Add some new PolyUtils tests.

Also:
* clean up PolyUtils checks to be correct and consistent.
* fix some bugs discovered by the unit tests.

Bug: skia:
Change-Id: I1a8e07d13cb44fecc67344154dc1002f3f910f5d
Reviewed-on: https://skia-review.googlesource.com/138592
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

3 files changed, 274 insertions, 80 deletions

diff --git a/tests/InsetConvexPolyTest.cpp b/tests/InsetConvexPolyTest.cpp
index 022060c0f4..facabb76fa 100644
--- a/tests/InsetConvexPolyTest.cpp
+++ b/tests/InsetConvexPolyTest.cpp
@@ -7,30 +7,6 @@
 #include "Test.h"
 #include "SkPolyUtils.h"
 
-static bool is_convex(const SkTDArray<SkPoint>& poly) {
-    if (poly.count() < 3) {
-        return false;
-    }
-
-    SkVector v0 = poly[0] - poly[poly.count() - 1];
-    SkVector v1 = poly[1] - poly[poly.count() - 1];
-    SkScalar winding = v0.cross(v1);
-
-    for (int i = 0; i < poly.count()-1; ++i) {
-        int j = i + 1;
-        int k = (i + 2) % poly.count();
-
-        SkVector v0 = poly[j] - poly[i];
-        SkVector v1 = poly[k] - poly[i];
-        SkScalar perpDot = v0.cross(v1);
-        if (winding*perpDot < 0) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
 DEF_TEST(InsetConvexPoly, reporter) {
     SkTDArray<SkPoint> rrectPoly;
 
@@ -55,18 +31,18 @@ DEF_TEST(InsetConvexPoly, reporter) {
     *rrectPoly.push() = SkPoint::Make(-100 - 4.330127f, 50 + 2.5f);
     *rrectPoly.push() = SkPoint::Make(-100 - 3.535534f, 50 + 3.535534f);
     *rrectPoly.push() = SkPoint::Make(-100 - 2.5f, 50 + 4.330127f);
-    REPORTER_ASSERT(reporter, is_convex(rrectPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(rrectPoly.begin(), rrectPoly.count()));
 
     // inset a little
     SkTDArray<SkPoint> insetPoly;
-    bool result = SkInsetConvexPolygon(&rrectPoly[0], rrectPoly.count(), 3, &insetPoly);
+    bool result = SkInsetConvexPolygon(rrectPoly.begin(), rrectPoly.count(), 3, &insetPoly);
     REPORTER_ASSERT(reporter, result);
-    REPORTER_ASSERT(reporter, is_convex(insetPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(insetPoly.begin(), insetPoly.count()));
 
     // inset to rect
-    result = SkInsetConvexPolygon(&rrectPoly[0], rrectPoly.count(), 10, &insetPoly);
+    result = SkInsetConvexPolygon(rrectPoly.begin(), rrectPoly.count(), 10, &insetPoly);
     REPORTER_ASSERT(reporter, result);
-    REPORTER_ASSERT(reporter, is_convex(insetPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(insetPoly.begin(), insetPoly.count()));
     REPORTER_ASSERT(reporter, insetPoly.count() == 4);
     if (insetPoly.count() == 4) {
         REPORTER_ASSERT(reporter, insetPoly[0].equals(-95, 45));
@@ -77,9 +53,9 @@ DEF_TEST(InsetConvexPoly, reporter) {
 
     // just to full inset
     // fails, but outputs a line segment
-    result = SkInsetConvexPolygon(&rrectPoly[0], rrectPoly.count(), 55, &insetPoly);
+    result = SkInsetConvexPolygon(rrectPoly.begin(), rrectPoly.count(), 55, &insetPoly);
     REPORTER_ASSERT(reporter, !result);
-    REPORTER_ASSERT(reporter, !is_convex(insetPoly));
+    REPORTER_ASSERT(reporter, !SkIsConvexPolygon(insetPoly.begin(), insetPoly.count()));
     REPORTER_ASSERT(reporter, insetPoly.count() == 2);
     if (insetPoly.count() == 2) {
         REPORTER_ASSERT(reporter, insetPoly[0].equals(-50, 0));
@@ -87,7 +63,7 @@ DEF_TEST(InsetConvexPoly, reporter) {
     }
 
     // past full inset
-    result = SkInsetConvexPolygon(&rrectPoly[0], rrectPoly.count(), 75, &insetPoly);
+    result = SkInsetConvexPolygon(rrectPoly.begin(), rrectPoly.count(), 75, &insetPoly);
     REPORTER_ASSERT(reporter, !result);
     REPORTER_ASSERT(reporter, insetPoly.count() == 0);
 
