path ops work in progress

src/pathops/SkAddIntersections.cpp

Index: src/pathops/SkAddIntersections.cpp
diff --git a/src/pathops/SkAddIntersections.cpp b/src/pathops/SkAddIntersections.cpp
index 05079845fed9dad737d03af79fdfdca6ba03bf22..5fa80ec50619f41a13f3592c9c7744207e5ef09d 100644
--- a/src/pathops/SkAddIntersections.cpp
+++ b/src/pathops/SkAddIntersections.cpp
@@ -363,15 +363,20 @@ bool AddIntersectTs(SkOpContour* test, SkOpContour* next) {
             if (pts == 2) {
                 if (wn.segmentType() <= SkIntersectionHelper::kLine_Segment
                         && wt.segmentType() <= SkIntersectionHelper::kLine_Segment) {
-                    wt.addCoincident(wn, ts, swap);
-                    continue;
-                }
-                if (wn.segmentType() >= SkIntersectionHelper::kQuad_Segment
+                    if (wt.addCoincident(wn, ts, swap)) {
+                        continue;
+                    }
+                    ts.cleanUpCoincidence();  // prefer (t == 0 or t == 1)
+                    pts = 1;
+                } else if (wn.segmentType() >= SkIntersectionHelper::kQuad_Segment
                         && wt.segmentType() >= SkIntersectionHelper::kQuad_Segment
                         && ts.isCoincident(0)) {
                     SkASSERT(ts.coincidentUsed() == 2);
-                    wt.addCoincident(wn, ts, swap);
-                    continue;
+                    if (wt.addCoincident(wn, ts, swap)) {
+                        continue;
+                    }
+                    ts.cleanUpCoincidence();  // prefer (t == 0 or t == 1)
+                    pts = 1;
                 }
             }
             if (pts >= 2) {
@@ -380,7 +385,11 @@ bool AddIntersectTs(SkOpContour* test, SkOpContour* next) {
                     const SkDPoint& next = ts.pt(pt + 1);
                     if (wt.isNear(ts[swap][pt], ts[swap][pt + 1], point, next)
                             && wn.isNear(ts[!swap][pt], ts[!swap][pt + 1], point, next)) {
-                        wt.addPartialCoincident(wn, ts, pt, swap);
+                        if (!wt.addPartialCoincident(wn, ts, pt, swap)) {
+                            // remove extra point if two map to same float values
+                            ts.cleanUpCoincidence();  // prefer (t == 0 or t == 1)
+                            pts = 1;
+                        }
                     }
                 }
             }