fail when coincidence is too far apart

src/pathops/SkOpSegment.cpp

 /*
  * 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 "SkIntersections.h"
 #include "SkOpContour.h"
 #include "SkOpSegment.h"
 #include "SkPathWriter.h"
@@ skipping 1275 matching lines @@
     while (oIndex > 0 && precisely_equal(other->fTs[oIndex - 1].fT, oStartT)) {
         --oIndex;
     }
     SkSTArray<kOutsideTrackedTCount, SkPoint, true> outsidePts;
     SkSTArray<kOutsideTrackedTCount, SkPoint, true> oOutsidePts;
     SkOpSpan* test = &fTs[index];
     const SkPoint* testPt = &test->fPt;
     double testT = test->fT;
     SkOpSpan* oTest = &other->fTs[oIndex];
     const SkPoint* oTestPt = &oTest->fPt;
-    SkASSERT(AlmostEqualUlps(*testPt, *oTestPt));
+    // paths with extreme data will fail this test and eject out of pathops altogether later on
+    // SkASSERT(AlmostEqualUlps(*testPt, *oTestPt));
     do {
         SkASSERT(test->fT < 1);
         SkASSERT(oTest->fT < 1);
 
         // consolidate the winding count even if done
         if ((test->fWindValue == 0 && test->fOppValue == 0)
                 || (oTest->fWindValue == 0 && oTest->fOppValue == 0)) {
             SkDEBUGCODE(int firstWind = test->fWindValue);
             SkDEBUGCODE(int firstOpp = test->fOppValue);
             do {
@@ skipping 162 matching lines @@
     int spanCount = fTs.count();
     if (spanCount <= 2) {
         return spanCount == 2;
     }
     int index = 1;
     const SkOpSpan* firstSpan = &fTs[index];
     int activePrior = checkSetAngle(0);
     const SkOpSpan* span = &fTs[0];
     if (firstSpan->fT == 0 || span->fTiny || span->fOtherT != 1 || span->fOther->multipleEnds()) {
         index = findStartSpan(0);  // curve start intersects
+        if (fTs[index].fT == 0) {
+            return false;
+        }
         SkASSERT(index > 0);
         if (activePrior >= 0) {
             addStartSpan(index);
         }
     }
     bool addEnd;
     int endIndex = spanCount - 1;
     span = &fTs[endIndex - 1];
     if ((addEnd = span->fT == 1 || span->fTiny)) {  // if curve end intersects
         endIndex = findEndSpan(endIndex);
@@ skipping 2903 matching lines @@
     SkASSERT(span->fWindValue > 0 || span->fOppValue != 0);
     span->fWindValue = 0;
     span->fOppValue = 0;
     if (span->fTiny || span->fSmall) {
         return;
     }
     SkASSERT(!span->fDone);
     span->fDone = true;
     ++fDoneSpans;
 }