skia2/src/effects/SkArithmeticMode_gpu.cpp

/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkArithmeticMode_gpu.h"

#if SK_SUPPORT_GPU
#include "GrContext.h"
#include "GrFragmentProcessor.h"
#include "GrInvariantOutput.h"
#include "GrProcessor.h"
#include "GrTexture.h"
#include "gl/GrGLCaps.h"
#include "gl/GrGLProcessor.h"
#include "gl/GrGLProgramDataManager.h"
#include "gl/builders/GrGLProgramBuilder.h"

static const bool gUseUnpremul = false;

static void add_arithmetic_code(GrGLFPFragmentBuilder* fsBuilder,
                                const char* inputColor,
                                const char* dstColor,
                                const char* outputColor,
                                const char* kUni,
                                bool enforcePMColor) {
    // We don't try to optimize for this case at all
    if (NULL == inputColor) {
        fsBuilder->codeAppend("const vec4 src = vec4(1);");
    } else {
        fsBuilder->codeAppendf("vec4 src = %s;", inputColor);
        if (gUseUnpremul) {
            fsBuilder->codeAppend("src.rgb = clamp(src.rgb / src.a, 0.0, 1.0);");
        }
    }

    fsBuilder->codeAppendf("vec4 dst = %s;", dstColor);
    if (gUseUnpremul) {
        fsBuilder->codeAppend("dst.rgb = clamp(dst.rgb / dst.a, 0.0, 1.0);");
    }

    fsBuilder->codeAppendf("%s = %s.x * src * dst + %s.y * src + %s.z * dst + %s.w;",
                           outputColor, kUni, kUni, kUni, kUni);
    fsBuilder->codeAppendf("%s = clamp(%s, 0.0, 1.0);\n", outputColor, outputColor);
    if (gUseUnpremul) {
        fsBuilder->codeAppendf("%s.rgb *= %s.a;", outputColor, outputColor);
    } else if (enforcePMColor) {
        fsBuilder->codeAppendf("%s.rgb = min(%s.rgb, %s.a);",
                               outputColor, outputColor, outputColor);
    }
}

class GLArithmeticFP : public GrGLFragmentProcessor {
public:
    GLArithmeticFP(const GrProcessor&)
        : fEnforcePMColor(true) {
    }

    ~GLArithmeticFP() override {}

    void emitCode(GrGLFPBuilder* builder,
                  const GrFragmentProcessor& fp,
                  const char* outputColor,
                  const char* inputColor,
                  const TransformedCoordsArray& coords,
                  const TextureSamplerArray& samplers) override {
        GrGLFPFragmentBuilder* fsBuilder = builder->getFragmentShaderBuilder();
        fsBuilder->codeAppend("vec4 bgColor = ");
        fsBuilder->appendTextureLookup(samplers[0], coords[0].c_str(), coords[0].getType());
        fsBuilder->codeAppendf(";");
        const char* dstColor = "bgColor";

        fKUni = builder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                    kVec4f_GrSLType, kDefault_GrSLPrecision,
                                    "k");
        const char* kUni = builder->getUniformCStr(fKUni);

        add_arithmetic_code(fsBuilder, inputColor, dstColor, outputColor, kUni, fEnforcePMColor);
    }

    void setData(const GrGLProgramDataManager& pdman, const GrProcessor& proc) override {
        const GrArithmeticFP& arith = proc.cast<GrArithmeticFP>();
        pdman.set4f(fKUni, arith.k1(), arith.k2(), arith.k3(), arith.k4());
        fEnforcePMColor = arith.enforcePMColor();
    }

    static void GenKey(const GrProcessor& proc, const GrGLCaps& caps, GrProcessorKeyBuilder* b) {
        const GrArithmeticFP& arith = proc.cast<GrArithmeticFP>();
        uint32_t key = arith.enforcePMColor() ? 1 : 0;
        b->add32(key);
    }

private:
    GrGLProgramDataManager::UniformHandle fKUni;
    bool fEnforcePMColor;

    typedef GrGLFragmentProcessor INHERITED;
};

///////////////////////////////////////////////////////////////////////////////

GrArithmeticFP::GrArithmeticFP(float k1, float k2, float k3, float k4,
                               bool enforcePMColor, GrTexture* background)
  : fK1(k1), fK2(k2), fK3(k3), fK4(k4), fEnforcePMColor(enforcePMColor) {
    this->initClassID<GrArithmeticFP>();

