| /* |
| * 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 GrXferProcessor_DEFINED |
| #define GrXferProcessor_DEFINED |
| |
| #include "GrBlend.h" |
| #include "GrColor.h" |
| #include "GrProcessor.h" |
| #include "GrTexture.h" |
| #include "GrTypes.h" |
| #include "SkXfermode.h" |
| |
| class GrShaderCaps; |
| class GrGLSLCaps; |
| class GrGLSLXferProcessor; |
| class GrProcOptInfo; |
| struct GrPipelineOptimizations; |
| |
| /** |
| * Barriers for blending. When a shader reads the dst directly, an Xfer barrier is sometimes |
| * required after a pixel has been written, before it can be safely read again. |
| */ |
| enum GrXferBarrierType { |
| kNone_GrXferBarrierType = 0, //<! No barrier is required |
| kTexture_GrXferBarrierType, //<! Required when a shader reads and renders to the same texture. |
| kBlend_GrXferBarrierType, //<! Required by certain blend extensions. |
| }; |
| /** Should be able to treat kNone as false in boolean expressions */ |
| GR_STATIC_ASSERT(SkToBool(kNone_GrXferBarrierType) == false); |
| |
| /** |
| * GrXferProcessor is responsible for implementing the xfer mode that blends the src color and dst |
| * color, and for applying any coverage. It does this by emitting fragment shader code and |
| * controlling the fixed-function blend state. When dual-source blending is available, it may also |
| * write a seconday fragment shader output color. GrXferProcessor has two modes of operation: |
| * |
| * Dst read: When allowed by the backend API, or when supplied a texture of the destination, the |
| * GrXferProcessor may read the destination color. While operating in this mode, the subclass only |
| * provides shader code that blends the src and dst colors, and the base class applies coverage. |
| * |
| * No dst read: When not performing a dst read, the subclass is given full control of the fixed- |
| * function blend state and/or secondary output, and is responsible to apply coverage on its own. |
| * |
| * A GrXferProcessor is never installed directly into our draw state, but instead is created from a |
| * GrXPFactory once we have finalized the state of our draw. |
| */ |
| class GrXferProcessor : public GrProcessor { |
| public: |
| /** |
| * A texture that contains the dst pixel values and an integer coord offset from device space |
| * to the space of the texture. Depending on GPU capabilities a DstTexture may be used by a |
| * GrXferProcessor for blending in the fragment shader. |
| */ |
| class DstTexture { |
| public: |
| DstTexture() { fOffset.set(0, 0); } |
| |
| DstTexture(const DstTexture& other) { |
| *this = other; |
| } |
| |
| DstTexture(GrTexture* texture, const SkIPoint& offset) |
| : fTexture(SkSafeRef(texture)) |
| , fOffset(offset) { |
| } |
| |
| DstTexture& operator=(const DstTexture& other) { |
| fTexture.reset(SkSafeRef(other.fTexture.get())); |
| fOffset = other.fOffset; |
| return *this; |
| } |
| |
| const SkIPoint& offset() const { return fOffset; } |
| |
| void setOffset(const SkIPoint& offset) { fOffset = offset; } |
| void setOffset(int ox, int oy) { fOffset.set(ox, oy); } |
| |
| GrTexture* texture() const { return fTexture.get(); } |
| |
| GrTexture* setTexture(GrTexture* texture) { |
| fTexture.reset(SkSafeRef(texture)); |
| return texture; |
| } |
| |
| private: |
| SkAutoTUnref<GrTexture> fTexture; |
| SkIPoint fOffset; |
| }; |
| |
| /** |
| * Sets a unique key on the GrProcessorKeyBuilder calls onGetGLSLProcessorKey(...) to get the |
| * specific subclass's key. |
| */ |
| void getGLSLProcessorKey(const GrGLSLCaps& caps, GrProcessorKeyBuilder* b) const; |
| |
| /** Returns a new instance of the appropriate *GL* implementation class |
| for the given GrXferProcessor; caller is responsible for deleting |
| the object. */ |
