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