path ops -- rewrite angle sort

tests/PathOpsAngleTest.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkOpSegment.h"
+#include "SkTArray.h"
 #include "Test.h"
 
 static const SkPoint cubics[][4] = {
 /* 0 */    {{0, 1}, {2, 6}, {4, 2}, {5, 3}},
 /* 1 */    {{10, 234}, {10, 229.581726f}, {13.5817204f, 226}, {18, 226}},
 /* 2 */    {{132, 11419}, {130.89543151855469f, 11419}, {130, 11418.1044921875f}, {130, 11417}},
 /* 3 */    {{130.04275512695312f, 11417.4130859375f}, {130.23307800292969f, 11418.3193359375f},
                     {131.03709411621094f, 11419}, {132, 11419}},
 /* 4 */    {{0,1}, {0,5}, {4,1}, {6,4}},
 /* 5 */    {{1,5}, {4,6}, {1,0}, {4,0}},
 /* 6 */    {{0,1}, {0,4}, {5,1}, {6,4}},
 /* 7 */    {{0,1}, {1,2}, {1,0}, {6,1}},
 /* 8 */    {{0,3}, {0,1}, {2,0}, {1,0}},
 /* 9 */    {{189,7}, {189,5.3431458473205566f}, {190.3431396484375f,4}, {192,4}},
 /* 10 */   {{0,1}, {1,3}, {1,0}, {6,4}},
 /* 11 */   {{0,1}, {2,3}, {2,1}, {4,3}},
 /* 12 */   {{1,2}, {3,4}, {1,0}, {3,2}},
+/* 13 */   {{0,1}, {4,6}, {4,3}, {5,4}},
+/* 14 */   {{806,11419}, {806.962890625,11419}, {807.76690673828125,11418.3193359375}, {807.957275390625,11417.4130859375}},
+/* 15 */   {{808,11417}, {808,11418.1044921875}, {807.10455322265625,11419}, {806,11419}},
+/* 16 */   {{132,11419}, {130.89543151855469,11419}, {130,11418.1044921875}, {130,11417}},
+/* 17 */   {{130.04275512695312,11417.4130859375}, {130.23312377929687,11418.3193359375}, {131.03707885742187,11419}, {132,11419}},
 };
 
 static const SkPoint quads[][3] = {
 /* 0 */    {{12.3423996f, 228.342407f}, {10, 230.686295f}, {10, 234}},
 /* 1 */    {{304.24319458007812f,591.75677490234375f}, {306,593.51470947265625f}, {306,596}},
+/* 2 */    {{0,0}, {3,1}, {0,3}},
+/* 3 */    {{0,1}, {3,1}, {0,2}},
 };
 
 static const SkPoint lines[][2] = {
 /* 0 */    {{6, 2}, {2, 4}},
 /* 1 */    {{306,617}, {306,590}},
 /* 2 */    {{306,596}, {306,617}},
 /* 3 */    {{6,4}, {0,1}},
 /* 4 */    {{6,1}, {0,1}},
 /* 5 */    {{1,0}, {0,3}},
 /* 6 */    {{246,4}, {189,4}},
 /* 7 */    {{192,4}, {243,4}},
 /* 8 */    {{4,3}, {0,1}},
 /* 9 */    {{3,2}, {1,2}},
+/* 10 */   {{6,4}, {3,4}},
 };
 
 struct SortSet {
     const SkPoint* ptData;
     int ptCount;
     double tStart;
     double tEnd;
+    SkPoint endPt;
 };
 
 static const SortSet set1[] = {
-    {cubics[0], 4, 0.66666987081928919, 0.875},
-    {lines[0], 2, 0.574070336, 0.388888889},
-    {cubics[0], 4, 0.66666987081928919, 0.4050371120499307 },
-    {lines[0], 2, 0.574070336, 0.9140625},
+    {cubics[0], 4, 0.66666987081928919, 0.875, {0, 0}},
+    {lines[0], 2, 0.574070336, 0.388888889, {0, 0}},
+    {cubics[0], 4, 0.66666987081928919, 0.4050371120499307, {0, 0}},
+    {lines[0], 2, 0.574070336, 0.9140625, {0, 0}},
+};
+
+static const SortSet set1a[] = {
+    {cubics[0], 4, 0.666666667, 0.405037112, {4.58007812f,2.83203125f}},
+    {lines[0], 2, 0.574074074, 0.9140625, {4.44444466f,2.77777767f}},
 };
 