    SkASSERT(background);

    fBackgroundTransform.reset(kLocal_GrCoordSet, background,
                               GrTextureParams::kNone_FilterMode);
    this->addCoordTransform(&fBackgroundTransform);
    fBackgroundAccess.reset(background);
    this->addTextureAccess(&fBackgroundAccess);
}

void GrArithmeticFP::getGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const {
    GLArithmeticFP::GenKey(*this, caps, b);
}

GrGLFragmentProcessor* GrArithmeticFP::createGLInstance() const {
    return SkNEW_ARGS(GLArithmeticFP, (*this));
}

bool GrArithmeticFP::onIsEqual(const GrFragmentProcessor& fpBase) const {
    const GrArithmeticFP& fp = fpBase.cast<GrArithmeticFP>();
    return fK1 == fp.fK1 &&
           fK2 == fp.fK2 &&
           fK3 == fp.fK3 &&
           fK4 == fp.fK4 &&
           fEnforcePMColor == fp.fEnforcePMColor;
}

void GrArithmeticFP::onComputeInvariantOutput(GrInvariantOutput* inout) const {
    // TODO: optimize this
    inout->setToUnknown(GrInvariantOutput::kWill_ReadInput);
}

///////////////////////////////////////////////////////////////////////////////

GrFragmentProcessor* GrArithmeticFP::TestCreate(SkRandom* rand,
                                                GrContext*,
                                                const GrDrawTargetCaps&,
                                                GrTexture* textures[]) {
    float k1 = rand->nextF();
    float k2 = rand->nextF();
    float k3 = rand->nextF();
    float k4 = rand->nextF();
    bool enforcePMColor = rand->nextBool();

    return SkNEW_ARGS(GrArithmeticFP, (k1, k2, k3, k4, enforcePMColor, textures[0]));
}

GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrArithmeticFP);

///////////////////////////////////////////////////////////////////////////////
// Xfer Processor
///////////////////////////////////////////////////////////////////////////////

class ArithmeticXP : public GrXferProcessor {
public:
    static GrXferProcessor* Create(float k1, float k2, float k3, float k4, bool enforcePMColor,
                                   const GrDeviceCoordTexture* dstCopy,
                                   bool willReadDstColor) {
        return SkNEW_ARGS(ArithmeticXP, (k1, k2, k3, k4, enforcePMColor, dstCopy,
                                         willReadDstColor));
    }

    ~ArithmeticXP() override {};

    const char* name() const override { return "Arithmetic"; }

    GrGLXferProcessor* createGLInstance() const override;

    bool hasSecondaryOutput() const override { return false; }

    GrXferProcessor::OptFlags getOptimizations(const GrProcOptInfo& colorPOI,
                                               const GrProcOptInfo& coveragePOI,
                                               bool doesStencilWrite,
                                               GrColor* overrideColor,
                                               const GrDrawTargetCaps& caps) override;

    float k1() const { return fK1; }
    float k2() const { return fK2; }
    float k3() const { return fK3; }
    float k4() const { return fK4; }
    bool enforcePMColor() const { return fEnforcePMColor; }

private:
    ArithmeticXP(float k1, float k2, float k3, float k4, bool enforcePMColor,
                   const GrDeviceCoordTexture* dstCopy, bool willReadDstColor);

    void onGetGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const override;

    bool onIsEqual(const GrXferProcessor& xpBase) const override {
        const ArithmeticXP& xp = xpBase.cast<ArithmeticXP>();
        if (fK1 != xp.fK1 ||
            fK2 != xp.fK2 ||
            fK3 != xp.fK3 ||
            fK4 != xp.fK4 ||
            fEnforcePMColor != xp.fEnforcePMColor) {
            return false;
        }
        return true;
    }

    float                       fK1, fK2, fK3, fK4;
    bool                        fEnforcePMColor;

    typedef GrXferProcessor INHERITED;
};

///////////////////////////////////////////////////////////////////////////////

class GLArithmeticXP : public GrGLXferProcessor {
public:
    GLArithmeticXP(const GrProcessor&)
        : fEnforcePMColor(true) {
    }

