1/*
2 * Copyright 2014 Google Inc.
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 "effects/GrDisableColorXP.h"
9#include "GrProcessor.h"
10#include "gl/GrGLXferProcessor.h"
11#include "gl/builders/GrGLFragmentShaderBuilder.h"
12#include "gl/builders/GrGLProgramBuilder.h"
13
14/**
15 * This xfer processor disables color writing. Thus color and coverage and ignored and no blending
16 * occurs. This XP is usful for things like stenciling.
17 */
18class DisableColorXP : public GrXferProcessor {
19public:
20    static GrXferProcessor* Create() {
21        return SkNEW(DisableColorXP);
22    }
23
24    ~DisableColorXP() override {};
25
26    const char* name() const override { return "Disable Color"; }
27
28    GrGLXferProcessor* createGLInstance() const override;
29
30    bool hasSecondaryOutput() const override { return false; }
31
32private:
33    DisableColorXP();
34
35    GrXferProcessor::OptFlags onGetOptimizations(const GrProcOptInfo& colorPOI,
36                                                 const GrProcOptInfo& coveragePOI,
37                                                 bool doesStencilWrite,
38                                                 GrColor* color,
39                                                 const GrDrawTargetCaps& caps) override {
40        return GrXferProcessor::kIgnoreColor_OptFlag | GrXferProcessor::kIgnoreCoverage_OptFlag;
41    }
42
43    void onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override;
44
45    void onGetBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const override;
46
47    bool onIsEqual(const GrXferProcessor& xpBase) const override {
48        return true;
49    }
50
51    typedef GrXferProcessor INHERITED;
52};
53
54///////////////////////////////////////////////////////////////////////////////
55
56class GLDisableColorXP : public GrGLXferProcessor {
57public:
58    GLDisableColorXP(const GrProcessor&) {}
59
60    ~GLDisableColorXP() override {}
61
62    static void GenKey(const GrProcessor&, const GrGLSLCaps&, GrProcessorKeyBuilder*) {}
63
64private:
65    void onEmitCode(const EmitArgs& args) override {
66        // This emit code should be empty. However, on the nexus 6 there is a driver bug where if
67        // you do not give gl_FragColor a value, the gl context is lost and we end up drawing
68        // nothing. So this fix just sets the gl_FragColor arbitrarily to 0.
69        GrGLXPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
70        fsBuilder->codeAppendf("%s = vec4(0);", args.fOutputPrimary);
71    }
72
73    void onSetData(const GrGLProgramDataManager&, const GrXferProcessor&) override {}
74
75    typedef GrGLXferProcessor INHERITED;
76};
77
78///////////////////////////////////////////////////////////////////////////////
79
80DisableColorXP::DisableColorXP() {
81    this->initClassID<DisableColorXP>();
82}
83
84void DisableColorXP::onGetGLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const {
85    GLDisableColorXP::GenKey(*this, caps, b);
86}
87
88GrGLXferProcessor* DisableColorXP::createGLInstance() const {
89    return SkNEW_ARGS(GLDisableColorXP, (*this));
90}
91
92void DisableColorXP::onGetBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const {
93    blendInfo->fWriteColor = false;
94}
95
96///////////////////////////////////////////////////////////////////////////////
97
98GrDisableColorXPFactory::GrDisableColorXPFactory() {
99    this->initClassID<GrDisableColorXPFactory>();
100}
101
102GrXferProcessor*
103GrDisableColorXPFactory::onCreateXferProcessor(const GrDrawTargetCaps& caps,
104                                               const GrProcOptInfo& colorPOI,
105                                               const GrProcOptInfo& covPOI,
106                                               const GrDeviceCoordTexture* dstCopy) const {
107    return DisableColorXP::Create();
108}
109
110GR_DEFINE_XP_FACTORY_TEST(GrDisableColorXPFactory);
111
112GrXPFactory* GrDisableColorXPFactory::TestCreate(SkRandom* random,
113                                                  GrContext*,
114                                                  const GrDrawTargetCaps&,
115                                                  GrTexture*[]) {
116    return GrDisableColorXPFactory::Create();
117}
118
119