| /* |
| * Copyright 2014 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef GrFragmentProcessor_DEFINED |
| #define GrFragmentProcessor_DEFINED |
| |
| #include "GrProcessor.h" |
| |
| class GrCoordTransform; |
| class GrGLCaps; |
| class GrGLFragmentProcessor; |
| class GrProcessorKeyBuilder; |
| |
| /** Provides custom fragment shader code. Fragment processors receive an input color (vec4f) and |
| produce an output color. They may reference textures and uniforms. They may use |
| GrCoordTransforms to receive a transformation of the local coordinates that map from local space |
| to the fragment being processed. |
| */ |
| class GrFragmentProcessor : public GrProcessor { |
| public: |
| GrFragmentProcessor() |
| : INHERITED() |
| , fWillUseInputColor(true) |
| , fUsesLocalCoords(false) {} |
| |
| /** Implemented using GLFragmentProcessor::GenKey as described in this class's comment. */ |
| virtual void getGLProcessorKey(const GrGLCaps& caps, |
| GrProcessorKeyBuilder* b) const = 0; |
| |
| /** Returns a new instance of the appropriate *GL* implementation class |
| for the given GrFragmentProcessor; caller is responsible for deleting |
| the object. */ |
| virtual GrGLFragmentProcessor* createGLInstance() const = 0; |
| |
| /** Human-meaningful string to identify this GrFragmentProcessor; may be embedded |
| in generated shader code. */ |
| virtual const char* name() const = 0; |
| |
| int numTransforms() const { return fCoordTransforms.count(); } |
| |
| /** Returns the coordinate transformation at index. index must be valid according to |
| numTransforms(). */ |
| const GrCoordTransform& coordTransform(int index) const { return *fCoordTransforms[index]; } |
| |
| const SkTArray<const GrCoordTransform*, true>& coordTransforms() const { |
| return fCoordTransforms; |
| } |
| |
| /** Will this prceossor read the source color value? */ |
| bool willUseInputColor() const { return fWillUseInputColor; } |
| |
| /** Do any of the coordtransforms for this processor require local coords? */ |
| bool usesLocalCoords() const { return fUsesLocalCoords; } |
| |
| /** Returns true if this and other processor conservatively draw identically. It can only return |
| true when the two processor are of the same subclass (i.e. they return the same object from |
| from getFactory()). |
| |
| A return value of true from isEqual() should not be used to test whether the processor would |
| generate the same shader code. To test for identical code generation use getGLProcessorKey*/ |
| bool isEqual(const GrFragmentProcessor& that) const { |
| if (this->classID() != that.classID() || |
| !this->hasSameTransforms(that) || |
| !this->hasSameTextureAccesses(that)) { |
| return false; |
| } |
| return this->onIsEqual(that); |
| } |
| |
| /** |
| * This function is used to perform optimizations. When called the invarientOuput param |
| * indicate whether the input components to this processor in the FS will have known values. |
| * In inout the validFlags member is a bitfield of GrColorComponentFlags. The isSingleComponent |
| * member indicates whether the input will be 1 or 4 bytes. The function updates the members of |
| * inout to indicate known values of its output. A component of the color member only has |
| * meaning if the corresponding bit in validFlags is set. |
| */ |
| void computeInvariantOutput(GrInvariantOutput* inout) const; |
| |
| protected: |
| /** |
| * Fragment Processor subclasses call this from their constructor to register coordinate |
| * transformations. Coord transforms provide a mechanism for a processor to receive coordinates |
| * in their FS code. The matrix expresses a transformation from local space. For a given |
| * fragment the matrix will be applied to the local coordinate that maps to the fragment. |
| * |
| * When the transformation has perspective, the transformed coordinates will have |
| * 3 components. Otherwise they'll have 2. |
| * |
| * This must only be called from the constructor because GrProcessors are immutable. The |
| * processor subclass manages the lifetime of the transformations (this function only stores a |
| * pointer). The GrCoordTransform is typically a member field of the GrProcessor subclass. |
| * |
| * A processor subclass that has multiple methods of construction should always add its coord |
| * transforms in a consistent order. The non-virtual implementation of isEqual() automatically |
| * compares transforms and will assume they line up across the two processor instances. |
| */ |
| void addCoordTransform(const GrCoordTransform*); |
| |
| /** |
| * If the prceossor will generate a result that does not depend on the input color value then it |
| * must call this function from its constructor. Otherwise, when its generated backend-specific |
| * code might fail during variable binding due to unused variables. |
| */ |
| void setWillNotUseInputColor() { fWillUseInputColor = false; } |
| |
| /** |
| * Subclass implements this to support getConstantColorComponents(...). |
| */ |
| virtual void onComputeInvariantOutput(GrInvariantOutput* inout) const = 0; |
| |
| private: |
| /** |
| * Subclass implements this to support isEqual(). It will only be called if it is known that |
| * the two processors are of the same subclass (i.e. they return the same object from |
| * getFactory()). The processor subclass should not compare its coord transforms as that will |
| * be performed automatically in the non-virtual isEqual(). |
| */ |
| virtual bool onIsEqual(const GrFragmentProcessor&) const = 0; |
| |
| bool hasSameTransforms(const GrFragmentProcessor&) const; |
| |
| SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms; |
| bool fWillUseInputColor; |
| bool fUsesLocalCoords; |
| |
| typedef GrProcessor INHERITED; |
| }; |
| |
| #endif |