81 lines
2.8 KiB
C++
81 lines
2.8 KiB
C++
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#include "CubicIntersection.h"
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#include "Intersections.h"
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#include "LineIntersection.h"
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static bool chop(const Cubic& smaller, const Cubic& larger,
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Intersections& intersections, double minT, double maxT);
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static bool intersect(const Cubic& smaller, const Cubic& larger,
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Intersections& intersections) {
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// FIXME: carry order with cubic so we don't call it repeatedly
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Cubic smallResult;
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if (reduceOrder(smaller, smallResult, kReduceOrder_NoQuadraticsAllowed) <= 2) {
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Cubic largeResult;
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if (reduceOrder(larger, largeResult, kReduceOrder_NoQuadraticsAllowed) <= 2) {
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_Point pt;
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const _Line& smallLine = (const _Line&) smallResult;
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const _Line& largeLine = (const _Line&) largeResult;
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if (!lineIntersect(smallLine, largeLine, &pt)) {
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return false;
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}
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double smallT = t_at(smallLine, pt);
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double largeT = t_at(largeLine, pt);
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intersections.add(smallT, largeT);
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return true;
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}
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}
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double minT, maxT;
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if (!bezier_clip(smaller, larger, minT, maxT)) {
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if (minT == maxT) {
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intersections.add(minT, 0.5);
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return true;
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}
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return false;
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}
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return chop(larger, smaller, intersections, minT, maxT);
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}
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bool chop(const Cubic& smaller, const Cubic& larger,
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Intersections& intersections, double minT, double maxT) {
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intersections.swap();
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if (maxT - minT > 0.8) { // http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf Multiple intersections
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CubicPair cubicPair;
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chop_at(larger, cubicPair, 0.5);
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int used = intersections.used();
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if (intersect(cubicPair.first(), smaller, intersections)) {
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intersections.offset(used, 0, 0.5);
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}
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used = intersections.used();
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if (intersect(cubicPair.second(), smaller, intersections)) {
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intersections.offset(used, 0.5, 1);
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}
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intersections.swap();
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return intersections.intersected();
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}
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Cubic cut;
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sub_divide(smaller, minT, maxT, cut);
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int used = intersections.used();
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bool result = intersect(cut, larger, intersections);
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if (result) {
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intersections.offset(used, minT, maxT);
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}
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intersections.swap();
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return result;
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}
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bool intersectStart(const Cubic& cubic1, const Cubic& cubic2,
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Intersections& intersections) {
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double minT1, minT2, maxT1, maxT2;
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if (!bezier_clip(cubic2, cubic1, minT1, maxT1)) {
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return false;
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}
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if (!bezier_clip(cubic1, cubic2, minT2, maxT2)) {
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return false;
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}
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if (maxT1 - minT1 < maxT2 - minT2) {
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intersections.swap();
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return chop(cubic1, cubic2, intersections, minT1, maxT1);
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}
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return chop(cubic2, cubic1, intersections, minT2, maxT2);
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}
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