src/gpu/gl/GrGLProgram.h

/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#ifndef GrGLProgram_DEFINED
#define GrGLProgram_DEFINED

#include "../GrDrawState.h"
#include "GrGLContextInfo.h"
#include "GrGLSL.h"
#include "../GrStringBuilder.h"
#include "../GrGpu.h"

#include "SkXfermode.h"

class GrBinHashKeyBuilder;

struct ShaderCodeSegments;

// optionally compile the experimental GS code. Set to GR_DEBUG
// so that debug build bots will execute the code.
#define GR_GL_EXPERIMENTAL_GS GR_DEBUG

/**
 * This class manages a GPU program and records per-program information.
 * We can specify the attribute locations so that they are constant
 * across our shaders. But the driver determines the uniform locations
 * at link time. We don't need to remember the sampler uniform location
 * because we will bind a texture slot to it and never change it
 * Uniforms are program-local so we can't rely on fHWState to hold the
 * previous uniform state after a program change.
 */
class GrGLProgram {
public:

    class CachedData;

    GrGLProgram();
    ~GrGLProgram();

    /**
     *  This is the heavy initilization routine for building a GLProgram.
     *  The result of heavy init is not stored in datamembers of GrGLProgam,
     *  but in a separate cacheable container.
     */
    bool genProgram(const GrGLContextInfo& gl,
                    CachedData* programData) const;

     /**
      * The shader may modify the blend coeffecients. Params are in/out
      */
     void overrideBlend(GrBlendCoeff* srcCoeff, GrBlendCoeff* dstCoeff) const;

    /**
     * Attribute indices. These should not overlap. Matrices consume 3 slots.
     */
    static int PositionAttributeIdx() { return 0; }
    static int TexCoordAttributeIdx(int tcIdx) { return 1 + tcIdx; }
    static int ColorAttributeIdx() { return 1 + GrDrawState::kMaxTexCoords; }
    static int CoverageAttributeIdx() {
        return 2 + GrDrawState::kMaxTexCoords;
    }
    static int EdgeAttributeIdx() { return 3 + GrDrawState::kMaxTexCoords; }

    static int ViewMatrixAttributeIdx() {
        return 4 + GrDrawState::kMaxTexCoords;
    }
    static int TextureMatrixAttributeIdx(int stage) {
        return 7 + GrDrawState::kMaxTexCoords + 3 * stage;
    }

public:

    // Parameters that affect code generation
    // These structs should be kept compact; they are the input to an
    // expensive hash key generator.
    struct ProgramDesc {
        ProgramDesc() {
            // since we use this as part of a key we can't have any unitialized
            // padding
            memset(this, 0, sizeof(ProgramDesc));
        }

        enum OutputConfig {
            // PM-color OR color with no alpha channel
            kPremultiplied_OutputConfig,
            // nonPM-color with alpha channel. Round components up after
            // dividing by alpha. Assumes output is 8 bits for r, g, and b
            kUnpremultiplied_RoundUp_OutputConfig,
            // nonPM-color with alpha channel. Round components down after
            // dividing by alpha. Assumes output is 8 bits for r, g, and b
            kUnpremultiplied_RoundDown_OutputConfig,

            kOutputConfigCnt
        };

        struct StageDesc {
            enum OptFlagBits {
                kNoPerspective_OptFlagBit       = 1 << 0,
                kIdentityMatrix_OptFlagBit      = 1 << 1,
                kCustomTextureDomain_OptFlagBit = 1 << 2,
                kIsEnabled_OptFlagBit           = 1 << 7
            };
            enum FetchMode {
                kSingle_FetchMode,
                k2x2_FetchMode,
                kConvolution_FetchMode,

                kFetchModeCnt,
            };
            /**
              Flags set based on a src texture's pixel config. The operations
              described are performed after reading a texel.
             */
            enum InConfigFlags {
                kNone_InConfigFlag                      = 0x0,

                /**
                  Swap the R and B channels. This is incompatible with
                  kSmearAlpha. It is prefereable to perform the swizzle outside
                  the shader using GL_ARB_texture_swizzle if possible rather
                  than setting this flag.
                 */
                kSwapRAndB_InConfigFlag                 = 0x1,

                /**
                 Smear alpha across all four channels. This is incompatible with
                 kSwapRAndB and kMulRGBByAlpha*. It is prefereable to perform
                 the smear outside the shader using GL_ARB_texture_swizzle if
                 possible rather than setting this flag.
                */
                kSmearAlpha_InConfigFlag                = 0x2,

                /**
                 Multiply r,g,b by a after texture reads. This flag incompatible
                 with kSmearAlpha and may only be used with FetchMode kSingle.