 static const SortSet set2[] = {
-    {cubics[0], 4, 0.666666667, 0.875},
-    {lines[0], 2, 0.574074074, 0.388888889},
-    {cubics[0], 4, 0.666666667, 0.405037112},
-    {lines[0], 2, 0.574074074, 0.9140625},
+    {cubics[0], 4, 0.666666667, 0.875, {0, 0}},
+    {lines[0], 2, 0.574074074, 0.388888889, {0, 0}},
+    {cubics[0], 4, 0.666666667, 0.405037112, {0, 0}},
+    {lines[0], 2, 0.574074074, 0.9140625, {0, 0}},
 };
 
 static const SortSet set3[] = {
-    {cubics[1], 4, 0, 1},
-    {quads[0], 3, 1, 0},
+    {cubics[1], 4, 0, 1, {0, 0}},
+    {quads[0], 3, 1, 0, {0, 0}},
 };
 
 static const SortSet set4[] = {
-    {cubics[2], 4, 0.812114222, 1},
-    {cubics[3], 4, 0.0684734759, 0},
+    {cubics[2], 4, 0.812114222, 1, {0, 0}},
+    {cubics[3], 4, 0.0684734759, 0, {0, 0}},
 };
 
 static const SortSet set5[] = {
-    {lines[1], 2, 0.777777778, 1},
-    {quads[1], 3, 1, 4.34137342e-06},
-    {lines[2], 2, 0, 1},
+    {lines[1], 2, 0.777777778, 1, {0, 0}},
+    {quads[1], 3, 1, 4.34137342e-06, {0, 0}},
+    {lines[2], 2, 0, 1, {0, 0}},
+};
+
+static const SortSet set5a[] = {
+    {lines[1], 2, 0.777777778, 1, {306,590}},
+    {quads[1], 3, 1, 4.34137342e-06, {304.243195f,591.756775f}},
+    {lines[2], 2, 0, 1, {306,617}},
 };
 
 static const SortSet set6[] = {
-    {lines[3], 2, 0.407407407, 0.554627832},
-    {cubics[4], 4, 0.666666667, 0.548022446},
-    {lines[3], 2, 0.407407407, 0},
-    {cubics[4], 4, 0.666666667, 1},
+    {lines[3], 2, 0.407407407, 0.554627832, {0, 0}},
+    {cubics[4], 4, 0.666666667, 0.548022446, {0, 0}},
+    {lines[3], 2, 0.407407407, 0, {0, 0}},
+    {cubics[4], 4, 0.666666667, 1, {0, 0}},
+};
+
+static const SortSet set6a[] = {
+    {lines[3], 2, 0.407407407, 0.554627832, {2.6722331f,2.33611655f}},
+    {cubics[4], 4, 0.666666667, 0.548022446, {2.61642241f,2.83718514f}},
+    {lines[3], 2, 0.407407407, 0, {6,4}},
+    {cubics[4], 4, 0.666666667, 1, {6,4}},
 };
 
 static const SortSet set7[] = {
-    {cubics[5], 4, 0.545233342, 0.545454545},
-    {cubics[6], 4, 0.484938134, 0.484805744},
-    {cubics[5], 4, 0.545233342, 0},
-    {cubics[6], 4, 0.484938134, 0.545454545},
+    {cubics[5], 4, 0.545233342, 0.545454545, {0, 0}},
+    {cubics[6], 4, 0.484938134, 0.484805744, {0, 0}},
+    {cubics[5], 4, 0.545233342, 0, {0, 0}},
+    {cubics[6], 4, 0.484938134, 0.545454545, {0, 0}},
 };
 
 static const SortSet set8[] = {
-    {cubics[7], 4, 0.5, 0.522986744 },
-    {lines[4], 2, 0.75, 1},
-    {cubics[7], 4, 0.5, 0},
-    {lines[4], 2, 0.75, 0.737654321},
+    {cubics[7], 4, 0.5, 0.522986744, {0, 0}},
+    {lines[4], 2, 0.75, 1, {0, 0}},
+    {cubics[7], 4, 0.5, 0, {0, 0}},
+    {lines[4], 2, 0.75, 0.737654321, {0, 0}},
+};
+
+static const SortSet set8a[] = {
+    {cubics[7], 4, 0.5, 0.522986744, {1.60668361f,0.965592742f}},
+    {lines[4], 2, 0.75, 1, {0,1}},
+    {cubics[7], 4, 0.5, 0, {0,1}},
+    {lines[4], 2, 0.75, 0.737654321, {1.57407403f,1}},
 };
 
