DIRECTORY GGBasicTypes; GGCircles: CEDAR DEFINITIONS = BEGIN Arc: TYPE = GGBasicTypes.Arc; Circle: TYPE = GGBasicTypes.Circle; Point: TYPE = GGBasicTypes.Point; Edge: TYPE = GGBasicTypes.Edge; Line: TYPE = GGBasicTypes.Line; Vector: TYPE = GGBasicTypes.Vector; CreateEmptyCircle: PROC [] RETURNS [circle: Circle]; CopyCircle: PROC [from: Circle, to: Circle]; FillCircleFromPointAndRadius: PROC [pt: Point, radius: REAL, circle: Circle]; CircleFromPointAndRadius: PROC [pt: Point, radius: REAL] RETURNS [circle: Circle]; FillCircleFrom3Points: PROC [p0, p1, p2: Point, circle: Circle] RETURNS [linear: BOOL]; CircleFrom3Points: PROC [p0, p1, p2: Point] RETURNS [circle: Circle, linear: BOOL]; CircleMeetsLine: PROC [circle: Circle, line: Line] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; CircleMeetsEdge: PROC [circle: Circle, edge: Edge] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; CircleMeetsCircle: PROC [circle1, circle2: Circle] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; CircleMeetsArc: PROC [circle: Circle, arc: Arc] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; ArcMeetsLine: PROC [arc: Arc, line: Line] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; ArcMeetsEdge: PROC [arc: Arc, edge: Edge] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; ArcMeetsArc: PROC [arc1, arc2: Arc] RETURNS [points: ARRAY [1..2] OF Point, hitCount: [0..2]]; SignedCircleDistance: PROC [pt: Point, circle: Circle] RETURNS [d: REAL]; CircleDistance: PROC [pt: Point, circle: Circle] RETURNS [d: REAL]; PointProjectedOntoCircle: PROC [pt: Point, circle: Circle] RETURNS [projectedPt: Point]; CreateEmptyArc: PROC RETURNS [arc: Arc]; CopyArc: PROC [from: Arc, to: Arc]; FillArc: PROC [v0, v1, v2: Point, arc: Arc]; CreateArc: PROC [v0, v1, v2: Point] RETURNS [arc: Arc]; CirclePointOnArc: PROC [pt: Point, arc: Arc] RETURNS [BOOL]; NearestEndpoint: PROC [pt: Point, arc: Arc] RETURNS [endpoint: Point]; DistanceSquaredToNearestEndpoint: PROC [pt: Point, arc: Arc] RETURNS [distanceSquared: REAL]; NearestPointOnArc: PROC [pt: Point, arc: Arc] RETURNS [onArc: Point]; DistancePointToArc: PROC [pt: Point, arc: Arc] RETURNS [distance: REAL]; DistanceSquaredPointToArc: PROC [pt: Point, arc: Arc] RETURNS [distanceSquared: REAL]; OnArc: PROC [pt: Point, arc: Arc] RETURNS [BOOL]; END. GGCircles.mesa Author: Eric Bier on June 4, 1985 4:58:33 pm PDT Last edited by Bier on January 5, 1987 7:57:14 pm PST Contents: Routines for finding the intersections of various types of circles, lines, and points. Pier, December 6, 1985 10:01:18 am PST Circles Since circles are fairly large data structures, you may prefer to allocate one with CreateEmptyCircle and repeatedly fill it with new data instead of allocating a new one each time. "circle" now has center at "pt" and radius of "radius". Returns a circle with center at "pt" and radius of "radius". "circle" now passes through the three points. If the points are roughly collinear, creates a large circle passing through p0 and p2. Returns a circle which passes through the three points. If the points are roughly collinear, creates a large circle passing through p0 and p2. We drop a normal from the point onto the line and find where it hits the line equation of the normal we drop can be found as in FillLineAsNormal above. Finds any old point on line and returns it. Returns the direction vector of line. Arcs Assumes pt is on arc.circle. Is it on arc? The nearest point on arc.circle to pt, if the nearest point is on arc. Otherwise, the nearest endpoint. Distance[pt, NearestPointOnArc[pt, arc]]. Κh˜Icode™Kšœ0™0Kšœ5™5šœa™aK™&—K˜šΟk ˜ Kšœ ˜ —K˜Kšœ œ œ˜Kš˜K˜Kšœœ˜Kšœœ˜#Kšœœ˜!Kšœœ˜Kšœœ˜šœœ˜#K˜K˜—K™K™K˜KšΟnœœœ˜4Kšž œœ˜-˜Kšœ΅™΅K™—šžœœœ˜NKšœ7™7—šžœœœœ˜SKšœ<™<—K˜šžœœ&œ œ˜XK™…—šžœœœœ˜SKšœ™—K˜K˜Kš žœœœ œœ˜nKš žœœœ œœ˜nKš žœœœ œœ˜nKš žœœœ œœ˜jKš ž œœœ œœ˜dKš ž œœœ œœ˜dKš ž œœœ œœ˜^K˜Kšžœœœœ˜JKšžœœœœ˜Dšžœœœ˜YšœD™DKšœR™R—K™+K™%K˜—K™K™K˜Kšžœœœ ˜)Kšžœœ˜$K˜Kšžœœ ˜-Kšž œœœ ˜8K˜šžœœœœ˜=Kšœ+™+—Kšžœœœ˜GKšž œœœœ˜]šžœœœ˜EKšœh™hK™—šžœœœ œ˜IKšœ)™)—Kšžœœœœ˜WKšžœœœœ˜1K™Kšœ˜K˜—…— NΈ