DIRECTORY
AtomButtons, AtomButtonsTypes, CubicPaths, Feedback, GList, GGBasicTypes, GGContainer, GGFont, GGInterfaceTypes, GGModelTypes, GGSegment, GGSegmentTypes, GGSequence, GGSlice, GGUserInput, Imager, ImagerPath, ImagerTransformation, Match, MatchTurtle, MatchViewer, RealFns, SlackProcess, Vectors2d, ViewerClasses;

MatchTurtleImpl: CEDAR PROGRAM
IMPORTS AtomButtons, CubicPaths, GList, GGSegment, GGSequence, GGSlice, ImagerPath, ImagerTransformation, MatchViewer, RealFns, Vectors2d
EXPORTS MatchTurtle = BEGIN

MatchData: TYPE = MatchViewer.MatchData;
PositionDescriptor: TYPE = MatchTurtle.PositionDescriptor;
PositionDObj: TYPE = MatchTurtle.PositionDObj;
Matcher: TYPE = MatchTurtle.Matcher;
MatcherObj: TYPE = MatchTurtle.MatcherObj;
Point: TYPE = GGBasicTypes.Point;
Segment: TYPE = GGSegmentTypes.Segment;
SegmentGenerator: TYPE = GGModelTypes.SegmentGenerator;
Slice: TYPE = GGModelTypes.Slice;
TurtleHeader: TYPE = MatchTurtle.TurtleHeader;
TurtleHeaderObj: TYPE = MatchTurtle.TurtleHeaderObj;
TurtleInfo: TYPE = MatchTurtle.TurtleInfo;
TurtleInfoObj: TYPE = MatchTurtle.TurtleInfoObj;
Traj: TYPE = GGModelTypes.Traj;
smallNumber: REAL = 1.0e-20; -- for divide by zero checks



GetShapeOfSlice: PUBLIC PROC [slice: Slice] RETURNS [TurtleHeader] = {
RETURN [
SELECT slice.class.type FROM
$Box => BoxToTurtle[slice],
$Circle => CircleToTurtle[slice],
$Text => TextToTurtle[slice],
$Outline => ERROR, -- This routine should not be called for outlines
ENDCASE => NIL -- for slices without real shape (eg. IP)
];
};

TrajToTurtle: PUBLIC PROC [traj: Traj] RETURNS [turtle: TurtleHeader] = {
AppendTurtleSeg: GGModelTypes.WalkProc = {
tail _ SegmentToTurtle[seg, tail];
};
tail: LIST OF TurtleInfo _ NIL;
WalkSegmentsInTraj[traj, AppendTurtleSeg];
turtle _ PackageTurtleTail[tail];
};

WalkSegmentsInTraj: PROC [traj: Traj, walkProc: GGModelTypes.WalkProc] = {
segGen: SegmentGenerator _ GGSequence.SegmentsInTraj[traj];
FOR seg: Segment _ GGSequence.NextSegment[segGen], GGSequence.NextSegment[segGen] UNTIL seg = NIL DO
[] _ walkProc[seg, NIL];
ENDLOOP;
};

SegmentToTurtle: PUBLIC PROC [seg: Segment, soFar: LIST OF TurtleInfo, reverse: BOOL _ FALSE] RETURNS [path: LIST OF TurtleInfo] = {
SELECT seg.class.type FROM
$Line => path _ LineToTurtle[seg.lo, seg.hi, soFar, reverse]; 
$Arc => path _ ArcToTurtle[seg, soFar, reverse];
$Conic => path _ ConicToTurtle[seg, soFar, reverse];
$Bezier => path _ BezierToTurtle[seg, soFar, reverse];
$CubicSpline => path _ CubicSplineToTurtle[seg, soFar, reverse];
ENDCASE => ERROR;
IF path # NIL THEN { -- make sure that path contains seg.hi (or near enough point)
extreme: Point _ IF reverse THEN seg.lo ELSE seg.hi;
dist: REAL _ Vectors2d.DistanceSquared[path.first.end, extreme];
IF dist >= 1.0 THEN path _ CONS[NEW[TurtleInfoObj _ [length: RealFns.SqRt[dist] + path.first.length, start: path.first.end, end: extreme]], path];
}
ELSE path _ LIST[NEW[TurtleInfoObj _ [length: Vectors2d.Distance[seg.lo, seg.hi], start: IF reverse THEN seg.hi ELSE seg.lo, end: IF reverse THEN seg.lo ELSE seg.hi]]]; -- make sure path # NIL on return (seg may be too small to register)
};
CopyTurtleTail: PUBLIC PROC [turtleTail: LIST OF TurtleInfo] RETURNS [newTail: LIST OF TurtleInfo _ NIL] = {
FOR list: LIST OF TurtleInfo _ turtleTail, list.rest UNTIL list=NIL DO
newTail _ CONS[NEW[TurtleInfoObj _ list.first^], newTail];
ENDLOOP;
newTail _ NARROW[GList.DReverse[newTail], LIST OF TurtleInfo];
};