 static const SortSet set9[] = {
-    {cubics[8], 4, 0.4, 1},
-    {lines[5], 2, 0.36, 0},
-    {cubics[8], 4, 0.4, 0.394675838},
-    {lines[5], 2, 0.36, 0.363999782},
+    {cubics[8], 4, 0.4, 1, {0, 0}},
+    {lines[5], 2, 0.36, 0, {0, 0}},
+    {cubics[8], 4, 0.4, 0.394675838, {0, 0}},
+    {lines[5], 2, 0.36, 0.363999782, {0, 0}},
 };
 
 static const SortSet set10[] = {
-    {lines[6], 2, 0.947368421, 1},
-    {cubics[9], 4, 1, 0.500000357},
-    {lines[7], 2, 0, 1},
+    {lines[6], 2, 0.947368421, 1, {0, 0}},
+    {cubics[9], 4, 1, 0.500000357, {0, 0}},
+    {lines[7], 2, 0, 1, {0, 0}},
 };
 
 static const SortSet set11[] = {
-    {lines[3], 2, 0.75, 1},
-    {cubics[10], 4, 0.5, 0.228744269},
-    {lines[3], 2, 0.75, 0.627112191},
-    {cubics[10], 4, 0.5, 0.6339746},
+    {lines[3], 2, 0.75, 1, {0, 0}},
+    {cubics[10], 4, 0.5, 0.228744269, {0, 0}},
+    {lines[3], 2, 0.75, 0.627112191, {0, 0}},
+    {cubics[10], 4, 0.5, 0.6339746, {0, 0}},
 };
 
 static const SortSet set12[] = {
-    {cubics[12], 4, 0.5, 1},
-    {lines[8], 2, 0.5, 1},
-    {cubics[11], 4, 0.5, 0},
-    {lines[9], 2, 0.5, 1},
-    {cubics[12], 4, 0.5, 0},
-    {lines[8], 2, 0.5, 0},
-    {cubics[11], 4, 0.5, 1},
-    {lines[9], 2, 0.5, 0},
+    {cubics[12], 4, 0.5, 1, {0, 0}},
+    {lines[8], 2, 0.5, 1, {0, 0}},
+    {cubics[11], 4, 0.5, 0, {0, 0}},
+    {lines[9], 2, 0.5, 1, {0, 0}},
+    {cubics[12], 4, 0.5, 0, {0, 0}},
+    {lines[8], 2, 0.5, 0, {0, 0}},
+    {cubics[11], 4, 0.5, 1, {0, 0}},
+    {lines[9], 2, 0.5, 0, {0, 0}},
+};
+
+static const SortSet set13[] = {
+    {cubics[13], 4, 0.5, 0.400631046, {0, 0}},
+    {lines[10], 2, 0.791666667, 0.928, {0, 0}},
+    {lines[10], 2, 0.791666667, 0.333333333, {0, 0}},
+    {cubics[13], 4, 0.5, 0.866666667, {0, 0}},
+};
+
+static const SortSet set14[] = {
+    {quads[2], 3, 0.5, 0.310102051, {0, 0}},
+    {quads[3], 3, 0.5, 0.2, {0, 0}},
+    {quads[3], 3, 0.5, 0.770156212, {0, 0}},
+    {quads[2], 3, 0.5, 0.7, {0, 0}},
+};
+
+static const SortSet set15[] = {
+    {cubics[14], 4, 0.93081374, 1, {0, 0}},
+    {cubics[15], 4, 0.188518131, 0, {0, 0}},
+    {cubics[14], 4, 0.93081374, 0, {0, 0}},
+};
+
+static const SortSet set16[] = {
+    {cubics[17], 4, 0.0682619216, 0, {130.042755f,11417.4131f}},
+    {cubics[16], 4, 0.812302088, 1, {130,11417}},
+    {cubics[17], 4, 0.0682619216, 1, {132,11419}},
 };
 
 struct SortSetTests {
+    const char* name;
     const SortSet* set;
     size_t count;
-};
+    SkPoint startPt;
+};
+
+#define TEST_ENTRY(name) #name, name, SK_ARRAY_COUNT(name)
 
