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1 /*
2  * Copyright 2021 Google LLC.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #include "src/gpu/effects/GrModulateAtlasCoverageEffect.h"
9 
10 #include "src/gpu/GrDynamicAtlas.h"
11 #include "src/gpu/effects/GrTextureEffect.h"
12 
GrModulateAtlasCoverageEffect(Flags flags,std::unique_ptr<GrFragmentProcessor> inputFP,GrSurfaceProxyView atlasView,const SkMatrix & devToAtlasMatrix,const SkIRect & devIBounds)13 GrModulateAtlasCoverageEffect::GrModulateAtlasCoverageEffect(
14         Flags flags,
15         std::unique_ptr<GrFragmentProcessor> inputFP,
16         GrSurfaceProxyView atlasView,
17         const SkMatrix& devToAtlasMatrix,
18         const SkIRect& devIBounds)
19         : GrFragmentProcessor(kTessellate_GrModulateAtlasCoverageEffect_ClassID,
20                               kCompatibleWithCoverageAsAlpha_OptimizationFlag)
21         , fFlags(flags)
22         , fBounds((fFlags & Flags::kCheckBounds) ? devIBounds : SkIRect{0,0,0,0}) {
23     this->registerChild(std::move(inputFP));
24     this->registerChild(GrTextureEffect::Make(std::move(atlasView), kUnknown_SkAlphaType,
25                                               devToAtlasMatrix, GrSamplerState::Filter::kNearest),
26                         SkSL::SampleUsage::Explicit());
27 }
28 
GrModulateAtlasCoverageEffect(const GrModulateAtlasCoverageEffect & that)29 GrModulateAtlasCoverageEffect::GrModulateAtlasCoverageEffect(
30         const GrModulateAtlasCoverageEffect& that)
31         : GrFragmentProcessor(that)
32         , fFlags(that.fFlags)
33         , fBounds(that.fBounds) {}
34 
35 std::unique_ptr<GrFragmentProcessor::ProgramImpl>
onMakeProgramImpl() const36 GrModulateAtlasCoverageEffect::onMakeProgramImpl() const {
37     class Impl : public ProgramImpl {
38         void emitCode(EmitArgs& args) override {
39             auto fp = args.fFp.cast<GrModulateAtlasCoverageEffect>();
40             auto f = args.fFragBuilder;
41             auto uniHandler = args.fUniformHandler;
42             SkString inputColor = this->invokeChild(0, args);
43             f->codeAppend("half coverage = 0;");
44             if (fp.fFlags & Flags::kCheckBounds) {
45                 const char* boundsName;
46                 fBoundsUniform = uniHandler->addUniform(&fp, kFragment_GrShaderFlag,
47                                                         kFloat4_GrSLType, "bounds", &boundsName);
48                 // Are we inside the path's valid atlas bounds?
49                 f->codeAppendf("if (all(greaterThan(sk_FragCoord.xy, %s.xy)) && "
50                                    "all(lessThan(sk_FragCoord.xy, %s.zw))) ",
51                                boundsName, boundsName);
52             }
53             f->codeAppendf("{");
54             SkString atlasCoverage = this->invokeChild(1, args, "sk_FragCoord.xy");
55             f->codeAppendf("coverage = %s.a;", atlasCoverage.c_str());
56             f->codeAppendf("}");
57             const char* coverageMaybeInvertName;
58             fCoverageMaybeInvertUniform = uniHandler->addUniform(&fp, kFragment_GrShaderFlag,
59                                                                  kHalf2_GrSLType, "coverageInvert",
60                                                                  &coverageMaybeInvertName);
61             // Invert coverage, if needed.
62             f->codeAppendf("coverage = coverage * %s.x + %s.y;",
63                            coverageMaybeInvertName, coverageMaybeInvertName);
64             f->codeAppendf("return %s * coverage;", inputColor.c_str());
65         }
66 
67     private:
68         void onSetData(const GrGLSLProgramDataManager& pdman,
69                        const GrFragmentProcessor& processor) override {
70             auto fp = processor.cast<GrModulateAtlasCoverageEffect>();
71             if (fp.fFlags & Flags::kCheckBounds) {
72                 pdman.set4fv(fBoundsUniform, 1, SkRect::Make(fp.fBounds).asScalars());
73             }
74             if (fp.fFlags & Flags::kInvertCoverage) {
75                 pdman.set2f(fCoverageMaybeInvertUniform, -1, 1);  // -1*coverage + 1 = 1 - coverage.
76             } else {
77                 pdman.set2f(fCoverageMaybeInvertUniform, 1, 0);  // 1*coverage + 0 = coverage.
78             }
79         }
80         UniformHandle fBoundsUniform;
81         UniformHandle fCoverageMaybeInvertUniform;
82     };
83 
84     return std::make_unique<Impl>();
85 }
86