PackageTurtleTail: PUBLIC PROC [tail: LIST OF TurtleInfo] RETURNS [turtle: TurtleHeader] = {
turtle _ NEW[TurtleHeaderObj];
turtle.length _ tail.first.length; -- note tail is backwards here
turtle.tail _ NARROW[GList.Reverse[tail], LIST OF TurtleInfo];
turtle.center _ turtle.originalCenter _ FindCenterOfMass[turtle.tail];
turtle.closed _ IsEssentiallyClosed[turtle.tail];
turtle.radius _ MaxDistanceToTurtle[turtle.tail, turtle.center];
turtle.originalStart _ turtle.tail.first.start;
IF turtle.closed THEN turtle _ FindCanonicalStart[turtle];
turtle _ NormalizeTurtle[turtle]; -- converts the turtle to a canonical form, based upon current rotation or scale invariance
};

MaxDistanceToTurtle: PROC [turtleList: LIST OF TurtleInfo, point: Point] RETURNS [maxDist: REAL] = {
maxDist _ Vectors2d.DistanceSquared[point, turtleList.first.start];
FOR turtleList _ turtleList, turtleList.rest UNTIL turtleList=NIL DO
newDist: REAL _ Vectors2d.DistanceSquared[point, turtleList.first.end];
IF newDist > maxDist THEN maxDist _ newDist;
ENDLOOP;
maxDist _ RealFns.SqRt[maxDist];
};


CopyTurtle: PROC [turtle: TurtleHeader] RETURNS [newTurtle: TurtleHeader] = {
newTurtle _ NEW[TurtleHeaderObj _ turtle^];
newTurtle.tail _ CopyTurtleTail[turtle.tail];
};

CopyTurtleInPlace: PROC [original, storage: TurtleHeader] RETURNS [TurtleHeader] = {
copyTail: LIST OF TurtleInfo _ storage.tail;
originalTail: LIST OF TurtleInfo _ original.tail;
storage^ _ original^;
FOR list: LIST OF TurtleInfo _ copyTail, list.rest UNTIL list=NIL DO
list.first^ _ originalTail.first^;
originalTail _ originalTail.rest;
ENDLOOP;
storage.tail _ copyTail;
RETURN[storage];
};

NormalizeTurtle: PROC [turtle: TurtleHeader] RETURNS [TurtleHeader] = {
turtleList: LIST OF TurtleInfo _ turtle.tail;
targetLength: REAL = 500.0;
matchData: MatchData _ MatchViewer.GetMatchData[];
firstLoop: BOOL _ TRUE;
scaleFactor: REAL _ 1.0;
IF turtleList=NIL THEN RETURN[NIL]
ELSE {
transform: ImagerTransformation.Transformation;
transform _ ImagerTransformation.Translate[[-turtleList.first.start.x, -turtleList.first.start.y]];
IF AtomButtons.GetBinaryState[matchData.rotationInv] THEN {
angle: REAL _ Vectors2d.AngleFromVector[Vectors2d.Sub[turtle.center, turtleList.first.start]];
ImagerTransformation.ApplyPostRotate[transform, -angle];
};
IF AtomButtons.GetBinaryState[matchData.scaleInv] THEN {
length: REAL _ NARROW[GList.NthElement[turtleList, -1], TurtleInfo].length;
scaleFactor _ IF length < 1.0 THEN 1.0 ELSE targetLength / length;
ImagerTransformation.ApplyPostScale[transform, scaleFactor];
};
FOR tList: LIST OF TurtleInfo _ turtleList, tList.rest UNTIL tList=NIL DO
IF firstLoop THEN {
tList.first.start _ ImagerTransformation.Transform[transform, tList.first.start];
firstLoop _ FALSE;
};
tList.first.end _ ImagerTransformation.Transform[transform, tList.first.end];
tList.first.length _ tList.first.length * scaleFactor;
IF tList.rest#NIL THEN tList.rest.first.start _ tList.first.end; -- this end = next start
ENDLOOP;
turtle.length _ turtle.length * scaleFactor;
turtle.radius _ turtle.radius * scaleFactor;
turtle.center _ ImagerTransformation.Transform[transform, turtle.center];
IF turtle.tform = NIL THEN turtle.tform _ transform
ELSE turtle.tform _ ImagerTransformation.Concat[turtle.tform, transform];
};
RETURN[turtle];
};

