Fix degenerate and near-degenerate hairlines on the gpu
R=robertphillips@google.com, bsalomon@google.com
Author: bsalomon@google.com
Review URL: https://chromiumcodereview.appspot.com/16035002
git-svn-id: http://skia.googlecode.com/svn/trunk@9279 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrAAHairLinePathRenderer.cpp b/src/gpu/GrAAHairLinePathRenderer.cpp
index 8e3ec5b..51d5a79 100644
--- a/src/gpu/GrAAHairLinePathRenderer.cpp
+++ b/src/gpu/GrAAHairLinePathRenderer.cpp
@@ -217,14 +217,14 @@
bool persp = m.hasPerspective();
for (;;) {
- GrPoint pts[4];
+ GrPoint pathPts[4];
GrPoint devPts[4];
- SkPath::Verb verb = iter.next(pts);
+ SkPath::Verb verb = iter.next(pathPts);
switch (verb) {
case SkPath::kMove_Verb:
break;
case SkPath::kLine_Verb:
- m.mapPoints(devPts, pts, 2);
+ m.mapPoints(devPts, pathPts, 2);
bounds.setBounds(devPts, 2);
bounds.outset(SK_Scalar1, SK_Scalar1);
bounds.roundOut(&ibounds);
@@ -234,34 +234,46 @@
pts[1] = devPts[1];
}
break;
- case SkPath::kQuad_Verb:
- m.mapPoints(devPts, pts, 3);
- bounds.setBounds(devPts, 3);
- bounds.outset(SK_Scalar1, SK_Scalar1);
- bounds.roundOut(&ibounds);
- if (SkIRect::Intersects(devClipBounds, ibounds)) {
- int subdiv = num_quad_subdivs(devPts);
- GrAssert(subdiv >= -1);
- if (-1 == subdiv) {
- SkPoint* pts = lines->push_back_n(4);
- pts[0] = devPts[0];
- pts[1] = devPts[1];
- pts[2] = devPts[1];
- pts[3] = devPts[2];
- } else {
- // when in perspective keep quads in src space
- SkPoint* qPts = persp ? pts : devPts;
- SkPoint* pts = quads->push_back_n(3);
- pts[0] = qPts[0];
- pts[1] = qPts[1];
- pts[2] = qPts[2];
- quadSubdivCnts->push_back() = subdiv;
- totalQuadCount += 1 << subdiv;
+ case SkPath::kQuad_Verb: {
+ SkPoint choppedPts[5];
+ // Chopping the quad helps when the quad is either degenerate or nearly degenerate.
+ // When it is degenerate it allows the approximation with lines to work since the
+ // chop point (if there is one) will be at the parabola's vertex. In the nearly
+ // degenerate the QuadUVMatrix computed for the points is almost singular which
+ // can cause rendering artifacts.
+ int n = SkChopQuadAtMaxCurvature(pathPts, choppedPts);
+ for (int i = 0; i < n; ++i) {
+ SkPoint* quadPts = choppedPts + i * 2;
+ m.mapPoints(devPts, quadPts, 3);
+ bounds.setBounds(devPts, 3);
+ bounds.outset(SK_Scalar1, SK_Scalar1);
+ bounds.roundOut(&ibounds);
+
+ if (SkIRect::Intersects(devClipBounds, ibounds)) {
+ int subdiv = num_quad_subdivs(devPts);
+ GrAssert(subdiv >= -1);
+ if (-1 == subdiv) {
+ SkPoint* pts = lines->push_back_n(4);
+ pts[0] = devPts[0];
+ pts[1] = devPts[1];
+ pts[2] = devPts[1];
+ pts[3] = devPts[2];
+ } else {
+ // when in perspective keep quads in src space
+ SkPoint* qPts = persp ? quadPts : devPts;
+ SkPoint* pts = quads->push_back_n(3);
+ pts[0] = qPts[0];
+ pts[1] = qPts[1];
+ pts[2] = qPts[2];
+ quadSubdivCnts->push_back() = subdiv;
+ totalQuadCount += 1 << subdiv;
+ }
}
}
break;
+ }
case SkPath::kCubic_Verb:
- m.mapPoints(devPts, pts, 4);
+ m.mapPoints(devPts, pathPts, 4);
bounds.setBounds(devPts, 4);
bounds.outset(SK_Scalar1, SK_Scalar1);
bounds.roundOut(&ibounds);
@@ -275,7 +287,7 @@
SkScalar tolScale =
GrPathUtils::scaleToleranceToSrc(SK_Scalar1, m,
path.getBounds());
- GrPathUtils::convertCubicToQuads(pts, tolScale, false, kDummyDir, &q);
+ GrPathUtils::convertCubicToQuads(pathPts, tolScale, false, kDummyDir, &q);
} else {
GrPathUtils::convertCubicToQuads(devPts, SK_Scalar1, false, kDummyDir, &q);
}
@@ -715,8 +727,7 @@
int rtHeight = drawState->getRenderTarget()->height();
GrIRect devClipBounds;
- target->getClip()->getConservativeBounds(drawState->getRenderTarget(),
- &devClipBounds);
+ target->getClip()->getConservativeBounds(drawState->getRenderTarget(), &devClipBounds);
SkMatrix viewM = drawState->getViewMatrix();