 static const SortSetTests tests[] = {
-    { set12, SK_ARRAY_COUNT(set12) },
-    { set11, SK_ARRAY_COUNT(set11) },
-    { set10, SK_ARRAY_COUNT(set10) },
-    { set9, SK_ARRAY_COUNT(set9) },
-    { set8, SK_ARRAY_COUNT(set8) },
-    { set7, SK_ARRAY_COUNT(set7) },
-    { set6, SK_ARRAY_COUNT(set6) },
-    { set2, SK_ARRAY_COUNT(set2) },
-    { set5, SK_ARRAY_COUNT(set5) },
-    { set4, SK_ARRAY_COUNT(set4) },
-    { set3, SK_ARRAY_COUNT(set3) },
-    { set1, SK_ARRAY_COUNT(set1) },
-};
-
-static void setup(const SortSet* set, const size_t idx, SkPoint const ** data,
-        SkOpSegment* seg, int* ts) {
+    { TEST_ENTRY(set16), {130.090179f,11417.5957f} },
+//    { TEST_ENTRY(set15), {0, 0}},
+    { TEST_ENTRY(set14), {0, 0}},
+    { TEST_ENTRY(set13), {0, 0}},
+    { TEST_ENTRY(set12), {0, 0}},
+    { TEST_ENTRY(set11), {0, 0}},
+    { TEST_ENTRY(set10), {0, 0}},
+    { TEST_ENTRY(set9), {0, 0}},
+    { TEST_ENTRY(set6a), {3.55555558f,2.77777767f} },
+    { TEST_ENTRY(set8a), {1.5f,1} },
+    { TEST_ENTRY(set8), {0, 0}},
+    { TEST_ENTRY(set7), {0, 0}},
+    { TEST_ENTRY(set6a), {3.55555558f,2.77777767f} },
+    { TEST_ENTRY(set6), {0, 0}},
+    { TEST_ENTRY(set5a), {306,596} },
+    { TEST_ENTRY(set5), {0, 0}},
+//    { TEST_ENTRY(set4), {0, 0}},
+    { TEST_ENTRY(set3), {0, 0}},
+    { TEST_ENTRY(set2), {0, 0}},
+//    { TEST_ENTRY(set1a), {3.70370364f,3.14814806f} },
+    { TEST_ENTRY(set1), {0, 0}},
+};
+
+#undef TEST_ENTRY
+
+static void setup(const SortSet* set, const size_t idx,
+        SkOpSegment* seg, int* ts, const SkPoint& startPt) {
     SkPoint start, end;
-    *data = set[idx].ptData;
+    const SkPoint* data = set[idx].ptData;
+    bool useIntersectPt = startPt.fX != 0 || startPt.fY != 0;
+    if (useIntersectPt) {
+        start = startPt;
+        end = set[idx].endPt;
+    }
     switch(set[idx].ptCount) {
         case 2: {
-            seg->addLine(*data, false, false);
+            seg->addLine(data, false, false);
             SkDLine dLine;
             dLine.set(set[idx].ptData);
+            if (useIntersectPt) {
+                break;
+            }
             start = dLine.xyAtT(set[idx].tStart).asSkPoint();
             end = dLine.xyAtT(set[idx].tEnd).asSkPoint();
             } break;
         case 3: {
-            seg->addQuad(*data, false, false);
+            seg->addQuad(data, false, false);
             SkDQuad dQuad;
             dQuad.set(set[idx].ptData);
+             if (useIntersectPt) {
+                break;
+            }
             start = dQuad.xyAtT(set[idx].tStart).asSkPoint();
             end = dQuad.xyAtT(set[idx].tEnd).asSkPoint();
             } break;
         case 4: {
-            seg->addCubic(*data, false, false);
+            seg->addCubic(data, false, false);
             SkDCubic dCubic;
             dCubic.set(set[idx].ptData);
+            if (useIntersectPt) {
+                break;
+            }
             start = dCubic.xyAtT(set[idx].tStart).asSkPoint();
             end = dCubic.xyAtT(set[idx].tEnd).asSkPoint();
             } break;
     }
     double tStart = set[idx].tStart;
     double tEnd = set[idx].tEnd;
     seg->addT(NULL, start, tStart);
     seg->addT(NULL, end, tEnd);
-    double tLeft = tStart < tEnd ? 0 : 1;
-    if (tStart != tLeft && tEnd != tLeft) {
-        seg->addT(NULL, set[idx].ptData[0], tLeft);
+    if (tStart != 0 && tEnd != 0) {
+        seg->addT(NULL, set[idx].ptData[0], 0);
     }
-    double tRight = tStart < tEnd ? 1 : 0;
-    if (tStart != tRight && tEnd != tRight) {
-        seg->addT(NULL, set[idx].ptData[set[idx].ptCount - 1], tRight);
+    if (tStart != 1 && tEnd != 1) {
+        seg->addT(NULL, set[idx].ptData[set[idx].ptCount - 1], 1);
     }
     int tIndex = 0;
     do {
         if (seg->t(tIndex) == set[idx].tStart) {
             ts[0] = tIndex;
         }
         if (seg->t(tIndex) == set[idx].tEnd) {
             ts[1] = tIndex;
         }
         if (seg->t(tIndex) >= 1) {
             break;
         }
     } while (++tIndex);
 }
 