SetStartClosedTurtle: PROC [original: TurtleHeader, newStart: LIST OF TurtleInfo, storage: TurtleHeader] RETURNS [TurtleHeader] = {
oldStart, firstEnd, secondEnd: LIST OF TurtleInfo;
storage _ CopyTurtleInPlace[original, storage];
IF original.tail=newStart THEN RETURN [storage];
oldStart _ firstEnd _ storage.tail;
FOR list: LIST OF TurtleInfo _ original.tail, list.rest UNTIL list.rest=newStart DO
firstEnd _ firstEnd.rest;
ENDLOOP;
newStart _ firstEnd.rest; -- replace newStart with its analog on the copy
firstEnd.rest _ NIL; -- splice into two lists
FOR list: LIST OF TurtleInfo _ newStart, list.rest UNTIL list=NIL DO -- adjust lengths of newStart
list.first.length _ list.first.length - firstEnd.first.length;
secondEnd _ list;
ENDLOOP;
FOR list: LIST OF TurtleInfo _ oldStart, list.rest UNTIL list=NIL DO -- adjust lengths of oldStart
list.first.length _ list.first.length + secondEnd.first.length;
ENDLOOP;
secondEnd.rest _ oldStart; -- combine the two fragments
storage.tail _ newStart;
storage.originalStart _ ImagerTransformation.InverseTransform[original.tform, newStart.first.start];
RETURN[storage];
};
FindCenterOfMass: PROC [turtleList: LIST OF TurtleInfo] RETURNS [center: Point] = {
lastLength, xSum, ySum: REAL _ 0.0;
FOR turtleList _ turtleList, turtleList.rest UNTIL turtleList=NIL DO
length: REAL _ turtleList.first.length - lastLength;
xSum _ xSum + ((turtleList.first.start.x + turtleList.first.end.x) / 2.0) * length;
ySum _ ySum + ((turtleList.first.start.y + turtleList.first.end.y) / 2.0) * length;
lastLength _ turtleList.first.length;
ENDLOOP;
RETURN [[xSum/lastLength, ySum/lastLength]];
};

IsEssentiallyClosed: PROC [turtleList: LIST OF TurtleInfo] RETURNS [BOOL _ FALSE] = {
firstInfo, lastInfo: TurtleInfo;
IF turtleList = NIL OR turtleList.rest = NIL THEN RETURN [FALSE]; -- length must be > 2
firstInfo _ NARROW[GList.NthElement[turtleList, 1], TurtleInfo];
lastInfo _ NARROW[GList.NthElement[turtleList, -1], TurtleInfo];
IF ABS[lastInfo.end.x - firstInfo.start.x] + ABS[lastInfo.end.y - firstInfo.start.y] < 1.0 THEN RETURN [TRUE];
};

RealEqual: PROC [r1, r2: REAL, epsilon: REAL _ 1.0e-6] RETURNS [BOOL] = {
IF ABS[r1-r2] <= epsilon THEN RETURN[TRUE]
ELSE RETURN[FALSE];
};

FindCanonicalStart: PROC [turtle: TurtleHeader] RETURNS [TurtleHeader] = {
radiusSquared: REAL _ turtle.radius * turtle.radius;
IF NOT CounterClockwise[turtle] THEN turtle _ SimpleFlipTurtle[turtle];
FOR list: LIST OF TurtleInfo _ turtle.tail, list.rest UNTIL list=NIL DO
IF RealEqual[radiusSquared, Vectors2d.DistanceSquared[turtle.center, list.first.start], .1] THEN {
copy: TurtleHeader _ CopyTurtle[turtle];
copy _ SetStartClosedTurtle[turtle, list, copy];
RETURN[copy];
};
ENDLOOP;
ERROR; -- should never reach this return (should increase epsilon in RealEqual call)
};

CounterClockwise: PROC [turtle: TurtleHeader] RETURNS [BOOL] = {
area: REAL _ 0.0;
IF NOT turtle.closed THEN ERROR;
IF turtle.tail = NIL OR turtle.tail.rest = NIL THEN RETURN[FALSE]; -- degenerate tail (bogus result)
FOR tail: LIST OF TurtleInfo _ turtle.tail, tail.rest UNTIL tail = NIL DO
area _ area + tail.first.start.x * tail.first.end.y - tail.first.start.y * tail.first.end.x;
ENDLOOP;
RETURN[area < 0.0];
};


