pathops work in progress

src/pathops/SkDQuadIntersection.cpp

 // Another approach is to start with the implicit form of one curve and solve
 // (seek implicit coefficients in QuadraticParameter.cpp
 // by substituting in the parametric form of the other.
 // The downside of this approach is that early rejects are difficult to come by.
 // http://planetmath.org/encyclopedia/GaloisTheoreticDerivationOfTheQuarticFormula.html#step
 
 
 #include "SkDQuadImplicit.h"
 #include "SkIntersections.h"
 #include "SkPathOpsLine.h"
@@ skipping 283 matching lines @@
     double tStep = ROUGH_EPSILON;
     SkDPoint t1[3], t2[3];
     int calcMask = ~0;
     do {
         if (calcMask & (1 << 1)) t1[1] = quad1.ptAtT(*t1Seed);
         if (calcMask & (1 << 4)) t2[1] = quad2.ptAtT(*t2Seed);
         if (t1[1].approximatelyEqual(t2[1])) {
             *pt = t1[1];
     #if ONE_OFF_DEBUG
             SkDebugf("%s t1=%1.9g t2=%1.9g (%1.9g,%1.9g) == (%1.9g,%1.9g)\n", __FUNCTION__,
-                    t1Seed, t2Seed, t1[1].fX, t1[1].fY, t1[2].fX, t1[2].fY);
+                    t1Seed, t2Seed, t1[1].fX, t1[1].fY, t2[1].fX, t2[1].fY);
     #endif
             return true;
         }
         if (calcMask & (1 << 0)) t1[0] = quad1.ptAtT(*t1Seed - tStep);
         if (calcMask & (1 << 2)) t1[2] = quad1.ptAtT(*t1Seed + tStep);
         if (calcMask & (1 << 3)) t2[0] = quad2.ptAtT(*t2Seed - tStep);
         if (calcMask & (1 << 5)) t2[2] = quad2.ptAtT(*t2Seed + tStep);
         double dist[3][3];
         // OPTIMIZE: using calcMask value permits skipping some distance calcuations
         //   if prior loop's results are moved to correct slot for reuse
@@ skipping 168 matching lines @@
     }
     double roots2[4];
     int rootCount2 = findRoots(i1, q2, roots2, useCubic, flip2, 0);
     double roots2Copy[4];
     int r2Count = addValidRoots(roots2, rootCount2, roots2Copy);
     SkDPoint pts2[4];
     for (index = 0; index < r2Count; ++index) {
         pts2[index] = q2.ptAtT(roots2Copy[index]);
     }
     if (r1Count == r2Count && r1Count <= 1) {
-        if (r1Count == 1) {
+        if (r1Count == 1 && used() == 0) {
             if (pts1[0].approximatelyEqual(pts2[0])) {
                 insert(roots1Copy[0], roots2Copy[0], pts1[0]);
             } else if (pts1[0].moreRoughlyEqual(pts2[0])) {
                 // experiment: try to find intersection by chasing t
-                rootCount = findRoots(i2, q1, roots1, useCubic, flip1, 0);
-                (void) addValidRoots(roots1, rootCount, roots1Copy);
-                rootCount2 = findRoots(i1, q2, roots2, useCubic, flip2, 0);
-                (void) addValidRoots(roots2, rootCount2, roots2Copy);
                 if (binary_search(q1, q2, roots1Copy, roots2Copy, pts1)) {
                     insert(roots1Copy[0], roots2Copy[0], pts1[0]);
                 }
             }
         }
         return fUsed;
     }
     int closest[4];
     double dist[4];
     bool foundSomething = false;
@@ skipping 45 matching lines @@
         }
         if (lowestIndex < 0) {
             break;
         }
         insert(roots1Copy[lowestIndex], roots2Copy[closest[lowestIndex]],
                 pts1[lowestIndex]);
         closest[lowestIndex] = -1;
     } while (++used < r1Count);
     return fUsed;
 }