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#ifndef GrGLSLFragmentShaderBuilder_DEFINED
9#define GrGLSLFragmentShaderBuilder_DEFINED
10
11#include "src/gpu/GrBlend.h"
12#include "src/gpu/GrFragmentProcessor.h"
13#include "src/gpu/GrProcessor.h"
14#include "src/gpu/glsl/GrGLSLShaderBuilder.h"
15
16class GrRenderTarget;
17class GrGLSLVarying;
18
19/*
20 * This class is used by fragment processors to build their fragment code.
21 */
22class GrGLSLFPFragmentBuilder : virtual public GrGLSLShaderBuilder {
23public:
24    /** Appease the compiler; the derived class initializes GrGLSLShaderBuilder. */
25    GrGLSLFPFragmentBuilder() : GrGLSLShaderBuilder(nullptr) {
26        // Suppress unused warning error
27        (void) fPadding;
28    }
29
30    enum class ScopeFlags {
31        // Every fragment will always execute this code, and will do it exactly once.
32        kTopLevel = 0,
33        // Either all fragments in a given primitive, or none, will execute this code.
34        kInsidePerPrimitiveBranch = (1 << 0),
35        // Any given fragment may or may not execute this code.
36        kInsidePerPixelBranch = (1 << 1),
37        // This code will be executed more than once.
38        kInsideLoop = (1 << 2)
39    };
40
41    virtual void forceHighPrecision() = 0;
42
43    /** Returns the variable name that holds the color of the destination pixel. This may be nullptr
44     * if no effect advertised that it will read the destination. */
45    virtual const char* dstColor() = 0;
46
47private:
48    // WARNING: LIke GrRenderTargetProxy, changes to this can cause issues in ASAN. This is caused
49    // by GrGLSLProgramBuilder's SkTBlockLists requiring 16 byte alignment, but since
50    // GrGLSLFragmentShaderBuilder has a virtual diamond hierarchy, ASAN requires all this pointers
51    // to start aligned, even though clang is already correctly offsetting the individual fields
52    // that require the larger alignment. In the current world, this extra padding is sufficient to
53    // correctly initialize GrGLSLXPFragmentBuilder second.
54    char fPadding[4] = {};
55};
56
57GR_MAKE_BITFIELD_CLASS_OPS(GrGLSLFPFragmentBuilder::ScopeFlags)
58
59/*
60 * This class is used by Xfer processors to build their fragment code.
61 */
62class GrGLSLXPFragmentBuilder : virtual public GrGLSLShaderBuilder {
63public:
64    /** Appease the compiler; the derived class initializes GrGLSLShaderBuilder. */
65    GrGLSLXPFragmentBuilder() : GrGLSLShaderBuilder(nullptr) {}
66
67    virtual bool hasCustomColorOutput() const = 0;
68    virtual bool hasSecondaryOutput() const = 0;
69
70    /** Returns the variable name that holds the color of the destination pixel. This may be nullptr
71     * if no effect advertised that it will read the destination. */
72    virtual const char* dstColor() = 0;
73
74    /** Adds any necessary layout qualifiers in order to legalize the supplied blend equation with
75        this shader. It is only legal to call this method with an advanced blend equation, and only
76        if these equations are supported. */
77    virtual void enableAdvancedBlendEquationIfNeeded(GrBlendEquation) = 0;
78};
79
80/*
81 * This class implements the various fragment builder interfaces.
82 */
83class GrGLSLFragmentShaderBuilder : public GrGLSLFPFragmentBuilder, public GrGLSLXPFragmentBuilder {
84public:
85    GrGLSLFragmentShaderBuilder(GrGLSLProgramBuilder* program);
86
87    // Shared FP/XP interface.
88    const char* dstColor() override;
89
90    // GrGLSLFPFragmentBuilder interface.
91    void forceHighPrecision() override { fForceHighPrecision = true; }
92
93    // GrGLSLXPFragmentBuilder interface.
94    bool hasCustomColorOutput() const override { return SkToBool(fCustomColorOutput); }
95    bool hasSecondaryOutput() const override { return fHasSecondaryOutput; }
96    void enableAdvancedBlendEquationIfNeeded(GrBlendEquation) override;
97
98private:
99    // Private public interface, used by GrGLProgramBuilder to build a fragment shader
100    void enableCustomOutput();
101    void enableSecondaryOutput();
102    const char* getPrimaryColorOutputName() const;
103    const char* getSecondaryColorOutputName() const;
104    bool primaryColorOutputIsInOut() const;
105
106#ifdef SK_DEBUG
107    // As GLSLProcessors emit code, there are some conditions we need to verify.  We use the below
108    // state to track this.  The reset call is called per processor emitted.
109    bool fHasReadDstColorThisStage_DebugOnly = false;
110
111    void debugOnly_resetPerStageVerification() {
112        fHasReadDstColorThisStage_DebugOnly = false;
113    }
114#endif
115
116    static const char* DeclaredColorOutputName() { return "sk_FragColor"; }
117    static const char* DeclaredSecondaryColorOutputName() { return "fsSecondaryColorOut"; }
118
119    GrSurfaceOrigin getSurfaceOrigin() const;
120
121    void onFinalize() override;
122
123    inline static constexpr const char kDstColorName[] = "_dstColor";
124
125    GrShaderVar* fCustomColorOutput = nullptr;
126
127    bool fSetupFragPosition = false;
128    bool fHasSecondaryOutput = false;
129    bool fHasModifiedSampleMask = false;
130    bool fForceHighPrecision = false;
131
132    friend class GrGLSLProgramBuilder;
133    friend class GrGLProgramBuilder;
134    friend class GrVkPipelineStateBuilder;
135};
136
137#endif
138