a3f05facab
git-svn-id: http://skia.googlecode.com/svn/trunk@4118 2bbb7eff-a529-9590-31e7-b0007b416f81
64 lines
1.8 KiB
C++
64 lines
1.8 KiB
C++
#include "CurveIntersection.h"
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#include "Extrema.h"
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static int isBoundedByEndPoints(double a, double b, double c, double d)
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{
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return (a <= b && a <= c && b <= d && c <= d)
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|| (a >= b && a >= c && b >= d && c >= d);
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}
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double leftMostT(const Cubic& cubic, double startT, double endT) {
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double leftTs[2];
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_Point pt[2];
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int results = findExtrema(cubic[0].x, cubic[1].x, cubic[2].x, cubic[3].x,
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leftTs);
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int best = -1;
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for (int index = 0; index < results; ++index) {
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if (startT > leftTs[index] || leftTs[index] > endT) {
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continue;
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}
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if (best < 0) {
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best = index;
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continue;
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}
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xy_at_t(cubic, leftTs[0], pt[0].x, pt[0].y);
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xy_at_t(cubic, leftTs[1], pt[1].x, pt[1].y);
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if (pt[0].x > pt[1].x) {
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best = 1;
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}
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}
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if (best >= 0) {
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return leftTs[best];
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}
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xy_at_t(cubic, startT, pt[0].x, pt[0].y);
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xy_at_t(cubic, endT, pt[1].x, pt[1].y);
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return pt[0].x <= pt[1].x ? startT : endT;
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}
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void _Rect::setBounds(const Cubic& cubic) {
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set(cubic[0]);
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add(cubic[3]);
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double tValues[4];
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int roots = 0;
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if (!isBoundedByEndPoints(cubic[0].x, cubic[1].x, cubic[2].x, cubic[3].x)) {
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roots = findExtrema(cubic[0].x, cubic[1].x, cubic[2].x,
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cubic[3].x, tValues);
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}
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if (!isBoundedByEndPoints(cubic[0].y, cubic[1].y, cubic[2].y, cubic[3].y)) {
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roots += findExtrema(cubic[0].y, cubic[1].y, cubic[2].y,
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cubic[3].y, &tValues[roots]);
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}
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for (int x = 0; x < roots; ++x) {
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_Point result;
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xy_at_t(cubic, tValues[x], result.x, result.y);
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add(result);
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}
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}
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void _Rect::setRawBounds(const Cubic& cubic) {
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set(cubic[0]);
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for (int x = 1; x < 4; ++x) {
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add(cubic[x]);
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}
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}
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