                 It is assumed the src texture has 8bit color components. After
                 reading the texture one version rounds up to the next multiple
                 of 1/255.0 and the other rounds down. At most one of these
                 flags may be set.
                 */
                kMulRGBByAlpha_RoundUp_InConfigFlag     =  0x4,
                kMulRGBByAlpha_RoundDown_InConfigFlag   =  0x8,

                kDummyInConfigFlag,
                kInConfigBitMask = (kDummyInConfigFlag-1) |
                                   (kDummyInConfigFlag-2)
            };
            enum CoordMapping {
                kIdentity_CoordMapping,
                kRadialGradient_CoordMapping,
                kSweepGradient_CoordMapping,
                kRadial2Gradient_CoordMapping,
                // need different shader computation when quadratic
                // eq describing the gradient degenerates to a linear eq.
                kRadial2GradientDegenerate_CoordMapping,
                kCoordMappingCnt
            };

            uint8_t fOptFlags;
            uint8_t fInConfigFlags; // bitfield of InConfigFlags values
            uint8_t fFetchMode;     // casts to enum FetchMode
            uint8_t fCoordMapping;  // casts to enum CoordMapping
            uint8_t fKernelWidth;

            GR_STATIC_ASSERT((InConfigFlags)(uint8_t)kInConfigBitMask ==
                             kInConfigBitMask);

            inline bool isEnabled() const {
                return SkToBool(fOptFlags & kIsEnabled_OptFlagBit);
            }
            inline void setEnabled(bool newValue) {
                if (newValue) {
                    fOptFlags |= kIsEnabled_OptFlagBit;
                } else {
                    fOptFlags &= ~kIsEnabled_OptFlagBit;
                }
            }
        };

        // Specifies where the intitial color comes from before the stages are
        // applied.
        enum ColorInput {
            kSolidWhite_ColorInput,
            kTransBlack_ColorInput,
            kAttribute_ColorInput,
            kUniform_ColorInput,

            kColorInputCnt
        };
        // Dual-src blending makes use of a secondary output color that can be
        // used as a per-pixel blend coeffecient. This controls whether a
        // secondary source is output and what value it holds.
        enum DualSrcOutput {
            kNone_DualSrcOutput,
            kCoverage_DualSrcOutput,
            kCoverageISA_DualSrcOutput,
            kCoverageISC_DualSrcOutput,

            kDualSrcOutputCnt
        };

        GrDrawState::VertexEdgeType fVertexEdgeType;

        // stripped of bits that don't affect prog generation
        GrVertexLayout fVertexLayout;

        StageDesc fStages[GrDrawState::kNumStages];

        // To enable experimental geometry shader code (not for use in
        // production)
#if GR_GL_EXPERIMENTAL_GS
        bool fExperimentalGS;
#endif

        uint8_t fColorInput;        // casts to enum ColorInput
        uint8_t fCoverageInput;     // casts to enum CoverageInput
        uint8_t fOutputConfig;      // casts to enum OutputConfig
        uint8_t fDualSrcOutput;     // casts to enum DualSrcOutput
        int8_t fFirstCoverageStage;
        SkBool8 fEmitsPointSize;
        SkBool8 fEdgeAAConcave;
        SkBool8 fColorMatrixEnabled;

        int8_t fEdgeAANumEdges;
        uint8_t fColorFilterXfermode;  // casts to enum SkXfermode::Mode
        int8_t fPadding[3];

    } fProgramDesc;
    GR_STATIC_ASSERT(!(sizeof(ProgramDesc) % 4));

    // for code readability
    typedef ProgramDesc::StageDesc StageDesc;

private:

    const ProgramDesc& getDesc() { return fProgramDesc; }
    const char* adjustInColor(const GrStringBuilder& inColor) const;

public:
    enum {
        kUnusedUniform = -1,
        kSetAsAttribute = 1000,
    };

    struct StageUniLocations {
        GrGLint fTextureMatrixUni;
        GrGLint fNormalizedTexelSizeUni;
        GrGLint fSamplerUni;
        GrGLint fRadial2Uni;
        GrGLint fTexDomUni;
        GrGLint fKernelUni;
        GrGLint fImageIncrementUni;
        void reset() {
            fTextureMatrixUni = kUnusedUniform;
            fNormalizedTexelSizeUni = kUnusedUniform;
            fSamplerUni = kUnusedUniform;
            fRadial2Uni = kUnusedUniform;
            fTexDomUni = kUnusedUniform;
            fKernelUni = kUnusedUniform;
            fImageIncrementUni = kUnusedUniform;
        }
    };

