen, curve: Bezier, moveTo: MoveToProc, lineTo:LineToProc, curveTo:CurveToProc];

END.