@@ -120,10 +96,11 @@ DEF_TEST(InsetConvexPoly, reporter) {
     *clippedRRectPoly.push() = SkPoint::Make(381.195313f, 432.207275f);
     *clippedRRectPoly.push() = SkPoint::Make(377.312134f, 432.947998f);
     *clippedRRectPoly.push() = SkPoint::Make(342.289948f, 432.947998f);
-    REPORTER_ASSERT(reporter, is_convex(clippedRRectPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(clippedRRectPoly.begin(),
+                                                clippedRRectPoly.count()));
 
-    result = SkInsetConvexPolygon(&clippedRRectPoly[0], clippedRRectPoly.count(), 32.3699417f,
+    result = SkInsetConvexPolygon(clippedRRectPoly.begin(), clippedRRectPoly.count(), 32.3699417f,
                                   &insetPoly);
     REPORTER_ASSERT(reporter, result);
-    REPORTER_ASSERT(reporter, is_convex(insetPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(insetPoly.begin(), insetPoly.count()));
 }
diff --git a/tests/OffsetSimplePolyTest.cpp b/tests/OffsetSimplePolyTest.cpp
index 547dc9e529..0f4f18f2ad 100644
--- a/tests/OffsetSimplePolyTest.cpp
+++ b/tests/OffsetSimplePolyTest.cpp
@@ -7,30 +7,6 @@
 #include "Test.h"
 #include "SkPolyUtils.h"
 
-static bool is_convex(const SkTDArray<SkPoint>& poly) {
-    if (poly.count() < 3) {
-        return false;
-    }
-
-    SkVector v0 = poly[0] - poly[poly.count() - 1];
-    SkVector v1 = poly[1] - poly[poly.count() - 1];
-    SkScalar winding = v0.cross(v1);
-
-    for (int i = 0; i < poly.count()-1; ++i) {
-        int j = i + 1;
-        int k = (i + 2) % poly.count();
-
-        SkVector v0 = poly[j] - poly[i];
-        SkVector v1 = poly[k] - poly[i];
-        SkScalar perpDot = v0.cross(v1);
-        if (winding*perpDot < 0) {
-            return false;
-        }
-    }
-
-    return true;
-}
-
 DEF_TEST(OffsetSimplePoly, reporter) {
     SkTDArray<SkPoint> rrectPoly;
 
@@ -58,18 +34,18 @@ DEF_TEST(OffsetSimplePoly, reporter) {
     *rrectPoly.push() = SkPoint::Make(-100 - 4.330127f, 50 + 2.5f);
     *rrectPoly.push() = SkPoint::Make(-100 - 3.535534f, 50 + 3.535534f);
     *rrectPoly.push() = SkPoint::Make(-100 - 2.5f, 50 + 4.330127f);
-    REPORTER_ASSERT(reporter, is_convex(rrectPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(rrectPoly.begin(), rrectPoly.count()));
 
     // inset a little
     SkTDArray<SkPoint> offsetPoly;
-    bool result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 3, &offsetPoly);
+    bool result = SkOffsetSimplePolygon(rrectPoly.begin(), rrectPoly.count(), 3, &offsetPoly);
     REPORTER_ASSERT(reporter, result);
-    REPORTER_ASSERT(reporter, is_convex(offsetPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(offsetPoly.begin(), offsetPoly.count()));
 
     // inset to rect
-    result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 10, &offsetPoly);
+    result = SkOffsetSimplePolygon(rrectPoly.begin(), rrectPoly.count(), 10, &offsetPoly);
     REPORTER_ASSERT(reporter, result);
-    REPORTER_ASSERT(reporter, is_convex(offsetPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(offsetPoly.begin(), offsetPoly.count()));
     REPORTER_ASSERT(reporter, offsetPoly.count() == 4);
     if (offsetPoly.count() == 4) {
         REPORTER_ASSERT(reporter, offsetPoly[0].equals(-95, 45));
@@ -80,9 +56,9 @@ DEF_TEST(OffsetSimplePoly, reporter) {
 