| virtual GrGLSLXferProcessor* createGLSLInstance() const = 0; |
| |
| /** |
| * Optimizations for blending / coverage that an OptDrawState should apply to itself. |
| */ |
| enum OptFlags { |
| /** |
| * The draw can be skipped completely. |
| */ |
| kSkipDraw_OptFlag = 0x1, |
| /** |
| * GrXferProcessor will ignore color, thus no need to provide |
| */ |
| kIgnoreColor_OptFlag = 0x2, |
| /** |
| * GrXferProcessor will ignore coverage, thus no need to provide |
| */ |
| kIgnoreCoverage_OptFlag = 0x4, |
| /** |
| * Clear color stages and override input color to that returned by getOptimizations |
| */ |
| kOverrideColor_OptFlag = 0x8, |
| /** |
| * Can tweak alpha for coverage. Currently this flag should only be used by a batch |
| */ |
| kCanTweakAlphaForCoverage_OptFlag = 0x20, |
| }; |
| |
| static const OptFlags kNone_OptFlags = (OptFlags)0; |
| |
| GR_DECL_BITFIELD_OPS_FRIENDS(OptFlags); |
| |
| /** |
| * Determines which optimizations (as described by the ptFlags above) can be performed by |
| * the draw with this xfer processor. If this function is called, the xfer processor may change |
| * its state to reflected the given blend optimizations. If the XP needs to see a specific input |
| * color to blend correctly, it will set the OverrideColor flag and the output parameter |
| * overrideColor will be the required value that should be passed into the XP. |
| * A caller who calls this function on a XP is required to honor the returned OptFlags |
| * and color values for its draw. |
| */ |
| OptFlags getOptimizations(const GrPipelineOptimizations& optimizations, |
| bool doesStencilWrite, |
| GrColor* overrideColor, |
| const GrCaps& caps) const; |
| |
| /** |
| * Returns whether this XP will require an Xfer barrier on the given rt. If true, outBarrierType |
| * is updated to contain the type of barrier needed. |
| */ |
| GrXferBarrierType xferBarrierType(const GrRenderTarget* rt, const GrCaps& caps) const; |
| |
| struct BlendInfo { |
| void reset() { |
| fEquation = kAdd_GrBlendEquation; |
| fSrcBlend = kOne_GrBlendCoeff; |
| fDstBlend = kZero_GrBlendCoeff; |
| fBlendConstant = 0; |
| fWriteColor = true; |
| } |
| |
| SkDEBUGCODE(SkString dump() const;) |
| |
| GrBlendEquation fEquation; |
| GrBlendCoeff fSrcBlend; |
| GrBlendCoeff fDstBlend; |
| GrColor fBlendConstant; |
| bool fWriteColor; |
| }; |
| |
| void getBlendInfo(BlendInfo* blendInfo) const; |
| |
| bool willReadDstColor() const { return fWillReadDstColor; } |
| |
| /** |
| * Returns the texture to be used as the destination when reading the dst in the fragment |
| * shader. If the returned texture is NULL then the XP is either not reading the dst or we have |
| * extentions that support framebuffer fetching and thus don't need a copy of the dst texture. |
| */ |
| const GrTexture* getDstTexture() const { return fDstTexture.getTexture(); } |
| |
| /** |
| * Returns the offset in device coords to use when accessing the dst texture to get the dst |
| * pixel color in the shader. This value is only valid if getDstTexture() != NULL. |
| */ |
| const SkIPoint& dstTextureOffset() const { |
| SkASSERT(this->getDstTexture()); |
| return fDstTextureOffset; |
| } |
| |
| /** |
| * If we are performing a dst read, returns whether the base class will use mixed samples to |
| * antialias the shader's final output. If not doing a dst read, the subclass is responsible |
| * for antialiasing and this returns false. |
| */ |
| bool dstReadUsesMixedSamples() const { return fDstReadUsesMixedSamples; } |
| |
| /** |
| * Returns whether or not this xferProcossor will set a secondary output to be used with dual |
| * source blending. |
| */ |
| bool hasSecondaryOutput() const; |
| |
| /** 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 getGLSLProcessorKey |
| */ |
| |