    ~GLArithmeticXP() override {}

    static void GenKey(const GrProcessor& processor, const GrGLCaps& caps,
                       GrProcessorKeyBuilder* b) {
        const ArithmeticXP& arith = processor.cast<ArithmeticXP>();
        uint32_t key = arith.enforcePMColor() ? 1 : 0;
        b->add32(key);
    }

private:
    void onEmitCode(const EmitArgs& args) override {
        GrGLFPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();

        const char* dstColor = fsBuilder->dstColor();

        fKUni = args.fPB->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                     kVec4f_GrSLType, kDefault_GrSLPrecision,
                                     "k");
        const char* kUni = args.fPB->getUniformCStr(fKUni);

        add_arithmetic_code(fsBuilder, args.fInputColor, dstColor, args.fOutputPrimary, kUni, 
                            fEnforcePMColor);

        fsBuilder->codeAppendf("%s = %s * %s + (vec4(1.0) - %s) * %s;",
                               args.fOutputPrimary, args.fOutputPrimary, args.fInputCoverage,
                               args.fInputCoverage, dstColor);
    }

    void onSetData(const GrGLProgramDataManager& pdman,
                   const GrXferProcessor& processor) override {
        const ArithmeticXP& arith = processor.cast<ArithmeticXP>();
        pdman.set4f(fKUni, arith.k1(), arith.k2(), arith.k3(), arith.k4());
        fEnforcePMColor = arith.enforcePMColor();
    };

    GrGLProgramDataManager::UniformHandle fKUni;
    bool fEnforcePMColor;

    typedef GrGLXferProcessor INHERITED;
};

///////////////////////////////////////////////////////////////////////////////

ArithmeticXP::ArithmeticXP(float k1, float k2, float k3, float k4, bool enforcePMColor,
                           const GrDeviceCoordTexture* dstCopy, bool willReadDstColor)
    : INHERITED(dstCopy, willReadDstColor)
    , fK1(k1)
    , fK2(k2)
    , fK3(k3)
    , fK4(k4)
    , fEnforcePMColor(enforcePMColor) {
    this->initClassID<ArithmeticXP>();
}

void ArithmeticXP::onGetGLProcessorKey(const GrGLCaps& caps, GrProcessorKeyBuilder* b) const {
    GLArithmeticXP::GenKey(*this, caps, b);
}

GrGLXferProcessor* ArithmeticXP::createGLInstance() const {
    return SkNEW_ARGS(GLArithmeticXP, (*this));
}

GrXferProcessor::OptFlags ArithmeticXP::getOptimizations(const GrProcOptInfo& colorPOI,
                                                         const GrProcOptInfo& coveragePOI,
                                                         bool doesStencilWrite,
                                                         GrColor* overrideColor,
                                                         const GrDrawTargetCaps& caps) {
   return GrXferProcessor::kNone_Opt;
}

///////////////////////////////////////////////////////////////////////////////

GrArithmeticXPFactory::GrArithmeticXPFactory(float k1, float k2, float k3, float k4,
                                             bool enforcePMColor) 
    : fK1(k1), fK2(k2), fK3(k3), fK4(k4), fEnforcePMColor(enforcePMColor) {
    this->initClassID<GrArithmeticXPFactory>();
}

GrXferProcessor*
GrArithmeticXPFactory::onCreateXferProcessor(const GrDrawTargetCaps& caps,
                                             const GrProcOptInfo& colorPOI,
                                             const GrProcOptInfo& coveragePOI,
                                             const GrDeviceCoordTexture* dstCopy) const {
    return ArithmeticXP::Create(fK1, fK2, fK3, fK4, fEnforcePMColor, dstCopy,
                                this->willReadDstColor(caps, colorPOI, coveragePOI));
}


void GrArithmeticXPFactory::getInvariantOutput(const GrProcOptInfo& colorPOI,
                                               const GrProcOptInfo& coveragePOI,
                                               GrXPFactory::InvariantOutput* output) const {
    output->fWillBlendWithDst = true;

    // TODO: We could try to optimize this more. For example if we have solid coverage and fK1 and
    // fK3 are zero, then we won't be blending the color with dst at all so we can know what the
    // output color is (up to the valid color components passed in).
    output->fBlendedColorFlags = 0;
}

GR_DEFINE_XP_FACTORY_TEST(GrArithmeticXPFactory);

GrXPFactory* GrArithmeticXPFactory::TestCreate(SkRandom* random,
                                               GrContext*,
                                               const GrDrawTargetCaps&,
                                               GrTexture*[]) {
    float k1 = random->nextF();
    float k2 = random->nextF();
    float k3 = random->nextF();
    float k4 = random->nextF();
    bool enforcePMColor = random->nextBool();

    return GrArithmeticXPFactory::Create(k1, k2, k3, k4, enforcePMColor);
}

#endif