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Add some convexity checks to shadow code.

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To address https://github.com/flutter/flutter/issues/11221.

Change-Id: I5ccd7f9eb2f3ee0d168aa4ca5474bfdfba14ca9c
Reviewed-on: https://skia-review.googlesource.com/24124
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
This commit is contained in:
Jim Van Verth 2017-07-18 14:13:45 -04:00 committed by Skia Commit-Bot
parent 3b92b6907a
commit b55eb28a17
2 changed files with 34 additions and 16 deletions
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11
src/utils/SkInsetConvexPolygon.cpp
View File

@ -137,7 +137,6 @@ static bool compute_intersection(const InsetSegment& s0, const InsetSegment& s1,
return true;
}
#ifdef SK_DEBUG
static bool is_convex(const SkTDArray<SkPoint>& poly) {
if (poly.count() <= 3) {
return true;
@ -161,7 +160,6 @@ static bool is_convex(const SkTDArray<SkPoint>& poly) {
return true;
}
#endif
// The objective here is to inset all of the edges by the given distance, and then
// remove any invalid inset edges by detecting right-hand turns. In a ccw polygon,
@ -198,6 +196,12 @@ bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize
SkAutoSTMalloc<64, EdgeData> edgeData(inputPolygonSize);
for (int i = 0; i < inputPolygonSize; ++i) {
int j = (i + 1) % inputPolygonSize;
int k = (i + 2) % inputPolygonSize;
// check for convexity just to be sure
if (compute_side(inputPolygonVerts[i], inputPolygonVerts[j],
inputPolygonVerts[k])*winding < 0) {
return false;
}
SkOffsetSegment(inputPolygonVerts[i], inputPolygonVerts[j],
insetDistanceFunc(i), insetDistanceFunc(j),
winding,
@ -284,7 +288,6 @@ bool SkInsetConvexPolygon(const SkPoint* inputPolygonVerts, int inputPolygonSize
kCleanupTolerance)) {
insetPolygon->pop();
}
SkASSERT(is_convex(*insetPolygon));
return (insetPolygon->count() >= 3);
return (insetPolygon->count() >= 3 && is_convex(*insetPolygon));
}

39
src/utils/SkShadowTessellator.cpp
View File

@ -749,7 +749,7 @@ private:
int getClosestUmbraPoint(const SkPoint& point);
void handleLine(const SkPoint& p) override;
void handlePolyPoint(const SkPoint& p);
bool handlePolyPoint(const SkPoint& p);
void mapPoints(SkScalar scale, const SkVector& xlate, SkPoint* pts, int count);
bool addInnerPoint(const SkPoint& pathPoint);
@ -890,7 +890,9 @@ SkSpotShadowTessellator::SkSpotShadowTessellator(const SkPath& path, const SkMat
}
fCurrUmbraPoint = 0;
for (int i = 0; i < fPathPolygon.count(); ++i) {
this->handlePolyPoint(fPathPolygon[i]);
if (!this->handlePolyPoint(fPathPolygon[i])) {
return;
}
}
if (!this->indexCount()) {
@ -1195,10 +1197,14 @@ static bool duplicate_pt(const SkPoint& p0, const SkPoint& p1) {
return distSq < kCloseSqd;
}
static bool is_collinear(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2) {
static SkScalar perp_dot(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2) {
SkVector v0 = p1 - p0;
SkVector v1 = p2 - p0;
return (SkScalarNearlyZero(v0.cross(v1)));
return v0.cross(v1);
}
static bool is_collinear(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2) {
return (SkScalarNearlyZero(perp_dot(p0, p1, p2)));
}
void SkSpotShadowTessellator::handleLine(const SkPoint& p) {
@ -1224,21 +1230,19 @@ void SkSpotShadowTessellator::handleLine(const SkPoint& p) {
}
}
void SkSpotShadowTessellator::handlePolyPoint(const SkPoint& p) {
bool SkSpotShadowTessellator::handlePolyPoint(const SkPoint& p) {
if (fInitPoints.count() < 2) {
*fInitPoints.push() = p;
return;
return true;
}
if (fInitPoints.count() == 2) {
// determine if cw or ccw
SkVector v0 = fInitPoints[1] - fInitPoints[0];
SkVector v1 = p - fInitPoints[0];
SkScalar perpDot = v0.cross(v1);
SkScalar perpDot = perp_dot(fInitPoints[0], fInitPoints[1], p);
if (SkScalarNearlyZero(perpDot)) {
// nearly parallel, just treat as straight line and continue
fInitPoints[1] = p;
return;
return true;
}
// if perpDot > 0, winding is ccw
@ -1248,7 +1252,7 @@ void SkSpotShadowTessellator::handlePolyPoint(const SkPoint& p) {
if (!compute_normal(fInitPoints[0], fInitPoints[1], fDirection, &fFirstOutset)) {
// first two points are incident, make the third point the second and continue
fInitPoints[1] = p;
return;
return true;
}
fFirstOutset *= fRadius;
@ -1263,7 +1267,8 @@ void SkSpotShadowTessellator::handlePolyPoint(const SkPoint& p) {
if (!fTransparent) {
SkPoint clipPoint;
bool isOutside = this->clipUmbraPoint(fPositions[fFirstVertexIndex], fCentroid, &clipPoint);
bool isOutside = this->clipUmbraPoint(fPositions[fFirstVertexIndex],
fCentroid, &clipPoint);
if (isOutside) {
*fPositions.push() = clipPoint;
*fColors.push() = fUmbraColor;
@ -1281,12 +1286,22 @@ void SkSpotShadowTessellator::handlePolyPoint(const SkPoint& p) {
*fInitPoints.push() = p;
}
// if concave, abort
SkScalar perpDot = perp_dot(fInitPoints[1], fInitPoints[2], p);
if (fDirection*perpDot > 0) {
return false;
}
SkVector normal;
if (compute_normal(fPrevPoint, p, fDirection, &normal)) {
normal *= fRadius;
this->addArc(normal, true);
this->addEdge(p, normal);
fInitPoints[1] = fInitPoints[2];
fInitPoints[2] = p;
}
return true;
}
bool SkSpotShadowTessellator::addInnerPoint(const SkPoint& pathPoint) {