 static void PathOpsAngleTest(skiatest::Reporter* reporter) {
     for (size_t index = 0; index < SK_ARRAY_COUNT(tests); ++index) {
         const SortSetTests& test = tests[index];
-        for (size_t idxL = 0; idxL < test.count - 1; ++idxL) {
-            SkOpSegment lesser, greater;
-            int lesserTs[2], greaterTs[2];
-            const SkPoint* lesserData, * greaterData;
+        SkTDArray<SkOpAngle> angles;
+        bool unsortable = false;
+        bool unorderable = false;
+        SkTArray<SkOpSegment> segs;
+        for (size_t idx = 0; idx < test.count; ++idx) {
+            int ts[2];
             const SortSet* set = test.set;
-            setup(set, idxL, &lesserData, &lesser, lesserTs);
-            size_t idxG = idxL + 1;
-            setup(set, idxG, &greaterData, &greater, greaterTs);
-            SkOpAngle first, second;
-            first.set(lesserData, SkPathOpsPointsToVerb(set[idxL].ptCount - 1), &lesser,
-                    lesserTs[0], lesserTs[1], lesser.spans());
-            second.set(greaterData, SkPathOpsPointsToVerb(set[idxG].ptCount - 1), &greater,
-                    greaterTs[0], greaterTs[1], greater.spans());
-            bool compare = first < second;
-            if (!compare) {
-                SkDebugf("%s test[%d]:  lesser[%d] > greater[%d]\n", __FUNCTION__,
-                        index, idxL,  idxG);
-                compare = first < second;
+            SkOpSegment& seg = segs.push_back();
+            setup(set, idx, &seg, ts, test.startPt);
+            SkOpAngle* angle = angles.append();
+            angle->set(&seg, ts[0], ts[1]);
+#if DEBUG_ANGLE
+            angle->setID(idx);
+#endif
+           if (angle->unsortable()) {
+#if DEBUG_ANGLE
+                SkDebugf("%s test[%s]:  angle[%d] unsortable\n", __FUNCTION__, test.name, idx);
+#endif
+                unsortable = true;
             }
-            REPORTER_ASSERT(reporter, compare);
+            if (angle->unorderable()) {
+#if DEBUG_ANGLE
+                SkDebugf("%s test[%s]:  angle[%d] unorderable\n", __FUNCTION__, test.name, idx);
+#endif
+                unorderable = true;
+            }
             reporter->bumpTestCount();
         }
+        if (unsortable || unorderable) {
+            continue;
+        }
+#if DEBUG_ANGLE
+        SkDebugf("%s test[%s]\n", __FUNCTION__, test.name);
+#endif
+        for (size_t idxL = 0; idxL < test.count; ++idxL) {
+            const SkOpAngle& first = angles[idxL];
+            for (size_t idxG = 0; idxG < test.count; ++idxG) {
+                if (idxL == idxG) {
+                    continue;
+                }
+                const SkOpAngle& second = angles[idxG];
+                bool compare = first < second;
+                if (idxL < idxG) {
+                    if (!compare) {
+                        SkDebugf("%s test[%s]:  first[%d] > second[%d]\n", __FUNCTION__,
+                                test.name,  idxL,  idxG);
+                        compare = first < second;
+                    }
+                    REPORTER_ASSERT(reporter, compare);
+                } else {
+                    SkASSERT(idxL > idxG);
+                    if (compare) {
+                        SkDebugf("%s test[%s]:  first[%d] < second[%d]\n", __FUNCTION__,
+                                test.name,  idxL,  idxG);
+                        compare = first < second;
+                    }
+                    REPORTER_ASSERT(reporter, !compare);
+                }
+                compare = second < first;
+                if (idxL < idxG) {
+                    if (compare) {
+                        SkDebugf("%s test[%s]:  second[%d] < first[%d]\n", __FUNCTION__,
+                                test.name,  idxL,  idxG);
+                        compare = second < first;
+                    }
+                    REPORTER_ASSERT(reporter, !compare);
+                } else {
+                    SkASSERT(idxL > idxG);
+                    if (!compare) {
+                        SkDebugf("%s test[%s]:  second[%d] > first[%d]\n", __FUNCTION__,
+                                test.name,  idxL,  idxG);
+                        compare = second < first;
+                    }
+                    REPORTER_ASSERT(reporter, compare);
+                }
+            }
+        }
+        reporter->bumpTestCount();
     }
 }
 