     // just to full inset
     // fails, but outputs a line segment
-    result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 55, &offsetPoly);
+    result = SkOffsetSimplePolygon(rrectPoly.begin(), rrectPoly.count(), 55, &offsetPoly);
     REPORTER_ASSERT(reporter, !result);
-    REPORTER_ASSERT(reporter, !is_convex(offsetPoly));
+    REPORTER_ASSERT(reporter, !SkIsConvexPolygon(offsetPoly.begin(), offsetPoly.count()));
     REPORTER_ASSERT(reporter, offsetPoly.count() == 2);
     if (offsetPoly.count() == 2) {
         REPORTER_ASSERT(reporter, offsetPoly[0].equals(-50, 0));
@@ -90,7 +66,7 @@ DEF_TEST(OffsetSimplePoly, reporter) {
     }
 
     // past full inset
-    result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 75, &offsetPoly);
+    result = SkOffsetSimplePolygon(rrectPoly.begin(), rrectPoly.count(), 75, &offsetPoly);
     REPORTER_ASSERT(reporter, !result);
 
     // troublesome case
@@ -122,12 +98,13 @@ DEF_TEST(OffsetSimplePoly, reporter) {
     *clippedRRectPoly.push() = SkPoint::Make(381.195313f, 432.207275f);
     *clippedRRectPoly.push() = SkPoint::Make(377.312134f, 432.947998f);
     *clippedRRectPoly.push() = SkPoint::Make(342.289948f, 432.947998f);
-    REPORTER_ASSERT(reporter, is_convex(clippedRRectPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(clippedRRectPoly.begin(),
+                                                clippedRRectPoly.count()));
 
-    result = SkOffsetSimplePolygon(&clippedRRectPoly[0], clippedRRectPoly.count(), 32.3699417f,
+    result = SkOffsetSimplePolygon(clippedRRectPoly.begin(), clippedRRectPoly.count(), 32.3699417f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
-    REPORTER_ASSERT(reporter, is_convex(offsetPoly));
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(offsetPoly.begin(), offsetPoly.count()));
 
     ////////////////////////////////////////////////////////////////////////////////
     // Concave tests
@@ -145,46 +122,54 @@ DEF_TEST(OffsetSimplePoly, reporter) {
     *starPoly.push() = SkPoint::Make(-28.86f, 0.0f);
     *starPoly.push() = SkPoint::Make(-43.30f, -25.0f);
     *starPoly.push() = SkPoint::Make(-14.43f, -25.0f);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(starPoly.begin(), starPoly.count()));
 
     // try a variety of distances
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 0.1f,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), 0.1f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 5.665f,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), 5.665f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 28,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), 28,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
     // down to a point
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 28.866f,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), 28.866f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, !result);
 
     // and past
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 50.5f,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), 50.5f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, !result);
 
     // and now out
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -0.1f,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), -0.1f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -5.6665f,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), -5.6665f,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -50,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), -50,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
-    result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -100,
+    result = SkOffsetSimplePolygon(starPoly.begin(), starPoly.count(), -100,
                                    &offsetPoly);
     REPORTER_ASSERT(reporter, result);
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(offsetPoly.begin(), offsetPoly.count()));
 
     SkTDArray<SkPoint> intersectingPoly;
     *intersectingPoly.push() = SkPoint::Make(0.0f, -50.0f);
@@ -201,6 +186,6 @@ DEF_TEST(OffsetSimplePoly, reporter) {
     *intersectingPoly.push() = SkPoint::Make(-14.43f, -25.0f);
 