CircleToTurtle: PROC [slice: Slice] RETURNS [turtle: TurtleHeader] = {
p0, p1, p2, p3, center, outerPoint: Point;
transform: ImagerTransformation.Transformation;
dummyArc: Segment;
dist: REAL;
[center, outerPoint, transform] _ GGSlice.CircleGetParams[slice];
turtle _ NEW[TurtleHeaderObj];
p0 _ ImagerTransformation.Transform[transform, [0.0, 1.0]];
p1 _ ImagerTransformation.Transform[transform, [1.0, 0.0]];
p2 _ ImagerTransformation.Transform[transform, [0.0, -1.0]];
p3 _ ImagerTransformation.Transform[transform, [-1.0, 0.0]];
dummyArc _ GGSegment.MakeArc[p0, p1, p2, NIL]; -- may be a tad inefficient, but saves code
turtle.tail _ ArcToTurtle[dummyArc, NIL];
dummyArc _ GGSegment.MakeArc[p2, p3, p0, NIL];
turtle.tail _ ArcToTurtle[dummyArc, turtle.tail];
dist _ Vectors2d.Distance[p0, turtle.tail.first.end]; -- maybe should check for empty tail?
IF dist >= 1.0 THEN turtle.tail _ CONS[NEW[TurtleInfoObj _ [length: dist + turtle.tail.first.length, start: turtle.tail.first.end, end: p0]], turtle.tail];
turtle.length _ turtle.tail.first.length; -- note turtle.tail is backwards here
turtle.tail _ NARROW[GList.DReverse[turtle.tail], LIST OF TurtleInfo]; -- put in proper order
turtle.center _ turtle.originalCenter _ center;
turtle.closed _ TRUE;
turtle.radius _ Vectors2d.Distance[center, outerPoint];
turtle.originalStart _ turtle.tail.first.start;
IF NOT CounterClockwise[turtle] THEN turtle _ SimpleFlipTurtle[turtle]; -- would normally be handled in FindCanonicalStart, but it would be overkill to call that for circles
turtle _ NormalizeTurtle[turtle];
};

BoxToTurtle: PROC [slice: Slice] RETURNS [turtle: TurtleHeader] = {
lastHi: Point;
dist: REAL;
AppendTurtleSeg: GGModelTypes.WalkProc = {
lastHi _ ImagerTransformation.Transform[transform, seg.hi];
turtle.tail _ LineToTurtle[ImagerTransformation.Transform[transform, seg.lo], lastHi, turtle.tail];
};
turtle _ NEW[TurtleHeaderObj];
turtle.tail _ NIL;
[] _ GGSlice.WalkSegments[slice, AppendTurtleSeg];
dist _ Vectors2d.Distance[lastHi, turtle.tail.first.end];
IF dist >= 1.0 THEN turtle.tail _ CONS[NEW[TurtleInfoObj _ [length: dist + turtle.tail.first.length, start: turtle.tail.first.end, end: lastHi]], turtle.tail];
turtle.length _ turtle.tail.first.length; -- note turtle.tail is backwards here
turtle.tail _ NARROW[GList.DReverse[turtle.tail], LIST OF TurtleInfo]; -- put in proper order
turtle.center _ turtle.originalCenter _ FindCenterOfMass[turtle.tail];
turtle.closed _ TRUE;
turtle.radius _ MaxDistanceToTurtle[turtle.tail, turtle.center];
turtle.originalStart _ turtle.tail.first.start;
turtle _ FindCanonicalStart[turtle];
turtle _ NormalizeTurtle[turtle]; -- converts the turtle to a canonical form, based upon current rotation or scale invariance
};

TextToTurtle: PROC [slice: Slice] RETURNS [turtle: TurtleHeader] = {
entireD: GGModelTypes.SliceDescriptor _ slice.class.newParts[slice, NIL, slice];
pointGen: GGModelTypes.PointGenerator _ slice.class.pointsInDescriptor[entireD];
lowerLeft: GGModelTypes.PointAndDone _ slice.class.nextPoint[pointGen];
lowerRight: GGModelTypes.PointAndDone;
THROUGH [1..7] DO
[] _ slice.class.nextPoint[pointGen];
ENDLOOP;
lowerRight _ slice.class.nextPoint[pointGen];
IF lowerLeft.done OR lowerRight.done THEN ERROR;
turtle _ PackageTurtleTail[LineToTurtle[lowerLeft.point, lowerRight.point, NIL]];
};

LineToTurtle: PROC [lo, hi: Point, soFar: LIST OF TurtleInfo, reverse: BOOL _ FALSE] RETURNS [path: LIST OF TurtleInfo] = { -- slightly different calling sequence required (called from additional places)
length: REAL _ Vectors2d.Distance[lo, hi];
IF length < epsilon/2.0 THEN RETURN[soFar];
IF soFar#NIL THEN length _ length + soFar.first.length;
path _ CONS[NEW[TurtleInfoObj _ [length: length, start: IF reverse THEN hi ELSE lo, end: IF reverse THEN lo ELSE hi]], soFar];
};

