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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrGeometryProcessor_DEFINED
#define GrGeometryProcessor_DEFINED
#include "GrPrimitiveProcessor.h"
/**
* A GrGeometryProcessor is a flexible method for rendering a primitive. The GrGeometryProcessor
* has complete control over vertex attributes and uniforms(aside from the render target) but it
* must obey the same contract as any GrPrimitiveProcessor, specifically it must emit a color and
* coverage into the fragment shader. Where this color and coverage come from is completely the
* responsibility of the GrGeometryProcessor.
*/
class GrGeometryProcessor : public GrPrimitiveProcessor {
public:
GrGeometryProcessor()
: fWillUseGeoShader(false)
, fLocalCoordsType(kUnused_LocalCoordsType)
, fSampleShading(0.0) {}
bool willUseGeoShader() const override { return fWillUseGeoShader; }
bool hasTransformedLocalCoords() const override {
return kHasTransformed_LocalCoordsType == fLocalCoordsType;
}
bool hasExplicitLocalCoords() const override {
return kHasExplicit_LocalCoordsType == fLocalCoordsType;
}
/**
* Returns the minimum fraction of samples for which the fragment shader will be run. For
* instance, if sampleShading is 0.5 in MSAA16 mode, the fragment shader will run a minimum of
* 8 times per pixel. The default value is zero.
*/
float getSampleShading() const override {
return fSampleShading;
}
protected:
/**
* Subclasses call this from their constructor to register vertex attributes. Attributes
* will be padded to the nearest 4 bytes for performance reasons.
* TODO After deferred geometry, we should do all of this inline in GenerateGeometry alongside
* the struct used to actually populate the attributes. This is all extremely fragile, vertex
* attributes have to be added in the order they will appear in the struct which maps memory.
* The processor key should reflect the vertex attributes, or there lack thereof in the
* GrGeometryProcessor.
*/
const Attribute& addVertexAttrib(const Attribute& attribute) {
fVertexStride += attribute.fOffset;
fAttribs.push_back(attribute);
return fAttribs.back();
}
void setWillUseGeoShader() { fWillUseGeoShader = true; }
/**
* If a GrFragmentProcessor in the GrPipeline needs localCoods, we will provide them in one of
* three ways
* 1) LocalCoordTransform * Position - in Shader
* 2) LocalCoordTransform * ExplicitLocalCoords- in Shader
* 3) A transformation on the CPU uploaded via vertex attribute
* TODO make this GrBatches responsibility
*/
enum LocalCoordsType {
kUnused_LocalCoordsType,
kHasExplicit_LocalCoordsType,
kHasTransformed_LocalCoordsType
};
void setHasExplicitLocalCoords() {
SkASSERT(kUnused_LocalCoordsType == fLocalCoordsType);
fLocalCoordsType = kHasExplicit_LocalCoordsType;
}
void setHasTransformedLocalCoords() {
SkASSERT(kUnused_LocalCoordsType == fLocalCoordsType);
fLocalCoordsType = kHasTransformed_LocalCoordsType;
}
void setSampleShading(float sampleShading) {
fSampleShading = sampleShading;
}
private:
bool fWillUseGeoShader;
LocalCoordsType fLocalCoordsType;
float fSampleShading;
typedef GrPrimitiveProcessor INHERITED;
};
#endif