     // SkOffsetSimplePolygon now assumes that the input is simple, so we'll just check for that
-    result = SkIsSimplePolygon(&intersectingPoly[0], intersectingPoly.count());
+    result = SkIsSimplePolygon(intersectingPoly.begin(), intersectingPoly.count());
     REPORTER_ASSERT(reporter, !result);
 }
diff --git a/tests/PolyUtilsTest.cpp b/tests/PolyUtilsTest.cpp
new file mode 100644
index 0000000000..bc5a1a4858
--- /dev/null
+++ b/tests/PolyUtilsTest.cpp
@@ -0,0 +1,232 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "Test.h"
+#include "SkPolyUtils.h"
+
+DEF_TEST(PolyUtils, reporter) {
+
+    SkTDArray<SkPoint> poly;
+    // init simple index map
+    uint16_t indexMap[256];
+    for (int i = 0; i < 256; ++i) {
+        indexMap[i] = i;
+    }
+    SkTDArray<uint16_t> triangleIndices;
+
+    // skinny triangle
+    *poly.push() = SkPoint::Make(-100, 55);
+    *poly.push() = SkPoint::Make(100, 55);
+    *poly.push() = SkPoint::Make(102.5f, 54.330127f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) < 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // switch winding
+    poly[2].set(102.5f, 55.330127f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) > 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // make degenerate
+    poly[2].set(100 + 2.5f, 55);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) == 0);
+    // TODO: should these fail?
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, !SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                          &triangleIndices));
+
+    // giant triangle
+    poly[0].set(-1.0e+37f, 1.0e+37f);
+    poly[1].set(1.0e+37f, 1.0e+37f);
+    poly[2].set(-1.0e+37f, -1.0e+37f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) < 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // teeny triangle
+    poly[0].set(-1.0e-38f, 1.0e-38f);
+    poly[1].set(-1.0e-38f, -1.0e-38f);
+    poly[2].set(1.0e-38f, 1.0e-38f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) == 0);
+    // TODO: should these fail?
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, !SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                          &triangleIndices));
+
+    // triangle way off in space (relative to size so we don't completely obliterate values)
+    poly[0].set(-100 + 1.0e+9f, 55 - 1.0e+9f);
+    poly[1].set(100 + 1.0e+9f, 55 - 1.0e+9f);
+    poly[2].set(150 + 1.0e+9f, 100 - 1.0e+9f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) > 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    ///////////////////////////////////////////////////////////////////////
+    // round rect
+    poly.reset();
+    *poly.push() = SkPoint::Make(-100, 55);
+    *poly.push() = SkPoint::Make(100, 55);
+    *poly.push() = SkPoint::Make(100 + 2.5f, 50 + 4.330127f);
+    *poly.push() = SkPoint::Make(100 + 3.535534f, 50 + 3.535534f);
+    *poly.push() = SkPoint::Make(100 + 4.330127f, 50 + 2.5f);
+    *poly.push() = SkPoint::Make(105, 50);
+    *poly.push() = SkPoint::Make(105, -50);
+    *poly.push() = SkPoint::Make(100 + 4.330127f, -50 - 2.5f);
+    *poly.push() = SkPoint::Make(100 + 3.535534f, -50 - 3.535534f);
+    *poly.push() = SkPoint::Make(100 + 2.5f, -50 - 4.330127f);
+    *poly.push() = SkPoint::Make(100, -55);
+    *poly.push() = SkPoint::Make(-100, -55);
+    *poly.push() = SkPoint::Make(-100 - 2.5f, -50 - 4.330127f);
+    *poly.push() = SkPoint::Make(-100 - 3.535534f, -50 - 3.535534f);
+    *poly.push() = SkPoint::Make(-100 - 4.330127f, -50 - 2.5f);
+    *poly.push() = SkPoint::Make(-105, -50);
+    *poly.push() = SkPoint::Make(-105, 50);
+    *poly.push() = SkPoint::Make(-100 - 4.330127f, 50 + 2.5f);
+    *poly.push() = SkPoint::Make(-100 - 3.535534f, 50 + 3.535534f);
+    *poly.push() = SkPoint::Make(-100 - 2.5f, 50 + 4.330127f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) < 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // translate far enough to obliterate some low bits
+    for (int i = 0; i < poly.count(); ++i) {
+        poly[i].offset(1.0e+7f, 1.0e+7f);
+    }
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) < 0);
+    // Due to floating point error it's no longer convex
+    REPORTER_ASSERT(reporter, !SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                          &triangleIndices));
+
+    // translate a little farther to create some coincident vertices
+    for (int i = 0; i < poly.count(); ++i) {
+        poly[i].offset(4.0e+7f, 4.0e+7f);
+    }
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) < 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    // These can't handle coincident vertices