ArcToTurtle: PROC [seg: Segment, soFar: LIST OF TurtleInfo, reverse: BOOL _ FALSE] RETURNS [LIST OF TurtleInfo] = {
ConicTo: ImagerPath.ConicToProc = {
ImagerPath.ConicToCurves[lastConicP0, p1, p2, r, BreakUpBezier];
lastConicP0 _ p2;
};
BreakUpBezier: ImagerPath.CurveToProc = {
path: CubicPaths.Path _ NEW[CubicPaths.PathRec];
path.cubics _ NEW[CubicPaths.PathSequence[1]];
path.cubics[0] _ [lastBezierP0, p1, p2, p3];
CubicPaths.UpdateBounds[path];
CubicPaths.WalkPath[path, epsilon, PointProc];
lastBezierP0 _ p3;
};
PointProc: CubicPaths.PointProc = {
start: Point _ IF soFar=NIL THEN p0 ELSE soFar.first.end;
length: REAL _ Vectors2d.Distance[p, start];
IF length < epsilon/2.0 THEN RETURN;
IF soFar#NIL THEN length _ length + soFar.first.length;
soFar _ CONS[NEW[TurtleInfoObj _ [length: length, start: start, end: p]], soFar];
};
p0, p1, p2, lastConicP0, lastBezierP0: Point;
IF reverse THEN [p2, p1, p0] _ GGSegment.ArcGetParams[seg]
ELSE [p0, p1, p2] _ GGSegment.ArcGetParams[seg];
lastConicP0 _ lastBezierP0 _ p0;
ImagerPath.ArcToConics[p0, p1, p2, ConicTo];
RETURN[soFar];
};

ConicToTurtle: PROC [seg: Segment, soFar: LIST OF TurtleInfo, reverse: BOOL _ FALSE] RETURNS [LIST OF TurtleInfo] = {
BreakUpBezier: ImagerPath.CurveToProc = {
path: CubicPaths.Path _ NEW[CubicPaths.PathRec];
path.cubics _ NEW[CubicPaths.PathSequence[1]];
path.cubics[0] _ [lastBezierP0, p1, p2, p3];
CubicPaths.UpdateBounds[path];
CubicPaths.WalkPath[path, epsilon, PointProc];
lastBezierP0 _ p3;
};
PointProc: CubicPaths.PointProc = {
start: Point _ IF soFar=NIL THEN p0 ELSE soFar.first.end;
length: REAL _ Vectors2d.Distance[p, start];
IF length < epsilon/2.0 THEN RETURN;
IF soFar#NIL THEN length _ length + soFar.first.length;
soFar _ CONS[NEW[TurtleInfoObj _ [length: length, start: start, end: p]], soFar];
};
p0, p1, p2, lastBezierP0: Point;
r: REAL;
IF reverse THEN [p2, p1, p0, r] _ GGSegment.ConicGetParams[seg]
ELSE [p0, p1, p2, r] _ GGSegment.ConicGetParams[seg];
lastBezierP0 _ p0;
ImagerPath.ConicToCurves[p0, p1, p2, r, BreakUpBezier];
RETURN[soFar];
};

BezierToTurtle: PROC [seg: Segment, soFar: LIST OF TurtleInfo, reverse: BOOL _ FALSE] RETURNS [LIST OF TurtleInfo] = {
PointProc: CubicPaths.PointProc = {
start: Point _ IF soFar=NIL THEN p0 ELSE soFar.first.end;
length: REAL _ Vectors2d.Distance[p, start];
IF length < epsilon/2.0 THEN RETURN;
IF soFar#NIL THEN length _ length + soFar.first.length;
soFar _ CONS[NEW[TurtleInfoObj _ [length: length, start: start, end: p]], soFar];
};
p0, p1, p2, p3: Point;
path: CubicPaths.Path _ NEW[CubicPaths.PathRec];
IF reverse THEN [p3, p2, p1, p0] _ GGSegment.BezierGetParams[seg]
ELSE [p0, p1, p2, p3] _ GGSegment.BezierGetParams[seg];
path.cubics _ NEW[CubicPaths.PathSequence[1]];
path.cubics[0] _ [p0, p1, p2, p3];
CubicPaths.UpdateBounds[path];
CubicPaths.WalkPath[path, epsilon, PointProc];
RETURN[soFar];
};

CubicSplineToTurtle: PROC [seg: Segment, soFar: LIST OF TurtleInfo, reverse: BOOL _ FALSE] RETURNS [LIST OF TurtleInfo] = {
PointProc: CubicPaths.PointProc = {
start: Point _ IF soFar=NIL THEN path.cubics[0].b0 ELSE soFar.first.end;
length: REAL _ Vectors2d.Distance[p, start];
IF length < epsilon/2.0 THEN RETURN;
IF soFar#NIL THEN length _ length + soFar.first.length;
soFar _ CONS[NEW[TurtleInfoObj _ [length: length, start: start, end: p]], soFar];
};
path: CubicPaths.Path _ GGSegment.CubicSplineGetParams[seg];
IF reverse THEN CubicPaths.ReversePath[CubicPaths.CopyPath[path]];
CubicPaths.WalkPath[path, epsilon, PointProc];
RETURN[soFar];
};