    struct UniLocations {
        GrGLint fViewMatrixUni;
        GrGLint fColorUni;
        GrGLint fCoverageUni;
        GrGLint fEdgesUni;
        GrGLint fColorFilterUni;
        GrGLint fColorMatrixUni;
        GrGLint fColorMatrixVecUni;
        StageUniLocations fStages[GrDrawState::kNumStages];
        void reset() {
            fViewMatrixUni = kUnusedUniform;
            fColorUni = kUnusedUniform;
            fCoverageUni = kUnusedUniform;
            fEdgesUni = kUnusedUniform;
            fColorFilterUni = kUnusedUniform;
            fColorMatrixUni = kUnusedUniform;
            fColorMatrixVecUni = kUnusedUniform;
            for (int s = 0; s < GrDrawState::kNumStages; ++s) {
                fStages[s].reset();
            }
        }
    };

    class CachedData : public ::GrNoncopyable {
    public:
        CachedData() {
        }

        ~CachedData() {
        }

        void copyAndTakeOwnership(CachedData& other) {
            memcpy(this, &other, sizeof(*this));
        }

    public:

        // IDs
        GrGLuint    fVShaderID;
        GrGLuint    fGShaderID;
        GrGLuint    fFShaderID;
        GrGLuint    fProgramID;
        // shader uniform locations (-1 if shader doesn't use them)
        UniLocations fUniLocations;

        GrMatrix  fViewMatrix;

        // these reflect the current values of uniforms
        // (GL uniform values travel with program)
        GrColor                     fColor;
        GrColor                     fCoverage;
        GrColor                     fColorFilterColor;
        GrMatrix                    fTextureMatrices[GrDrawState::kNumStages];
        // width and height used for normalized texel size
        int                         fTextureWidth[GrDrawState::kNumStages];
        int                         fTextureHeight[GrDrawState::kNumStages]; 
        GrScalar                    fRadial2CenterX1[GrDrawState::kNumStages];
        GrScalar                    fRadial2Radius0[GrDrawState::kNumStages];
        bool                        fRadial2PosRoot[GrDrawState::kNumStages];
        GrRect                      fTextureDomain[GrDrawState::kNumStages];

    private:
        enum Constants {
            kUniLocationPreAllocSize = 8
        };

    }; // CachedData

    enum Constants {
        kProgramKeySize = sizeof(ProgramDesc)
    };

    // Provide an opaque ProgramDesc
    const uint32_t* keyData() const{
        return reinterpret_cast<const uint32_t*>(&fProgramDesc);
    }

private:

    // Determines which uniforms will need to be bound.
    void genStageCode(const GrGLContextInfo& gl,
                      int stageNum,
                      const ProgramDesc::StageDesc& desc,
                      const char* fsInColor, // NULL means no incoming color
                      const char* fsOutColor,
                      const char* vsInCoord,
                      ShaderCodeSegments* segments,
                      StageUniLocations* locations) const;

    void genGeometryShader(const GrGLContextInfo& gl,
                           ShaderCodeSegments* segments) const;

    // generates code to compute coverage based on edge AA.
    void genEdgeCoverage(const GrGLContextInfo& gl,
                         GrVertexLayout layout,
                         CachedData* programData,
                         GrStringBuilder* coverageVar,
                         ShaderCodeSegments* segments) const;

    static bool CompileShaders(const GrGLContextInfo& gl,
                               const ShaderCodeSegments& segments, 
                               CachedData* programData);

    // Compiles a GL shader, returns shader ID or 0 if failed
    // params have same meaning as glShaderSource
    static GrGLuint CompileShader(const GrGLContextInfo& gl,
                                  GrGLenum type, int stringCnt,
                                  const char** strings,
                                  int* stringLengths);

    // Creates a GL program ID, binds shader attributes to GL vertex attrs, and
    // links the program
    bool bindOutputsAttribsAndLinkProgram(
                const GrGLContextInfo& gl,
                GrStringBuilder texCoordAttrNames[GrDrawState::kMaxTexCoords],
                bool bindColorOut,
                bool bindDualSrcOut,
                CachedData* programData) const;

    // Binds uniforms; initializes cache to invalid values.
    void getUniformLocationsAndInitCache(const GrGLContextInfo& gl,
                                         CachedData* programData) const;

    friend class GrGpuGLShaders;
};

#endif