+    REPORTER_ASSERT(reporter, !SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, !SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                          &triangleIndices));
+
+    // troublesome case -- clipped roundrect
+    poly.reset();
+    *poly.push() = SkPoint::Make(335.928101f, 428.219055f);
+    *poly.push() = SkPoint::Make(330.414459f, 423.034912f);
+    *poly.push() = SkPoint::Make(325.749084f, 417.395508f);
+    *poly.push() = SkPoint::Make(321.931946f, 411.300842f);
+    *poly.push() = SkPoint::Make(318.963074f, 404.750977f);
+    *poly.push() = SkPoint::Make(316.842468f, 397.745850f);
+    *poly.push() = SkPoint::Make(315.570068f, 390.285522f);
+    *poly.push() = SkPoint::Make(315.145966f, 382.369965f);
+    *poly.push() = SkPoint::Make(315.570068f, 374.454346f);
+    *poly.push() = SkPoint::Make(316.842468f, 366.994019f);
+    *poly.push() = SkPoint::Make(318.963074f, 359.988892f);
+    *poly.push() = SkPoint::Make(321.931946f, 353.439056f);
+    *poly.push() = SkPoint::Make(325.749084f, 347.344421f);
+    *poly.push() = SkPoint::Make(330.414459f, 341.705017f);
+    *poly.push() = SkPoint::Make(335.928101f, 336.520813f);
+    *poly.push() = SkPoint::Make(342.289948f, 331.791901f);
+    *poly.push() = SkPoint::Make(377.312134f, 331.791901f);
+    *poly.push() = SkPoint::Make(381.195313f, 332.532593f);
+    *poly.push() = SkPoint::Make(384.464935f, 334.754700f);
+    *poly.push() = SkPoint::Make(386.687042f, 338.024292f);
+    *poly.push() = SkPoint::Make(387.427765f, 341.907532f);
+    *poly.push() = SkPoint::Make(387.427765f, 422.832367f);
+    *poly.push() = SkPoint::Make(386.687042f, 426.715576f);
+    *poly.push() = SkPoint::Make(384.464935f, 429.985168f);
+    *poly.push() = SkPoint::Make(381.195313f, 432.207275f);
+    *poly.push() = SkPoint::Make(377.312134f, 432.947998f);
+    *poly.push() = SkPoint::Make(342.289948f, 432.947998f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) > 0);
+    REPORTER_ASSERT(reporter, SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // a star is born
+    poly.reset();
+    *poly.push() = SkPoint::Make(0.0f, -50.0f);
+    *poly.push() = SkPoint::Make(14.43f, -25.0f);
+    *poly.push() = SkPoint::Make(43.30f, -25.0f);
+    *poly.push() = SkPoint::Make(28.86f, 0.0f);
+    *poly.push() = SkPoint::Make(43.30f, 25.0f);
+    *poly.push() = SkPoint::Make(14.43f, 25.0f);
+    *poly.push() = SkPoint::Make(0.0f, 50.0f);
+    *poly.push() = SkPoint::Make(-14.43f, 25.0f);
+    *poly.push() = SkPoint::Make(-43.30f, 25.0f);
+    *poly.push() = SkPoint::Make(-28.86f, 0.0f);
+    *poly.push() = SkPoint::Make(-43.30f, -25.0f);
+    *poly.push() = SkPoint::Make(-14.43f, -25.0f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) > 0);
+    REPORTER_ASSERT(reporter, !SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // self-intersecting polygon
+    poly.reset();
+    *poly.push() = SkPoint::Make(0.0f, -50.0f);
+    *poly.push() = SkPoint::Make(14.43f, -25.0f);
+    *poly.push() = SkPoint::Make(43.30f, -25.0f);
+    *poly.push() = SkPoint::Make(-28.86f, 0.0f);
+    *poly.push() = SkPoint::Make(43.30f, 25.0f);
+    *poly.push() = SkPoint::Make(14.43f, 25.0f);
+    *poly.push() = SkPoint::Make(0.0f, 50.0f);
+    *poly.push() = SkPoint::Make(-14.43f, 25.0f);
+    *poly.push() = SkPoint::Make(-43.30f, 25.0f);
+    *poly.push() = SkPoint::Make(28.86f, 0.0f);
+    *poly.push() = SkPoint::Make(-43.30f, -25.0f);
+    *poly.push() = SkPoint::Make(-14.43f, -25.0f);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) > 0);
+    REPORTER_ASSERT(reporter, !SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, !SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    // running this just to make sure it doesn't crash
+    // the fact that it succeeds doesn't mean anything since the input is not simple
+    REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                         &triangleIndices));
+
+    // self-intersecting polygon with coincident point
+    poly.reset();
+    *poly.push() = SkPoint::Make(0.0f, 0.0f);
+    *poly.push() = SkPoint::Make(-50, -50);
+    *poly.push() = SkPoint::Make(50, -50);
+    *poly.push() = SkPoint::Make(0.00000001f, -0.00000001f);
+    *poly.push() = SkPoint::Make(-50, 50);
+    *poly.push() = SkPoint::Make(50, 50);
+    REPORTER_ASSERT(reporter, SkGetPolygonWinding(poly.begin(), poly.count()) == 0);
+    REPORTER_ASSERT(reporter, !SkIsConvexPolygon(poly.begin(), poly.count()));
+    REPORTER_ASSERT(reporter, !SkIsSimplePolygon(poly.begin(), poly.count()));
+    triangleIndices.reset();
+    // running this just to make sure it doesn't crash
+    REPORTER_ASSERT(reporter, !SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
+                                                          &triangleIndices));
+}