From 908cc8071cfe1ab9647b01cc1bf6eabc363676ab Mon Sep 17 00:00:00 2001
From: John Stiles <johnstiles@google.com>
Date: Mon, 27 Jun 2022 17:48:58 -0400
Subject: [PATCH] Revert "experimental alternative isconvex"

This reverts commit 64284e14827d8768e54582c0d8c81d0d33594f7c.

Reason for revert: unused code

Original change's description:
> experimental alternative isconvex
>
> Bug: skia:
> Change-Id: I55175a95d37aad9a656cd211fc6c7238bdb7d674
> Reviewed-on: https://skia-review.googlesource.com/c/173361
> Commit-Queue: Mike Reed <reed@google.com>
> Reviewed-by: Mike Reed <reed@google.com>

Change-Id: Ib00acfc0964ecfd2fe01689c0d46d0773d5c5258
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/553588
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
---
 src/utils/SkPolyUtils.cpp | 112 --------------------------------------
 src/utils/SkPolyUtils.h   |   3 -
 tests/PolyUtilsTest.cpp   |  34 ------------
 3 files changed, 149 deletions(-)

diff --git a/src/utils/SkPolyUtils.cpp b/src/utils/SkPolyUtils.cpp
index 9f08d10047..08a342a6cc 100644
--- a/src/utils/SkPolyUtils.cpp
+++ b/src/utils/SkPolyUtils.cpp
@@ -1764,115 +1764,3 @@ bool SkTriangulateSimplePolygon(const SkPoint* polygonVerts, uint16_t* indexMap,
 
     return true;
 }
-
-///////////
-
-static double crs(SkVector a, SkVector b) {
-    return a.fX * b.fY - a.fY * b.fX;
-}
-
-static int sign(SkScalar v) {
-    return v < 0 ? -1 : (v > 0);
-}
-
-struct SignTracker {
-    int fSign;
-    int fSignChanges;
-
-    void reset() {
-        fSign = 0;
-        fSignChanges = 0;
-    }
-
-    void init(int s) {
-        SkASSERT(fSignChanges == 0);
-        SkASSERT(s == 1 || s == -1 || s == 0);
-        fSign = s;
-        fSignChanges = 1;
-    }
-
-    void update(int s) {
-        if (s) {
-            if (fSign != s) {
-                fSignChanges += 1;
-                fSign = s;
-            }
-        }
-    }
-};
-
-struct ConvexTracker {
-    SkVector    fFirst, fPrev;
-    SignTracker fDSign, fCSign;
-    int         fVecCounter;
-    bool        fIsConcave;
-
-    ConvexTracker() { this->reset(); }
-
-    void reset() {
-        fPrev = {0, 0};
-        fDSign.reset();
-        fCSign.reset();
-        fVecCounter = 0;
-        fIsConcave = false;
-    }
-
-    void addVec(SkPoint p1, SkPoint p0) {
-        this->addVec(p1 - p0);
-    }
-    void addVec(SkVector v) {
-        if (v.fX == 0 && v.fY == 0) {
-            return;
-        }
-
-        fVecCounter += 1;
-        if (fVecCounter == 1) {
-            fFirst = fPrev = v;
-            fDSign.update(sign(v.fX));
-            return;
-        }
-
-        SkScalar d = v.fX;
-        SkScalar c = crs(fPrev, v);
-        int sign_c;
-        if (c) {
-            sign_c = sign(c);
-        } else {
-            if (d >= 0) {
-                sign_c = fCSign.fSign;
-            } else {
-                sign_c = -fCSign.fSign;
-            }
-        }
-
-        fDSign.update(sign(d));
-        fCSign.update(sign_c);
-        fPrev = v;
-
-        if (fDSign.fSignChanges > 3 || fCSign.fSignChanges > 1) {
-            fIsConcave = true;
-        }
-    }
-
-    void finalCross() {
-        this->addVec(fFirst);
-    }
-};
-
-bool SkIsPolyConvex_experimental(const SkPoint pts[], int count) {
-    if (count <= 3) {
-        return true;
-    }
-
-    ConvexTracker tracker;
-
-    for (int i = 0; i < count - 1; ++i) {
-        tracker.addVec(pts[i + 1], pts[i]);
-        if (tracker.fIsConcave) {
-            return false;
-        }
-    }
-    tracker.addVec(pts[0], pts[count - 1]);
-    tracker.finalCross();
-    return !tracker.fIsConcave;
-}
diff --git a/src/utils/SkPolyUtils.h b/src/utils/SkPolyUtils.h
index 7133d88240..8fdc214511 100644
--- a/src/utils/SkPolyUtils.h
+++ b/src/utils/SkPolyUtils.h
@@ -110,7 +110,4 @@ bool SkIsConvexPolygon(const SkPoint* polygonVerts, int polygonSize);
  bool SkTriangulateSimplePolygon(const SkPoint* polygonVerts, uint16_t* indexMap, int polygonSize,
                                  SkTDArray<uint16_t>* triangleIndices);
 
-// Experiment: doesn't handle really big floats (returns false), always returns true for count <= 3
-bool SkIsPolyConvex_experimental(const SkPoint[], int count);
-
 #endif
diff --git a/tests/PolyUtilsTest.cpp b/tests/PolyUtilsTest.cpp
index 89459efbb5..5bd96978bc 100644
--- a/tests/PolyUtilsTest.cpp
+++ b/tests/PolyUtilsTest.cpp
@@ -414,37 +414,3 @@ DEF_TEST(PolyUtils, reporter) {
     REPORTER_ASSERT(reporter, SkTriangulateSimplePolygon(poly.begin(), indexMap, poly.count(),
                                                           &triangleIndices));
 }
-
-struct PtSet {
-    const SkPoint*  fPts;
-    int             fN;
-};
-
-DEF_TEST(IsPolyConvex_experimental, r) {
-    #define PTSET(array)    {array, std::size(array)}
-
-    const SkPoint g0[] = { {0, 0}, {10, 0}, {10, 10}, {0, 10} };
-    const PtSet convex[] = { PTSET(g0) };
-    for (auto& set : convex) {
-        REPORTER_ASSERT(r, SkIsPolyConvex_experimental(set.fPts, set.fN));
-    }
-
-    const SkPoint b0[] = { {0, 0}, {10, 0}, {0, 10}, {10, 10} };
-    const SkPoint b1[] = {
-        {24.8219f, 8.05052f},
-        {26.0616f, 24.4895f}, {8.49582f, 16.815f},
-        {27.3047f, 7.75211f},
-        {21.927f, 27.2051f},
-    };
-    const SkPoint b2[] = {
-        {20, 20}, {20, 50}, {80, 50}, {20, 50}, {20, 80},
-    };
-    const PtSet concave[] = { PTSET(b0), PTSET(b1), PTSET(b2) };
-    for (auto& set : concave) {
-        if (SkIsPolyConvex_experimental(set.fPts, set.fN)) {
-            REPORTER_ASSERT(r, !SkIsPolyConvex_experimental(set.fPts, set.fN));
-        }
-    }
-
-}
-