shape ops work in progress
git-svn-id: http://skia.googlecode.com/svn/trunk@7738 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/Intersection/CubicConvexHull.cpp b/experimental/Intersection/CubicConvexHull.cpp
new file mode 100644
index 0000000..3be8c21
--- /dev/null
+++ b/experimental/Intersection/CubicConvexHull.cpp
@@ -0,0 +1,165 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "CubicUtilities.h"
+#include "CurveIntersection.h"
+#include "Intersections.h"
+#include "IntersectionUtilities.h"
+#include "LineIntersection.h"
+
+static const double tClipLimit = 0.8; // http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf see Multiple intersections
+
+class CubicIntersections : public Intersections {
+public:
+
+CubicIntersections(const Cubic& c1, const Cubic& c2, Intersections& i)
+ : cubic1(c1)
+ , cubic2(c2)
+ , intersections(i)
+ , depth(0)
+ , splits(0) {
+}
+
+bool intersect() {
+ double minT1, minT2, maxT1, maxT2;
+ if (!bezier_clip(cubic2, cubic1, minT1, maxT1)) {
+ return false;
+ }
+ if (!bezier_clip(cubic1, cubic2, minT2, maxT2)) {
+ return false;
+ }
+ int split;
+ if (maxT1 - minT1 < maxT2 - minT2) {
+ intersections.swap();
+ minT2 = 0;
+ maxT2 = 1;
+ split = maxT1 - minT1 > tClipLimit;
+ } else {
+ minT1 = 0;
+ maxT1 = 1;
+ split = (maxT2 - minT2 > tClipLimit) << 1;
+ }
+ return chop(minT1, maxT1, minT2, maxT2, split);
+}
+
+protected:
+
+bool intersect(double minT1, double maxT1, double minT2, double maxT2) {
+ Cubic smaller, larger;
+ // FIXME: carry last subdivide and reduceOrder result with cubic
+ sub_divide(cubic1, minT1, maxT1, intersections.swapped() ? larger : smaller);
+ sub_divide(cubic2, minT2, maxT2, intersections.swapped() ? smaller : larger);
+ Cubic smallResult;
+ if (reduceOrder(smaller, smallResult,
+ kReduceOrder_NoQuadraticsAllowed) <= 2) {
+ Cubic largeResult;
+ if (reduceOrder(larger, largeResult,
+ kReduceOrder_NoQuadraticsAllowed) <= 2) {
+ const _Line& smallLine = (const _Line&) smallResult;
+ const _Line& largeLine = (const _Line&) largeResult;
+ Intersections lineTs;
+ // FIXME: this doesn't detect or deal with coincident lines
+ if (!::intersect(smallLine, largeLine, lineTs)) {
+ return false;
+ }
+ if (intersections.swapped()) {
+ lineTs.fT[0][0] = interp(minT2, maxT2, lineTs.fT[0][0]);
+ lineTs.fT[1][0] = interp(minT1, maxT1, lineTs.fT[1][0]);
+ } else {
+ lineTs.fT[0][0] = interp(minT1, maxT1, lineTs.fT[0][0]);
+ lineTs.fT[1][0] = interp(minT2, maxT2, lineTs.fT[1][0]);
+ }
+ _Point pt;
+ xy_at_t(cubic1, lineTs.fT[0][0], pt.x, pt.y);
+ intersections.insert(lineTs.fT[0][0], lineTs.fT[1][0], pt);
+ return true;
+ }
+ }
+ double minT, maxT;
+ if (!bezier_clip(smaller, larger, minT, maxT)) {
+ if (minT == maxT) {
+ if (intersections.swapped()) {
+ minT1 = (minT1 + maxT1) / 2;
+ minT2 = interp(minT2, maxT2, minT);
+ } else {
+ minT1 = interp(minT1, maxT1, minT);
+ minT2 = (minT2 + maxT2) / 2;
+ }
+ _Point pt;
+ xy_at_t(cubic1, minT1, pt.x, pt.y);
+ intersections.insert(minT1, minT2, pt);
+ return true;
+ }
+ return false;
+ }
+
+ int split;
+ if (intersections.swapped()) {
+ double newMinT1 = interp(minT1, maxT1, minT);
+ double newMaxT1 = interp(minT1, maxT1, maxT);
+ split = (newMaxT1 - newMinT1 > (maxT1 - minT1) * tClipLimit) << 1;
+#define VERBOSE 0
+#if VERBOSE
+ printf("%s d=%d s=%d new1=(%g,%g) old1=(%g,%g) split=%d\n",
+ __FUNCTION__, depth, splits, newMinT1, newMaxT1, minT1, maxT1,
+ split);
+#endif
+ minT1 = newMinT1;
+ maxT1 = newMaxT1;
+ } else {
+ double newMinT2 = interp(minT2, maxT2, minT);
+ double newMaxT2 = interp(minT2, maxT2, maxT);
+ split = newMaxT2 - newMinT2 > (maxT2 - minT2) * tClipLimit;
+#if VERBOSE
+ printf("%s d=%d s=%d new2=(%g,%g) old2=(%g,%g) split=%d\n",
+ __FUNCTION__, depth, splits, newMinT2, newMaxT2, minT2, maxT2,
+ split);
+#endif
+ minT2 = newMinT2;
+ maxT2 = newMaxT2;
+ }
+ return chop(minT1, maxT1, minT2, maxT2, split);
+}
+
+bool chop(double minT1, double maxT1, double minT2, double maxT2, int split) {
+ ++depth;
+ intersections.swap();
+ if (split) {
+ ++splits;
+ if (split & 2) {
+ double middle1 = (maxT1 + minT1) / 2;
+ intersect(minT1, middle1, minT2, maxT2);
+ intersect(middle1, maxT1, minT2, maxT2);
+ } else {
+ double middle2 = (maxT2 + minT2) / 2;
+ intersect(minT1, maxT1, minT2, middle2);
+ intersect(minT1, maxT1, middle2, maxT2);
+ }
+ --splits;
+ intersections.swap();
+ --depth;
+ return intersections.intersected();
+ }
+ bool result = intersect(minT1, maxT1, minT2, maxT2);
+ intersections.swap();
+ --depth;
+ return result;
+}
+
+private:
+
+const Cubic& cubic1;
+const Cubic& cubic2;
+Intersections& intersections;
+int depth;
+int splits;
+};
+
+bool intersect(const Cubic& c1, const Cubic& c2, Intersections& i) {
+ CubicIntersections c(c1, c2, i);
+ return c.intersect();
+}