1 files changed, 67 insertions, 0 deletions

diff --git a/src/gpu/effects/GrCircleEffect.fp b/src/gpu/effects/GrCircleEffect.fp
new file mode 100644
index 0000000000..3f0b85017e
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+++ b/src/gpu/effects/GrCircleEffect.fp
@@ -0,0 +1,67 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+layout(key) in int edgeType;
+in vec2 center;
+in float radius;
+
+vec2 prevCenter;
+float prevRadius = -1;
+// The circle uniform is (center.x, center.y, radius + 0.5, 1 / (radius + 0.5)) for regular
+// fills and (..., radius - 0.5, 1 / (radius - 0.5)) for inverse fills.
+uniform vec4 circle;
+
+@optimizationFlags { kCompatibleWithCoverageAsAlpha_OptimizationFlag }
+
+@setData(pdman) {
+    if (radius != prevRadius || center != prevCenter) {
+        SkScalar effectiveRadius = radius;
+        if (GrProcessorEdgeTypeIsInverseFill((GrPrimitiveEdgeType) edgeType)) {
+            effectiveRadius -= 0.5f;
+        } else {
+            effectiveRadius += 0.5f;
+        }
+        pdman.set4f(circle, center.fX, center.fY, effectiveRadius,
+                    SkScalarInvert(effectiveRadius));
+        prevCenter = center;
+        prevRadius = radius;
+    }
+}
+
+void main() {
+    // TODO: Right now the distance to circle caclulation is performed in a space normalized to the
+    // radius and then denormalized. This is to prevent overflow on devices that have a "real"
+    // mediump. It'd be nice to only do this on mediump devices.
+    float d;
+    if (edgeType == 2 /* kInverseFillBW_GrProcessorEdgeType */ ||
+        edgeType == 3 /* kInverseFillAA_GrProcessorEdgeType */) {
+        d = (length((circle.xy - sk_FragCoord.xy) * circle.w) - 1.0) * circle.z;
+    } else {
+        d = (1.0 - length((circle.xy - sk_FragCoord.xy) *  circle.w)) * circle.z;
+    }
+    if (edgeType == 1 /* kFillAA_GrProcessorEdgeType */ ||
+        edgeType == 3 /* kInverseFillAA_GrProcessorEdgeType */ ||
+        edgeType == 4 /* kHairlineAA_GrProcessorEdgeType */) {
+        d = clamp(d, 0.0, 1.0);
+    } else {
+        d = d > 0.5 ? 1.0 : 0.0;
+    }
+
+    sk_OutColor = sk_InColor * d;
+}
+
+@test(testData) {
+    SkPoint center;
+    center.fX = testData->fRandom->nextRangeScalar(0.f, 1000.f);
+    center.fY = testData->fRandom->nextRangeScalar(0.f, 1000.f);
+    SkScalar radius = testData->fRandom->nextRangeF(0.f, 1000.f);
+    GrPrimitiveEdgeType et;
+    do {
+        et = (GrPrimitiveEdgeType) testData->fRandom->nextULessThan(kGrProcessorEdgeTypeCnt);
+    } while (kHairlineAA_GrProcessorEdgeType == et);
+    return GrCircleEffect::Make(et, center, radius);
+}
\ No newline at end of file