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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/gpu/effects/GrConvexPolyEffect.h"
#include "src/core/SkPathPriv.h"
#include "src/gpu/KeyBuilder.h"
#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
#include "src/gpu/glsl/GrGLSLProgramDataManager.h"
#include "src/gpu/glsl/GrGLSLUniformHandler.h"
#include "src/sksl/dsl/priv/DSLFPs.h"
//////////////////////////////////////////////////////////////////////////////
GrFPResult GrConvexPolyEffect::Make(std::unique_ptr<GrFragmentProcessor> inputFP,
GrClipEdgeType type, const SkPath& path) {
if (path.getSegmentMasks() != SkPath::kLine_SegmentMask || !path.isConvex()) {
return GrFPFailure(std::move(inputFP));
}
SkPathFirstDirection dir = SkPathPriv::ComputeFirstDirection(path);
// The only way this should fail is if the clip is effectively a infinitely thin line. In that
// case nothing is inside the clip. It'd be nice to detect this at a higher level and either
// skip the draw or omit the clip element.
if (dir == SkPathFirstDirection::kUnknown) {
if (GrClipEdgeTypeIsInverseFill(type)) {
return GrFPSuccess(
GrFragmentProcessor::ModulateRGBA(std::move(inputFP), SK_PMColor4fWHITE));
}
// This could use ConstColor instead of ModulateRGBA but it would trigger a debug print
// about a coverage processor not being compatible with the alpha-as-coverage optimization.
// We don't really care about this unlikely case so we just use ModulateRGBA to suppress
// the print.
return GrFPSuccess(
GrFragmentProcessor::ModulateRGBA(std::move(inputFP), SK_PMColor4fTRANSPARENT));
}
SkScalar edges[3 * kMaxEdges];
SkPoint pts[4];
SkPath::Verb verb;
SkPath::Iter iter(path, true);
// SkPath considers itself convex so long as there is a convex contour within it,
// regardless of any degenerate contours such as a string of moveTos before it.
// Iterate here to consume any degenerate contours and only process the points
// on the actual convex contour.
int n = 0;
while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
switch (verb) {
case SkPath::kMove_Verb:
case SkPath::kClose_Verb:
break;
case SkPath::kLine_Verb: {
if (n >= kMaxEdges) {
return GrFPFailure(std::move(inputFP));
}
if (pts[0] != pts[1]) {
SkVector v = pts[1] - pts[0];
v.normalize();
if (SkPathFirstDirection::kCCW == dir) {
edges[3 * n] = v.fY;
edges[3 * n + 1] = -v.fX;
} else {
edges[3 * n] = -v.fY;
edges[3 * n + 1] = v.fX;
}
edges[3 * n + 2] = -(edges[3 * n] * pts[1].fX + edges[3 * n + 1] * pts[1].fY);
++n;
}
break;
}
default:
// Non-linear segment so not a polygon.
return GrFPFailure(std::move(inputFP));
}
}
if (path.isInverseFillType()) {
type = GrInvertClipEdgeType(type);
}
return GrConvexPolyEffect::Make(std::move(inputFP), type, n, edges);
}
GrConvexPolyEffect::~GrConvexPolyEffect() {}
void GrConvexPolyEffect::onAddToKey(const GrShaderCaps& caps, skgpu::KeyBuilder* b) const {
static_assert(kGrClipEdgeTypeCnt <= 8);
uint32_t key = (fEdgeCount << 3) | static_cast<int>(fEdgeType);
b->add32(key);
}
std::unique_ptr<GrFragmentProcessor::ProgramImpl> GrConvexPolyEffect::onMakeProgramImpl() const {
class Impl : public ProgramImpl {
public:
void emitCode(EmitArgs& args) override {
const GrConvexPolyEffect& cpe = args.fFp.cast<GrConvexPolyEffect>();
using namespace SkSL::dsl;
StartFragmentProcessor(this, &args);
