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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkGaussianEdgeShader.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
/** \class SkGaussianEdgeShaderImpl
This subclass of shader applies a Gaussian to shadow edge
The radius of the Gaussian blur is specified by the g value of the color, in 6.2 fixed point.
For spot shadows, we increase the stroke width to set the shadow against the shape. This pad
is specified by b, also in 6.2 fixed point. The r value represents the max final alpha.
The incoming alpha should be 1.
*/
class SkGaussianEdgeShaderImpl : public SkShader {
public:
SkGaussianEdgeShaderImpl() {}
bool isOpaque() const override;
#if SK_SUPPORT_GPU
sk_sp<GrFragmentProcessor> asFragmentProcessor(const AsFPArgs&) const override;
#endif
SK_TO_STRING_OVERRIDE()
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkGaussianEdgeShaderImpl)
protected:
void flatten(SkWriteBuffer&) const override;
private:
friend class SkGaussianEdgeShader;
typedef SkShader INHERITED;
};
////////////////////////////////////////////////////////////////////////////
#if SK_SUPPORT_GPU
#include "GrCoordTransform.h"
#include "GrFragmentProcessor.h"
#include "GrInvariantOutput.h"
#include "glsl/GrGLSLFragmentProcessor.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "glsl/GrGLSLProgramDataManager.h"
#include "glsl/GrGLSLUniformHandler.h"
#include "SkGr.h"
#include "SkGrPriv.h"
class GaussianEdgeFP : public GrFragmentProcessor {
public:
GaussianEdgeFP() {
this->initClassID<GaussianEdgeFP>();
// enable output of distance information for shape
fUsesDistanceVectorField = true;
}
class GLSLGaussianEdgeFP : public GrGLSLFragmentProcessor {
public:
GLSLGaussianEdgeFP() {}
void emitCode(EmitArgs& args) override {
GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
fragBuilder->codeAppendf("vec4 color = %s;", args.fInputColor);
fragBuilder->codeAppend("float radius = color.g*64.0;");
fragBuilder->codeAppend("float pad = color.b*64.0;");
fragBuilder->codeAppendf("float factor = 1.0 - clamp((%s.z - pad)/radius, 0.0, 1.0);",
fragBuilder->distanceVectorName());
fragBuilder->codeAppend("factor = exp(-factor * factor * 4.0) - 0.018;");
fragBuilder->codeAppendf("%s = factor*vec4(0.0, 0.0, 0.0, color.r);", args.fOutputColor);
}
static void GenKey(const GrProcessor& proc, const GrGLSLCaps&,
GrProcessorKeyBuilder* b) {
// only one shader generated currently
b->add32(0x0);
}
protected:
void onSetData(const GrGLSLProgramDataManager& pdman, const GrProcessor& proc) override {}
};
void onGetGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const override {
GLSLGaussianEdgeFP::GenKey(*this, caps, b);
}
const char* name() const override { return "GaussianEdgeFP"; }
void onComputeInvariantOutput(GrInvariantOutput* inout) const override {
inout->mulByUnknownFourComponents();
}
private:
GrGLSLFragmentProcessor* onCreateGLSLInstance() const override { return new GLSLGaussianEdgeFP; }
bool onIsEqual(const GrFragmentProcessor& proc) const override { return true; }
};
////////////////////////////////////////////////////////////////////////////
sk_sp<GrFragmentProcessor> SkGaussianEdgeShaderImpl::asFragmentProcessor(const AsFPArgs& args) const {
return sk_make_sp<GaussianEdgeFP>();
}
#endif
////////////////////////////////////////////////////////////////////////////
bool SkGaussianEdgeShaderImpl::isOpaque() const {
return false;
}
////////////////////////////////////////////////////////////////////////////
#ifndef SK_IGNORE_TO_STRING
void SkGaussianEdgeShaderImpl::toString(SkString* str) const {
str->appendf("GaussianEdgeShader: ()");
}
#endif
sk_sp<SkFlattenable> SkGaussianEdgeShaderImpl::CreateProc(SkReadBuffer& buf) {
return sk_make_sp<SkGaussianEdgeShaderImpl>();
}
void SkGaussianEdgeShaderImpl::flatten(SkWriteBuffer& buf) const {
this->INHERITED::flatten(buf);
}
///////////////////////////////////////////////////////////////////////////////
sk_sp<SkShader> SkGaussianEdgeShader::Make() {
return sk_make_sp<SkGaussianEdgeShaderImpl>();
}
///////////////////////////////////////////////////////////////////////////////
SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkGaussianEdgeShader)
SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkGaussianEdgeShaderImpl)
SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
///////////////////////////////////////////////////////////////////////////////
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