FlipTurtle: PUBLIC PROC [turtle: TurtleHeader] RETURNS [newTurtle: TurtleHeader] = {
IF NOT turtle.closed THEN newTurtle _ SimpleFlipTurtle[turtle] ELSE newTurtle _ turtle;
newTurtle _ NormalizeTurtle[newTurtle];
};

SimpleFlipTurtle: PROC [turtle: TurtleHeader] RETURNS [newTurtle: TurtleHeader] = {
lastLength, thisLength: REAL _ 0.0;
newTurtle _ CopyTurtle[turtle];
IF turtle.tail # NIL THEN {
FOR tailList: LIST OF TurtleInfo _ newTurtle.tail, tailList.rest UNTIL tailList=NIL DO
temp: Point _ tailList.first.start; -- swap start and end
tailList.first.start _ tailList.first.end;
tailList.first.end _ temp;
thisLength _ tailList.first.length;
tailList.first.length _ turtle.length - lastLength;
lastLength _ thisLength
ENDLOOP;
newTurtle.tail _ NARROW[GList.DReverse[newTurtle.tail], LIST OF TurtleInfo];
newTurtle.originalStart _ ImagerTransformation.InverseTransform[newTurtle.tform, newTurtle.tail.first.start];
};
};


epsilon: REAL = 3.0;
ManhattanDistance: PROC [pt1, pt2: Point] RETURNS [REAL] = {
RETURN[ABS[pt2.x - pt1.x] + ABS[pt2.y - pt1.y]];
};

TurtleEqualEitherWay: PUBLIC PROC [turtle1, turtle2: TurtleHeader, tol: REAL _ MatchViewer.GetMatchTolerance[], posD: PositionDescriptor _ NIL] RETURNS [BOOL] = {
matchData: MatchData _ MatchViewer.GetMatchData[];
IF AtomButtons.GetBinaryState[matchData.polarity] OR turtle1.closed THEN RETURN[TurtleEqual[turtle1, turtle2, tol, posD]]
ELSE {
flipped1: TurtleHeader _ FlipTurtle[turtle1];
RETURN[TurtleEqual[turtle1, turtle2, tol, posD] OR TurtleEqual[flipped1, turtle2, tol, posD]];
};
};

TurtleEqual: PUBLIC PROC [turtle1, turtle2: TurtleHeader, tol: REAL _ MatchViewer.GetMatchTolerance[], posD: PositionDescriptor] RETURNS [BOOL _ FALSE] = {
IF NOT posD.valid THEN {
matcher: Matcher _ CreateMatcher[turtle1, turtle2, tol, TRUE];
next: PositionDescriptor _ NextMatch[matcher];
IF next # NIL THEN {
IF posD.settable THEN {
posD^ _ next^;
posD.others _ matcher; -- return the orientation that achieves the turtle match
};
RETURN[TRUE]; -- we did find an orientation that matches the turtles
}
ELSE RETURN[FALSE];
}
ELSE RETURN[TurtleEqualAux[turtle1, turtle2, tol, posD]];
};

TurtleEqualAux: PUBLIC PROC [turtle1, turtle2: TurtleHeader, tol: REAL _ MatchViewer.GetMatchTolerance[], posD: PositionDescriptor _ NIL] RETURNS [BOOL _ FALSE] = {
maxError: REAL;
IF turtle1 = turtle2 THEN RETURN[TRUE]; -- true if both NIL
IF turtle1 = NIL OR turtle2 = NIL THEN RETURN[FALSE];
IF turtle1.closed # turtle2.closed THEN RETURN[FALSE]; -- closed can never match open
maxError _ tol * (turtle1.length + turtle2.length) / 2.0;
IF ABS[turtle1.radius - turtle2.radius] > maxError THEN RETURN[FALSE];
IF ABS[turtle1.length - turtle2.length] > maxError THEN RETURN[FALSE];
IF NOT turtle1.closed THEN { -- Open turtles are easy
IF OpenTurtleEqual[turtle1, turtle2, maxError, posD] THEN {
SetPosD[posD, turtle1, turtle2];
RETURN[TRUE];
}
ELSE RETURN[FALSE];
}
ELSE { -- Closed turtles may require testing multiple starting points.
matchData: MatchData _ MatchViewer.GetMatchData[];
rotationInv: BOOL _ AtomButtons.GetBinaryState[matchData.rotationInv];
turtleCopy: TurtleHeader _ CopyTurtle[turtle2];
FOR tail2: LIST OF TurtleInfo _ turtle2.tail, tail2.rest UNTIL tail2 = NIL DO
IF NOT rotationInv AND ManhattanDistance[turtle1.center, Vectors2d.Add[turtle2.center, Vectors2d.Sub[turtle1.tail.first.start, tail2.first.start]]] > maxError THEN LOOP; -- reject: not rotation invariant and the centers are far apart
IF ABS[Vectors2d.Distance[turtle2.center, tail2.first.start] - turtle2.radius] < maxError THEN {
turtleCopy _ SetStartClosedTurtle[turtle2, tail2, turtleCopy];
turtleCopy _ NormalizeTurtle[turtleCopy];
IF OpenTurtleEqual[turtle1, turtleCopy, maxError, posD] THEN {
SetPosD[posD, turtle1, turtleCopy];
RETURN[TRUE];
};
};
ENDLOOP;
};
};

