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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrGLEffect_DEFINED
#define GrGLEffect_DEFINED
#include "GrBackendEffectFactory.h"
#include "GrGLProgramEffects.h"
#include "GrGLShaderVar.h"
#include "GrGLSL.h"
class GrGLShaderBuilder;
/** @file
This file contains specializations for OpenGL of the shader stages declared in
include/gpu/GrEffect.h. Objects of type GrGLEffect are responsible for emitting the
GLSL code that implements a GrEffect and for uploading uniforms at draw time. If they don't
always emit the same GLSL code, they must have a function:
static inline void GenKey(const GrDrawEffect&, const GrGLCaps&, GrEffectKeyBuilder*)
that is used to implement a program cache. When two GrEffects produce the same key this means
that their GrGLEffects would emit the same GLSL code.
The GrGLEffect subclass must also have a constructor of the form:
EffectSubclass::EffectSubclass(const GrBackendEffectFactory&, const GrDrawEffect&)
The effect held by the GrDrawEffect is guaranteed to be of the type that generated the
GrGLEffect subclass instance.
These objects are created by the factory object returned by the GrEffect::getFactory().
*/
class GrDrawEffect;
class GrGLTexture;
class GrGLVertexEffect;
class GrGLEffect {
public:
typedef GrGLProgramEffects::TransformedCoordsArray TransformedCoordsArray;
typedef GrGLProgramEffects::TextureSampler TextureSampler;
typedef GrGLProgramEffects::TextureSamplerArray TextureSamplerArray;
GrGLEffect(const GrBackendEffectFactory& factory)
: fFactory(factory)
, fIsVertexEffect(false) {
}
virtual ~GrGLEffect() {}
/** Called when the program stage should insert its code into the shaders. The code in each
shader will be in its own block ({}) and so locally scoped names will not collide across
stages.
@param builder Interface used to emit code in the shaders.
@param drawEffect A wrapper on the effect that generated this program stage.
@param key The key that was computed by GenKey() from the generating GrEffect.
@param outputColor A predefined vec4 in the FS in which the stage should place its output
color (or coverage).
@param inputColor A vec4 that holds the input color to the stage in the FS. This may be
NULL in which case the implied input is solid white (all ones).
TODO: Better system for communicating optimization info (e.g. input
color is solid white, trans black, known to be opaque, etc.) that allows
the effect to communicate back similar known info about its output.
@param samplers One entry for each GrTextureAccess of the GrEffect that generated the
GrGLEffect. These can be passed to the builder to emit texture
reads in the generated code.
*/
virtual void emitCode(GrGLProgramBuilder* builder,
const GrDrawEffect& drawEffect,
const GrEffectKey& key,
const char* outputColor,
const char* inputColor,
const TransformedCoordsArray& coords,
const TextureSamplerArray& samplers) = 0;
/** A GrGLEffect instance can be reused with any GrEffect that produces the same stage
key; this function reads data from a GrEffect and uploads any uniform variables required
by the shaders created in emitCode(). The GrEffect installed in the GrDrawEffect is
guaranteed to be of the same type that created this GrGLEffect and to have an identical
effect key as the one that created this GrGLEffect. Effects that use local coords have
to consider whether the GrEffectStage's coord change matrix should be used. When explicit
local coordinates are used it can be ignored. */
virtual void setData(const GrGLProgramDataManager&, const GrDrawEffect&) {}
const char* name() const { return fFactory.name(); }
static void GenKey(const GrDrawEffect&, const GrGLCaps&, GrEffectKeyBuilder*) {}
/** Used by the system when generating shader code, to see if this effect can be downcasted to
the internal GrGLVertexEffect type */
bool isVertexEffect() const { return fIsVertexEffect; }
protected:
const GrBackendEffectFactory& fFactory;
private:
friend class GrGLVertexEffect; // to set fIsVertexEffect
bool fIsVertexEffect;
};
#endif
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