save work in progress
git-svn-id: http://skia.googlecode.com/svn/trunk@3141 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/Intersection/CubicIntersection.cpp b/experimental/Intersection/CubicIntersection.cpp
index c41e0d7..13c4726 100644
--- a/experimental/Intersection/CubicIntersection.cpp
+++ b/experimental/Intersection/CubicIntersection.cpp
@@ -1,70 +1,20 @@
-#include "CubicIntersection.h"
+#include "CurveIntersection.h"
#include "Intersections.h"
+#include "IntersectionUtilities.h"
#include "LineIntersection.h"
-static bool chop(const Cubic& smaller, const Cubic& larger,
- Intersections& intersections, double minT, double maxT);
-
-static bool intersect(const Cubic& smaller, const Cubic& larger,
- Intersections& intersections) {
- // FIXME: carry order with cubic so we don't call it repeatedly
- Cubic smallResult;
- if (reduceOrder(smaller, smallResult, kReduceOrder_NoQuadraticsAllowed) <= 2) {
- Cubic largeResult;
- if (reduceOrder(larger, largeResult, kReduceOrder_NoQuadraticsAllowed) <= 2) {
- _Point pt;
- const _Line& smallLine = (const _Line&) smallResult;
- const _Line& largeLine = (const _Line&) largeResult;
- if (!lineIntersect(smallLine, largeLine, &pt)) {
- return false;
- }
- double smallT = t_at(smallLine, pt);
- double largeT = t_at(largeLine, pt);
- intersections.add(smallT, largeT);
- return true;
- }
- }
- double minT, maxT;
- if (!bezier_clip(smaller, larger, minT, maxT)) {
- if (minT == maxT) {
- intersections.add(minT, 0.5);
- return true;
- }
- return false;
- }
- return chop(larger, smaller, intersections, minT, maxT);
+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 chop(const Cubic& smaller, const Cubic& larger,
- Intersections& intersections, double minT, double maxT) {
- intersections.swap();
- if (maxT - minT > 0.8) { // http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf Multiple intersections
- CubicPair cubicPair;
- chop_at(larger, cubicPair, 0.5);
- int used = intersections.used();
- if (intersect(cubicPair.first(), smaller, intersections)) {
- intersections.offset(used, 0, 0.5);
- }
- used = intersections.used();
- if (intersect(cubicPair.second(), smaller, intersections)) {
- intersections.offset(used, 0.5, 1);
- }
- intersections.swap();
- return intersections.intersected();
- }
- Cubic cut;
- sub_divide(smaller, minT, maxT, cut);
- int used = intersections.used();
- bool result = intersect(cut, larger, intersections);
- if (result) {
- intersections.offset(used, minT, maxT);
- }
- intersections.swap();
- return result;
-}
-
-bool intersectStart(const Cubic& cubic1, const Cubic& cubic2,
- Intersections& intersections) {
+bool intersect() {
double minT1, minT2, maxT1, maxT2;
if (!bezier_clip(cubic2, cubic1, minT1, maxT1)) {
return false;
@@ -72,9 +22,133 @@
if (!bezier_clip(cubic1, cubic2, minT2, maxT2)) {
return false;
}
+ int split;
if (maxT1 - minT1 < maxT2 - minT2) {
intersections.swap();
- return chop(cubic1, cubic2, intersections, minT1, maxT1);
- }
- return chop(cubic2, cubic1, intersections, minT2, maxT2);
+ 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;
+ double smallT[2];
+ double largeT[2];
+ // FIXME: this doesn't detect or deal with coincident lines
+ if (!::intersect(smallLine, largeLine, smallT, largeT)) {
+ return false;
+ }
+ if (intersections.swapped()) {
+ smallT[0] = interp(minT2, maxT2, smallT[0]);
+ largeT[0] = interp(minT1, maxT1, largeT[0]);
+ } else {
+ smallT[0] = interp(minT1, maxT1, smallT[0]);
+ largeT[0] = interp(minT2, maxT2, largeT[0]);
+ }
+ intersections.add(smallT[0], largeT[0]);
+ 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;
+ }
+ intersections.add(minT1, minT2);
+ 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:
+
+static const double tClipLimit = 0.8; // http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf see Multiple intersections
+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();
+}
+