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
53 lines
1.3 KiB
C++
53 lines
1.3 KiB
C++
#include "QuadraticUtilities.h"
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#include <math.h>
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int quadraticRoots(double A, double B, double C, double t[2]) {
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B *= 2;
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double square = B * B - 4 * A * C;
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if (square < 0) {
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return 0;
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}
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double squareRt = sqrt(square);
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double Q = (B + (B < 0 ? -squareRt : squareRt)) / -2;
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double ratio;
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int foundRoots = 0;
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if ((Q <= A) ^ (Q < 0)) {
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ratio = Q / A;
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if (!isnan(ratio)) {
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t[foundRoots++] = ratio;
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}
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}
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if ((C <= Q) ^ (C < 0)) {
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ratio = C / Q;
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if (!isnan(ratio)) {
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t[foundRoots++] = ratio;
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}
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}
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return foundRoots;
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}
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void dxdy_at_t(const Quadratic& quad, double t, double& x, double& y) {
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double a = t - 1;
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double b = 1 - 2 * t;
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double c = t;
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if (&x) {
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x = a * quad[0].x + b * quad[1].x + c * quad[2].x;
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}
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if (&y) {
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y = a * quad[0].y + b * quad[1].y + c * quad[2].y;
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}
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}
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void xy_at_t(const Quadratic& quad, double t, double& x, double& y) {
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double one_t = 1 - t;
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double a = one_t * one_t;
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double b = 2 * one_t * t;
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double c = t * t;
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if (&x) {
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x = a * quad[0].x + b * quad[1].x + c * quad[2].x;
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}
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if (&y) {
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y = a * quad[0].y + b * quad[1].y + c * quad[2].y;
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}
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}
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