1 /* 2 * Copyright 2012 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef GrGLEffect_DEFINED 9 #define GrGLEffect_DEFINED 10 11 #include "GrBackendEffectFactory.h" 12 #include "GrGLShaderBuilder.h" 13 #include "GrGLShaderVar.h" 14 #include "GrGLSL.h" 15 #include "GrEffectStage.h" 16 17 class GrGLTexture; 18 19 /** @file 20 This file contains specializations for OpenGL of the shader stages declared in 21 include/gpu/GrEffect.h. Objects of type GrGLEffect are responsible for emitting the 22 GLSL code that implements a GrEffect and for uploading uniforms at draw time. They also 23 must have a function: 24 static inline EffectKey GenKey(const GrEffectStage&, const GrGLCaps&) 25 that is used to implement a program cache. When two GrEffects produce the same key this means 26 that their GrGLEffects would emit the same GLSL code. 27 28 These objects are created by the factory object returned by the GrEffect::getFactory(). 29 */ 30 31 class GrGLEffect { 32 33 public: 34 typedef GrBackendEffectFactory::EffectKey EffectKey; 35 36 enum { 37 kNoEffectKey = GrBackendEffectFactory::kNoEffectKey, 38 // the number of bits in EffectKey available to GenKey 39 kEffectKeyBits = GrBackendEffectFactory::kEffectKeyBits, 40 }; 41 42 typedef GrGLShaderBuilder::TextureSamplerArray TextureSamplerArray; 43 44 GrGLEffect(const GrBackendEffectFactory&); 45 46 virtual ~GrGLEffect(); 47 48 /** Called when the program stage should insert its code into the shaders. The code in each 49 shader will be in its own block ({}) and so locally scoped names will not collide across 50 stages. 51 52 @param builder Interface used to emit code in the shaders. 53 @param stage The effect stage that generated this program stage. 54 @param key The key that was computed by GenKey() from the generating GrEffect. 55 Only the bits indicated by GrBackendEffectFactory::kEffectKeyBits are 56 guaranteed to match the value produced by GenKey(); 57 @param vertexCoords A vec2 in the VS that holds the position in local coords. This is either 58 the pre-view-matrix vertex position or if explicit per-vertex texture 59 coords are used with a stage then it is those coordinates. See 60 GrVertexLayout. 61 @param outputColor A predefined vec4 in the FS in which the stage should place its output 62 color (or coverage). 63 @param inputColor A vec4 that holds the input color to the stage in the FS. This may be 64 NULL in which case the implied input is solid white (all ones). 65 TODO: Better system for communicating optimization info (e.g. input 66 color is solid white, trans black, known to be opaque, etc.) that allows 67 the effect to communicate back similar known info about its output. 68 @param samplers One entry for each GrTextureAccess of the GrEffect that generated the 69 GrGLEffect. These can be passed to the builder to emit texture 70 reads in the generated code. 71 */ 72 virtual void emitCode(GrGLShaderBuilder* builder, 73 const GrEffectStage& stage, 74 EffectKey key, 75 const char* vertexCoords, 76 const char* outputColor, 77 const char* inputColor, 78 const TextureSamplerArray& samplers) = 0; 79 80 /** A GrGLEffect instance can be reused with any GrEffect that produces the same stage 81 key; this function reads data from a stage and uploads any uniform variables required 82 by the shaders created in emitCode(). The GrEffect installed in the GrEffectStage is 83 guaranteed to be of the same type that created this GrGLEffect and to have an identical 84 EffectKey as the one that created this GrGLEffect. */ 85 virtual void setData(const GrGLUniformManager&, const GrEffectStage&); 86 87 const char* name() const { return fFactory.name(); } 88 89 static EffectKey GenTextureKey(const GrEffectRef*, const GrGLCaps&); 90 91 /** 92 * GrGLEffect subclasses get passed a GrEffectStage in their emitCode and setData functions. 93 * The GrGLEffect usually needs to cast the stage's effect to the GrEffect subclass that 94 * generated the GrGLEffect. This helper does just that. 95 */ 96 template <typename T> 97 static const T& GetEffectFromStage(const GrEffectStage& effectStage) { 98 GrAssert(NULL != effectStage.getEffect()); 99 return CastEffect<T>(*effectStage.getEffect()); 100 } 101 102 /** 103 * Extracts the GrEffect from a GrEffectRef and down-casts to a GrEffect subclass. Usually used 104 * in a GrGLEffect subclass's constructor (which takes const GrEffectRef&). 105 */ 106 template <typename T> 107 static const T& CastEffect(const GrEffectRef& effectRef) { 108 GrAssert(NULL != effectRef.get()); 109 return *static_cast<const T*>(effectRef.get()); 110 } 111 112 protected: 113 const GrBackendEffectFactory& fFactory; 114 }; 115 116 #endif 117
