8dcf114db9
M Intersection/DataTypes.cpp M Intersection/QuadraticIntersection_Test.cpp M Intersection/EdgeWalker.cpp M Intersection/LineQuadraticIntersection_Test.cpp M Intersection/LineIntersection_Test.cpp M Intersection/LineIntersection.cpp D Intersection/edge.xcodeproj M Intersection/SimplifyFindTop_Test.cpp M Intersection/DataTypes.h A Intersection/SimplifyRect4x4_Test.cpp M Intersection/CubicIntersection_Test.cpp M Intersection/QuadraticUtilities.h M Intersection/LineCubicIntersection_Test.cpp A Intersection/CurveUtilities.h M Intersection/QuadraticBezierClip.cpp M Intersection/QuadraticBounds.cpp M Intersection/LineUtilities.h M Intersection/Intersection_Tests.cpp M Intersection/Simplify.cpp M Intersection/EdgeWalker_TestUtility.cpp M Intersection/QuadraticUtilities.cpp M Intersection/thingsToDo.txt M Intersection/LineUtilities.cpp M Intersection/CubicUtilities.h M Intersection/SimplifyFindNext_Test.cpp M Intersection/Intersection_Tests.h M Intersection/CubicBezierClip.cpp M Intersection/ActiveEdge_Test.cpp M Intersection/CubicBounds.cpp M Intersection/Simplify.h M Intersection/SimplifyNew_Test.cpp M Intersection/EdgeWalker_Test.h M Intersection/CubicUtilities.cpp M Intersection/op.htm M Intersection/ConvexHull.cpp D Intersection/RectUtilities.cpp M Intersection/SimplifyAddIntersectingTs_Test.cpp git-svn-id: http://skia.googlecode.com/svn/trunk@4429 2bbb7eff-a529-9590-31e7-b0007b416f81
63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
#include "CurveIntersection.h"
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#include "CurveUtilities.h"
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#include "LineParameters.h"
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#include <algorithm> // used for std::swap
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// return false if unable to clip (e.g., unable to create implicit line)
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// caller should subdivide, or create degenerate if the values are too small
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bool bezier_clip(const Quadratic& q1, const Quadratic& q2, double& minT, double& maxT) {
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minT = 1;
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maxT = 0;
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// determine normalized implicit line equation for pt[0] to pt[3]
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// of the form ax + by + c = 0, where a*a + b*b == 1
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// find the implicit line equation parameters
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LineParameters endLine;
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endLine.quadEndPoints(q1);
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if (!endLine.normalize()) {
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printf("line cannot be normalized: need more code here\n");
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return false;
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}
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double distance = endLine.controlPtDistance(q1);
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// find fat line
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double top = 0;
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double bottom = distance / 2; // http://students.cs.byu.edu/~tom/557/text/cic.pdf (7.6)
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if (top > bottom) {
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std::swap(top, bottom);
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}
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// compute intersecting candidate distance
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Quadratic distance2y; // points with X of (0, 1/2, 1)
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endLine.quadDistanceY(q2, distance2y);
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int flags = 0;
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if (approximately_lesser(distance2y[0].y, top)) {
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flags |= kFindTopMin;
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} else if (approximately_greater(distance2y[0].y, bottom)) {
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flags |= kFindBottomMin;
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} else {
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minT = 0;
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}
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if (approximately_lesser(distance2y[2].y, top)) {
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flags |= kFindTopMax;
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} else if (approximately_greater(distance2y[2].y, bottom)) {
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flags |= kFindBottomMax;
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} else {
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maxT = 1;
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}
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// Find the intersection of distance convex hull and fat line.
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int idx = 0;
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do {
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int next = idx + 1;
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if (next == 3) {
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next = 0;
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}
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x_at(distance2y[idx], distance2y[next], top, bottom, flags, minT, maxT);
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idx = next;
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} while (idx);
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return minT < maxT; // returns false if distance shows no intersection
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}
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