src/gpu/effects/GrDisableColorXP.cpp

/*
 * Copyright 2014 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "effects/GrDisableColorXP.h"
#include "GrProcessor.h"
#include "gl/GrGLXferProcessor.h"
#include "gl/builders/GrGLFragmentShaderBuilder.h"
#include "gl/builders/GrGLProgramBuilder.h"

class GrGLDisableColorXP : public GrGLXferProcessor {
public:
    GrGLDisableColorXP(const GrProcessor&) {}

    ~GrGLDisableColorXP() SK_OVERRIDE {}

    void emitCode(const EmitArgs& args) SK_OVERRIDE {
        // This emit code should be empty. However, on the nexus 6 there is a driver bug where if
        // you do not give gl_FragColor a value, the gl context is lost and we end up drawing
        // nothing. So this fix just sets the gl_FragColor arbitrarily to 0.
        GrGLFPFragmentBuilder* fsBuilder = args.fPB->getFragmentShaderBuilder();
        fsBuilder->codeAppendf("%s = vec4(0);", args.fOutputPrimary);
    }

    void setData(const GrGLProgramDataManager&, const GrXferProcessor&) SK_OVERRIDE {}

    static void GenKey(const GrProcessor&, const GrGLCaps&, GrProcessorKeyBuilder*) {}

private:
    typedef GrGLXferProcessor INHERITED;
};

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

GrDisableColorXP::GrDisableColorXP() {
    this->initClassID<GrDisableColorXP>();
}

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

GrGLXferProcessor* GrDisableColorXP::createGLInstance() const {
    return SkNEW_ARGS(GrGLDisableColorXP, (*this));
}

void GrDisableColorXP::getBlendInfo(GrXferProcessor::BlendInfo* blendInfo) const {
    blendInfo->fWriteColor = false;
}

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

GrDisableColorXPFactory::GrDisableColorXPFactory() {
    this->initClassID<GrDisableColorXPFactory>();
}

GrXferProcessor* GrDisableColorXPFactory::createXferProcessor(const GrProcOptInfo& colorPOI,
                                                              const GrProcOptInfo& covPOI) const {
    return GrDisableColorXP::Create();
}

GR_DEFINE_XP_FACTORY_TEST(GrDisableColorXPFactory);

GrXPFactory* GrDisableColorXPFactory::TestCreate(SkRandom* random,
                                                  GrContext*,
                                                  const GrDrawTargetCaps&,
                                                  GrTexture*[]) {
    return GrDisableColorXPFactory::Create();
}