SetPosD: PROC [posD: PositionDescriptor, turtle1, turtle2: TurtleHeader] = {
IF posD # NIL AND posD.settable AND NOT posD.valid THEN {
posD.valid _ TRUE;
posD.tform1 _ turtle1.tform;
posD.tform2 _ turtle2.tform;
};
};


GetInterpolatedPoint: PROC [param, lengthSoFar: REAL, t: TurtleInfo] RETURNS [pt: Point] = {
ratio, divisor: REAL;
divisor _ t.length - lengthSoFar;
IF ABS[divisor] < smallNumber THEN RETURN[t.start];
ratio _ (param - lengthSoFar)/divisor;
pt _ Vectors2d.Add[t.start, Vectors2d.Scale[Vectors2d.Sub[t.end, t.start], ratio]];
};

OpenTurtleEqual: PROC [turtle1, turtle2: TurtleHeader, maxError: REAL, posD: PositionDescriptor _ NIL] RETURNS [BOOL _ TRUE] = {
OPEN ImagerTransformation;
length1, length2, maxDist, dist: REAL _ 0.0;
t1: LIST OF TurtleInfo _ turtle1.tail;
t2: LIST OF TurtleInfo _ turtle2.tail;
tailPoint: Point;
IF ManhattanDistance[turtle1.center, turtle2.center] > maxError THEN RETURN[FALSE];
IF posD#NIL AND posD.valid AND (
ManhattanDistance[ -- compare in the posD canonical coordinate frame
Transform[posD.tform1, turtle1.originalStart],
Transform[posD.tform2, turtle2.originalStart]] > 2.0 * maxError
OR ManhattanDistance[
Transform[posD.tform1, turtle1.originalCenter],
Transform[posD.tform2, turtle2.originalCenter]] > 2.0 * maxError)
THEN RETURN [FALSE]; -- (multiplying maxError by 2 since this operation is very conducive to floating point error)
IF t1=NIL OR t2=NIL THEN RETURN[FALSE];
maxDist _ ManhattanDistance[t1.first.start, t2.first.start];
WHILE t1#NIL OR t2#NIL DO
IF t1=NIL THEN { -- take element off t2 (t1 is NIL)
dist _ ManhattanDistance[t2.first.end, tailPoint]; -- tailPoint is last point in exhausted list
maxDist _ MAX[dist, maxDist];
length2 _ t2.first.length;
t2 _ t2.rest;
}
ELSE IF t2=NIL THEN { -- take element off t1 (t2 is NIL)
dist _ ManhattanDistance[t1.first.end, tailPoint]; -- tailPoint is last point in exhausted list
maxDist _ MAX[dist, maxDist];
length1 _ t1.first.length;
t1 _ t1.rest;
}
ELSE { -- t1 and t2 both have elements left
IF t1.first.length < t2.first.length THEN { -- take element off t1
pt: Point _ GetInterpolatedPoint[t1.first.length, length2, t2.first];
dist _ ManhattanDistance[pt, t1.first.end];
maxDist _ MAX[dist, maxDist];
length1 _ t1.first.length;
tailPoint _ t1.first.end;
t1 _ t1.rest;
}
ELSE { -- take element off t2
pt: Point _ GetInterpolatedPoint[t2.first.length, length1, t1.first];
dist _ ManhattanDistance[pt, t2.first.end];
maxDist _ MAX[dist, maxDist];
length2 _ t2.first.length;
tailPoint _ t2.first.end;
t2 _ t2.rest;
};
};
IF maxDist > maxError THEN RETURN [FALSE];
ENDLOOP;
};


