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fine-tune tolerance for pinchy quads in stroker

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BUG=
R=jvanverth@google.com

Review URL: https://codereview.chromium.org/22947005

git-svn-id: http://skia.googlecode.com/svn/trunk@10753 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
reed@google.com 2013-08-15 20:57:42 +00:00
parent 44d662b86a
commit 439df286c8
2 changed files with 32 additions and 2 deletions
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21
gm/aaclip.cpp
View File

@ -9,6 +9,26 @@
#include "SkCanvas.h"
#include "SkPath.h"
static void test_quadstroke(SkCanvas* canvas) {
SkPath path;
path.moveTo(6, 0);
path.quadTo(150, 150, 0, 6);
SkPaint paint;
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kStroke_Style);
canvas->translate(20, 20);
#if 1
canvas->drawPath(path, paint);
canvas->translate(100, 0);
#endif
paint.setStrokeWidth(1.01f);
canvas->drawPath(path, paint);
}
static void draw_conic(SkCanvas* canvas, SkScalar weight, const SkPaint& paint) {
SkPath path;
path.moveTo(100, 100);
@ -253,6 +273,7 @@ protected:
}
virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
if (false) { test_quadstroke(canvas); return; }
if (false) { test_conic(canvas); return; }
if (false) {
SkRect bounds;

13
src/core/SkStroke.cpp
View File

@ -30,9 +30,18 @@ static inline bool normals_too_curvy(const SkVector& norm0, SkVector& norm1) {
}
static inline bool normals_too_pinchy(const SkVector& norm0, SkVector& norm1) {
static const SkScalar kTooPinchyNormalDotProd = -SK_Scalar1 * 999 / 1000;
// if the dot-product is -1, then we are definitely too pinchy. We tweak
// that by an epsilon to ensure we have significant bits in our test
static const int kMinSigBitsForDot = 8;
static const SkScalar kDotEpsilon = FLT_EPSILON * (1 << kMinSigBitsForDot);
static const SkScalar kTooPinchyNormalDotProd = kDotEpsilon - 1;
return SkPoint::DotProduct(norm0, norm1) <= kTooPinchyNormalDotProd;
// just some sanity asserts to help document the expected range
SkASSERT(kTooPinchyNormalDotProd >= -1);
SkASSERT(kTooPinchyNormalDotProd < SkDoubleToScalar(-0.999));
SkScalar dot = SkPoint::DotProduct(norm0, norm1);
return dot <= kTooPinchyNormalDotProd;
}
static bool set_normal_unitnormal(const SkPoint& before, const SkPoint& after,