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/*
* 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 GrClipEdgeType edgeType;
in float2 center;
in float2 radii;
float2 prevCenter;
float2 prevRadii = float2(-1);
// The ellipse uniform is (center.x, center.y, 1 / rx^2, 1 / ry^2)
// The last two terms can underflow when float != fp32, so we also provide a workaround.
uniform float4 ellipse;
bool useScale = !sk_Caps.floatIs32Bits;
layout(when=useScale) uniform float2 scale;
@optimizationFlags { kCompatibleWithCoverageAsAlpha_OptimizationFlag }
@setData(pdman) {
if (radii != prevRadii || center != prevCenter) {
float invRXSqd;
float invRYSqd;
// If we're using a scale factor to work around precision issues, choose the larger radius
// as the scale factor. The inv radii need to be pre-adjusted by the scale factor.
if (scale.isValid()) {
if (radii.fX > radii.fY) {
invRXSqd = 1.f;
invRYSqd = (radii.fX * radii.fX) /
(radii.fY * radii.fY);
pdman.set2f(scale, radii.fX, 1.f / radii.fX);
} else {
invRXSqd = (radii.fY * radii.fY) /
(radii.fX * radii.fX);
invRYSqd = 1.f;
pdman.set2f(scale, radii.fY, 1.f / radii.fY);
}
} else {
invRXSqd = 1.f / (radii.fX * radii.fX);
invRYSqd = 1.f / (radii.fY * radii.fY);
}
pdman.set4f(ellipse, center.fX, center.fY, invRXSqd, invRYSqd);
prevCenter = center;
prevRadii = radii;
}
}
void main() {
// d is the offset to the ellipse center
float2 d = sk_FragCoord.xy - ellipse.xy;
// If we're on a device with a "real" mediump then we'll do the distance computation in a space
// that is normalized by the larger radius. The scale uniform will be scale, 1/scale. The
// inverse squared radii uniform values are already in this normalized space. The center is
// not.
@if (useScale) {
d *= scale.y;
}
float2 Z = d * ellipse.zw;
// implicit is the evaluation of (x/rx)^2 + (y/ry)^2 - 1.
float implicit = dot(Z, d) - 1;
// grad_dot is the squared length of the gradient of the implicit.
float grad_dot = 4 * dot(Z, Z);
// Avoid calling inversesqrt on zero.
grad_dot = max(grad_dot, 1e-4);
float approx_dist = implicit * inversesqrt(grad_dot);
@if (useScale) {
approx_dist *= scale.x;
}
half alpha;
@switch (edgeType) {
case GrClipEdgeType::kFillBW:
alpha = approx_dist > 0.0 ? 0.0 : 1.0;
break;
case GrClipEdgeType::kFillAA:
alpha = clamp(0.5 - approx_dist, 0.0, 1.0);
break;
case GrClipEdgeType::kInverseFillBW:
alpha = approx_dist > 0.0 ? 1.0 : 0.0;
break;
case GrClipEdgeType::kInverseFillAA:
alpha = clamp(0.5 + approx_dist, 0.0, 1.0);
break;
default:
// hairline not supported
discard;
}
sk_OutColor = sk_InColor * alpha;
}
@test(testData) {
SkPoint center;
center.fX = testData->fRandom->nextRangeScalar(0.f, 1000.f);
center.fY = testData->fRandom->nextRangeScalar(0.f, 1000.f);
SkScalar rx = testData->fRandom->nextRangeF(0.f, 1000.f);
SkScalar ry = testData->fRandom->nextRangeF(0.f, 1000.f);
GrClipEdgeType et;
do {
et = (GrClipEdgeType) testData->fRandom->nextULessThan(kGrClipEdgeTypeCnt);
} while (GrClipEdgeType::kHairlineAA == et);
return GrEllipseEffect::Make(et, center, SkPoint::Make(rx, ry));
}
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