CreateMatcher: PUBLIC PROC [turtle1, turtle2: TurtleHeader, tol: REAL _ -1.0, oneWay: BOOL] RETURNS [m: Matcher] = {
m _ NEW[MatcherObj _ [noMatch: TRUE]];
IF turtle1 = turtle2 THEN RETURN; -- no match (bool has been set to TRUE)
IF turtle1 = NIL OR turtle2 = NIL THEN RETURN;
IF turtle1.closed # turtle2.closed THEN RETURN; -- closed can never match open
m.maxError _ tol * (turtle1.length + turtle2.length) / 2.0;
IF ABS[turtle1.radius - turtle2.radius] > m.maxError THEN RETURN;
IF ABS[turtle1.length - turtle2.length] > m.maxError THEN RETURN;
m.turtle1 _ turtle1;
m.turtle2 _ turtle2;
m.tailSoFar _ turtle2.tail;
m.checkFirst _ TRUE;
m.checkSecond _ NOT oneWay; 
m.noMatch _ FALSE;
IF turtle2.closed THEN m.turtleCopy _ CopyTurtle[turtle2]; -- will be used for orientation testing
};

NextMatch: PUBLIC PROC [m: Matcher] RETURNS [PositionDescriptor _ NIL] = {
IF m.noMatch THEN RETURN[NIL];
IF NOT m.turtle1.closed THEN {
IF m.checkFirst THEN {
m.checkFirst _ FALSE;
IF OpenTurtleEqual[m.turtle1, m.turtle2, m.maxError] THEN RETURN[NEW[PositionDObj _ [tform1: m.turtle1.tform, tform2: m.turtle2.tform, valid: TRUE, settable: FALSE, others: m]]];
};
IF m.checkSecond THEN {
flipped1: TurtleHeader _ FlipTurtle[m.turtle1];
m.noMatch _ TRUE; -- no more matches after this
IF OpenTurtleEqual[flipped1, m.turtle2, m.maxError] THEN RETURN[NEW[PositionDObj _ [tform1: flipped1.tform, tform2: m.turtle2.tform, valid: TRUE, settable: FALSE, others: m]]]
};
RETURN[NIL];
}
ELSE { -- we have to test against every possible axis (potentially slow!) until we find a match
matchData: MatchData _ MatchViewer.GetMatchData[];
rotationInv: BOOL _ AtomButtons.GetBinaryState[matchData.rotationInv];
FOR tail2: LIST OF TurtleInfo _ m.tailSoFar, tail2.rest UNTIL tail2 = NIL DO
IF NOT rotationInv AND ManhattanDistance[m.turtle1.center, Vectors2d.Add[m.turtle2.center, Vectors2d.Sub[m.turtle1.tail.first.start, tail2.first.start]]] > m.maxError THEN LOOP; -- an optimization
IF ABS[Vectors2d.Distance[m.turtle2.center, tail2.first.start] - m.turtle2.radius] < m.maxError THEN {
m.turtleCopy _ SetStartClosedTurtle[m.turtle2, tail2, m.turtleCopy];
m.turtleCopy _ NormalizeTurtle[m.turtleCopy];
IF OpenTurtleEqual[m.turtle1, m.turtleCopy, m.maxError] THEN {
m.tailSoFar _ tail2.rest;
RETURN[NEW[PositionDObj _ [tform1: m.turtle1.tform, tform2: m.turtleCopy.tform, valid: TRUE, settable: FALSE, others: m]]];
};
};
ENDLOOP;
};
};


END.
MatchTurtleImpl.mesa
Last edited by: David Kurlander -  September 6, 1987 6:02:03 pm PDT
Bier, September 5, 1987 0:36:34 am PDT
Making Turtles
walks the segments of a trajectory, but unlike most of the segment walk routines, does not return a sequence
Finds the greatest distance from a turtle to a point
Utilities for Making Turtles
Copies one turtle into another (original into storage).  Storage must have the same size tail as original
Translates first point to the origin.  Rotate [first point..COM] line to be along +x (for rotation invariant turtles), scales the arc length to be targetLength (for scale invariant turtles).
Rotate the start point of the turtle.

Geometry and Topology

Finds the center of mass of the uniform density wire specified by turtleList
Slides the origin of a closed turtle so that the first point of the turtle is at least as far from the center of mass as any other point on the turtle.

Making Turtles for Gargoyle Slices (implements GetShapeOfSlice)
First, we make a turtleTail out of the vector from the bottom left to bottom right points.  We know that these are the first and ninth text points.
Next, we package it away and send it off

Making Turtles for Gargoyle Segments (implements SegmentToTurtle)


Modifying Turtles
Ever try flipping a turtle?  They can't get back on their feet!  Flips a turtle and normalizes it.
Flips a turtle without normalizing it

Comparing Turtles to Turtles
Try to quickly find an answer for all turtle1-turtle2 matches
No quick reject
 [Artwork node; type 'Artwork on' to command tool] 
turtle1 is the from turtle and turtle2 is the scene turtle in all cases as of September 5, 1987.
Identify quick reject cases.
Set up a generator.
One turtle to use now and another turtle to use when the start position changes.
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