1 files changed, 145 insertions, 0 deletions
diff --git a/experimental/Intersection/CubicIntersectionT.cpp b/experimental/Intersection/CubicIntersectionT.cpp
new file mode 100644
index 0000000000..d58bcb9002
--- /dev/null
+++ b/experimental/Intersection/CubicIntersectionT.cpp
@@ -0,0 +1,145 @@
+#include "CubicIntersection.h"
+#include "Intersections.h"
+#include "IntersectionUtilities.h"
+#include "LineIntersection.h"
+
+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) {
+            _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);
+            if (intersections.swapped()) {
+                smallT = interp(minT2, maxT2, smallT); 
+                largeT = interp(minT1, maxT1, largeT); 
+            } else {
+                smallT = interp(minT1, maxT1, smallT); 
+                largeT = interp(minT2, maxT2, largeT); 
+            }
+            intersections.add(smallT, largeT);
+            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;
+        printf("%s d=%d s=%d new1=(%g,%g) old1=(%g,%g) split=%d\n", __FUNCTION__, depth,
+            splits, newMinT1, newMaxT1, minT1, maxT1, split);
+        minT1 = newMinT1;
+        maxT1 = newMaxT1;
+    } else {
+        double newMinT2 = interp(minT2, maxT2, minT);
+        double newMaxT2 = interp(minT2, maxT2, maxT);
+        split = newMaxT2 - newMinT2 > (maxT2 - minT2) * tClipLimit;
+        printf("%s d=%d s=%d new2=(%g,%g) old2=(%g,%g) split=%d\n", __FUNCTION__, depth,
+            splits, newMinT2, newMaxT2, minT2, maxT2, split);
+        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 intersectStartT(const Cubic& c1, const Cubic& c2, Intersections& i) {
+    CubicIntersections c(c1, c2, i);
+    return c.intersect();
+}
+