+#if 0
+static int find_slop(double x, double y, double rx, double ry) {
+    int slopBits = 0;
+    bool less1, less2;
+    double absX = fabs(x);
+    double absY = fabs(y);
+    double length = absX < absY ? absX / 2 + absY : absX + absY / 2;
+    int exponent;
+    (void) frexp(length, &exponent);
+    double epsilon = ldexp(FLT_EPSILON, exponent);
+    do {
+        // get the length as the larger plus half the smaller (both same signs)
+        // find the ulps of the length
+        // compute the offsets from there
+        double xSlop = epsilon * slopBits;
+        double ySlop = x * y < 0 ? -xSlop : xSlop; // OPTIMIZATION: use copysign / _copysign ?
+        double x1 = x - xSlop;
+        double y1 = y + ySlop;
+        double x_ry1 = x1 * ry;
+        double rx_y1 = rx * y1;
+        less1 = x_ry1 < rx_y1;
+        double x2 = x + xSlop;
+        double y2 = y - ySlop;
+        double x_ry2 = x2 * ry;
+        double rx_y2 = rx * y2;
+        less2 = x_ry2 < rx_y2;
+    } while (less1 == less2 && ++slopBits);
+    return slopBits;
+}
+
+// from http://stackoverflow.com/questions/1427422/cheap-algorithm-to-find-measure-of-angle-between-vectors
+static double diamond_angle(double y, double x)
+{
+    if (y >= 0)
+        return (x >= 0 ? y/(x+y) : 1-x/(-x+y)); 
+    else
+        return (x < 0 ? 2-y/(-x-y) : 3+x/(x-y)); 
+}
+
+static const double slopTests[][4] = {
+   // x                      y                       rx                      ry
+    {-0.058554756452593892, -0.18804585843827226, -0.018568569646021160, -0.059615294434479438},
+    {-0.0013717412948608398, 0.0041152238845825195, -0.00045837944195925573, 0.0013753175735478074},
+    {-2.1033774145221198, -1.4046019261273715e-008, -0.70062688352066704, -1.2706324683777995e-008},
+};
+
+static void PathOpsAngleFindSlop(skiatest::Reporter* reporter) {
+    for (size_t index = 0; index < SK_ARRAY_COUNT(slopTests); ++index) {
+        const double* slopTest = slopTests[index];
+        double x = slopTest[0];
+        double y = slopTest[1];
+        double rx = slopTest[2];
+        double ry = slopTest[3];
+        SkDebugf("%s  xy %d=%d\n", __FUNCTION__, (int) index, find_slop(x, y, rx, ry)); 
+        SkDebugf("%s rxy %d=%d\n", __FUNCTION__, (int) index, find_slop(rx, ry, x, y)); 
+        double angle = diamond_angle(y, x);
+        double rAngle = diamond_angle(ry, rx);
+        double diff = fabs(angle - rAngle);
+        SkDebugf("%s diamond xy=%1.9g rxy=%1.9g diff=%1.9g factor=%d\n", __FUNCTION__,
+                angle, rAngle, diff, (int) (diff / FLT_EPSILON));
+
+    }
+}
+#endif
+
 #include "TestClassDef.h"
 DEFINE_TESTCLASS_SHORT(PathOpsAngleTest)
+
+// DEFINE_TESTCLASS_SHORT(PathOpsAngleFindSlop)