GlobalVar edgeArray(kUniform_Modifier, Array(kHalf3_Type, cpe.fEdgeCount), "edgeArray");
Declare(edgeArray);
fEdgeUniform = VarUniformHandle(edgeArray);
Var alpha(kHalf_Type, "alpha", 1);
Declare(alpha);
Var edge(kHalf_Type, "edge");
Declare(edge);
for (int i = 0; i < cpe.fEdgeCount; ++i) {
edge = Dot(edgeArray[i], Half3(Swizzle(sk_FragCoord(), X, Y, ONE)));
if (GrClipEdgeTypeIsAA(cpe.fEdgeType)) {
edge = Saturate(edge);
} else {
edge = Select(edge >= 0.5, 1.0, 0.0);
}
alpha *= edge;
}
if (GrClipEdgeTypeIsInverseFill(cpe.fEdgeType)) {
alpha = 1.0 - alpha;
}
Return(SampleChild(0) * alpha);
EndFragmentProcessor();
}
private:
void onSetData(const GrGLSLProgramDataManager& pdman,
const GrFragmentProcessor& fp) override {
const GrConvexPolyEffect& cpe = fp.cast<GrConvexPolyEffect>();
size_t n = 3*cpe.fEdgeCount;
if (!std::equal(fPrevEdges.begin(), fPrevEdges.begin() + n, cpe.fEdges.begin())) {
pdman.set3fv(fEdgeUniform, cpe.fEdgeCount, cpe.fEdges.data());
std::copy_n(cpe.fEdges.begin(), n, fPrevEdges.begin());
}
}
GrGLSLProgramDataManager::UniformHandle fEdgeUniform;
std::array<float, 3 * GrConvexPolyEffect::kMaxEdges> fPrevEdges = {SK_FloatNaN};
};
return std::make_unique<Impl>();
}
GrConvexPolyEffect::GrConvexPolyEffect(std::unique_ptr<GrFragmentProcessor> inputFP,
GrClipEdgeType edgeType,
int n,
const float edges[])
: INHERITED(kGrConvexPolyEffect_ClassID,
ProcessorOptimizationFlags(inputFP.get()) &
kCompatibleWithCoverageAsAlpha_OptimizationFlag)
, fEdgeType(edgeType)
, fEdgeCount(n) {
// Factory function should have already ensured this.
SkASSERT(n <= kMaxEdges);
std::copy_n(edges, 3*n, fEdges.begin());
// Outset the edges by 0.5 so that a pixel with center on an edge is 50% covered in the AA case
// and 100% covered in the non-AA case.
for (int i = 0; i < n; ++i) {
fEdges[3 * i + 2] += SK_ScalarHalf;
}
this->registerChild(std::move(inputFP));
}
GrConvexPolyEffect::GrConvexPolyEffect(const GrConvexPolyEffect& that)
: INHERITED(that)
, fEdgeType(that.fEdgeType)
, fEdgeCount(that.fEdgeCount) {
std::copy_n(that.fEdges.begin(), 3*that.fEdgeCount, fEdges.begin());
}
std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::clone() const {
return std::unique_ptr<GrFragmentProcessor>(new GrConvexPolyEffect(*this));
}
bool GrConvexPolyEffect::onIsEqual(const GrFragmentProcessor& other) const {
const GrConvexPolyEffect& cpe = other.cast<GrConvexPolyEffect>();
int n = 3*cpe.fEdgeCount;
return cpe.fEdgeType == fEdgeType &&
cpe.fEdgeCount == fEdgeCount &&
std::equal(cpe.fEdges.begin(), cpe.fEdges.begin() + n, fEdges.begin());
}
//////////////////////////////////////////////////////////////////////////////
GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrConvexPolyEffect);
#if GR_TEST_UTILS
std::unique_ptr<GrFragmentProcessor> GrConvexPolyEffect::TestCreate(GrProcessorTestData* d) {
int count = d->fRandom->nextULessThan(kMaxEdges) + 1;
SkScalar edges[kMaxEdges * 3];
for (int i = 0; i < 3 * count; ++i) {
edges[i] = d->fRandom->nextSScalar1();
}
bool success;
std::unique_ptr<GrFragmentProcessor> fp = d->inputFP();
do {
GrClipEdgeType edgeType =
static_cast<GrClipEdgeType>(d->fRandom->nextULessThan(kGrClipEdgeTypeCnt));
std::tie(success, fp) = GrConvexPolyEffect::Make(std::move(fp), edgeType, count, edges);
} while (!success);
return fp;
}
#endif