| bool isEqual(const GrXferProcessor& that) const { |
| if (this->classID() != that.classID()) { |
| return false; |
| } |
| if (this->fWillReadDstColor != that.fWillReadDstColor) { |
| return false; |
| } |
| if (this->fDstTexture.getTexture() != that.fDstTexture.getTexture()) { |
| return false; |
| } |
| if (this->fDstTextureOffset != that.fDstTextureOffset) { |
| return false; |
| } |
| if (this->fDstReadUsesMixedSamples != that.fDstReadUsesMixedSamples) { |
| return false; |
| } |
| return this->onIsEqual(that); |
| } |
| |
| protected: |
| GrXferProcessor(); |
| GrXferProcessor(const DstTexture*, bool willReadDstColor, bool hasMixedSamples); |
| |
| private: |
| void notifyRefCntIsZero() const final {} |
| |
| virtual OptFlags onGetOptimizations(const GrPipelineOptimizations& optimizations, |
| bool doesStencilWrite, |
| GrColor* overrideColor, |
| const GrCaps& caps) const = 0; |
| |
| /** |
| * Sets a unique key on the GrProcessorKeyBuilder that is directly associated with this xfer |
| * processor's GL backend implementation. |
| */ |
| virtual void onGetGLSLProcessorKey(const GrGLSLCaps& caps, |
| GrProcessorKeyBuilder* b) const = 0; |
| |
| /** |
| * Determines the type of barrier (if any) required by the subclass. Note that the possibility |
| * that a kTexture type barrier is required is handled by the base class and need not be |
| * considered by subclass overrides of this function. |
| */ |
| virtual GrXferBarrierType onXferBarrier(const GrRenderTarget*, const GrCaps&) const { |
| return kNone_GrXferBarrierType; |
| } |
| |
| /** |
| * If we are not performing a dst read, returns whether the subclass will set a secondary |
| * output. When using dst reads, the base class controls the secondary output and this method |
| * will not be called. |
| */ |
| virtual bool onHasSecondaryOutput() const { return false; } |
| |
| /** |
| * If we are not performing a dst read, retrieves the fixed-function blend state required by the |
| * subclass. When using dst reads, the base class controls the fixed-function blend state and |
| * this method will not be called. The BlendInfo struct comes initialized to "no blending". |
| */ |
| virtual void onGetBlendInfo(BlendInfo*) const {} |
| |
| virtual bool onIsEqual(const GrXferProcessor&) const = 0; |
| |
| bool fWillReadDstColor; |
| bool fDstReadUsesMixedSamples; |
| SkIPoint fDstTextureOffset; |
| GrTextureAccess fDstTexture; |
| |
| typedef GrFragmentProcessor INHERITED; |
| }; |
| |
| GR_MAKE_BITFIELD_OPS(GrXferProcessor::OptFlags); |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| /** |
| * We install a GrXPFactory (XPF) early on in the pipeline before all the final draw information is |
| * known (e.g. whether there is fractional pixel coverage, will coverage be 1 or 4 channel, is the |
| * draw opaque, etc.). Once the state of the draw is finalized, we use the XPF along with all the |
| * draw information to create a GrXferProcessor (XP) which can implement the desired blending for |
| * the draw. |
| * |
| * Before the XP is created, the XPF is able to answer queries about what functionality the XPs it |
| * creates will have. For example, can it create an XP that supports RGB coverage or will the XP |
| * blend with the destination color. |
| */ |
| class GrXPFactory : public SkRefCnt { |
| public: |
| typedef GrXferProcessor::DstTexture DstTexture; |
| GrXferProcessor* createXferProcessor(const GrPipelineOptimizations& optimizations, |
| bool hasMixedSamples, |
| const DstTexture*, |
| const GrCaps& caps) const; |
| /** |
| * Known color information after blending, but before accounting for any coverage. |
| */ |
| struct InvariantBlendedColor { |
| bool fWillBlendWithDst; |
| GrColor fKnownColor; |
| GrColorComponentFlags fKnownColorFlags; |
| }; |
| |
| /** |
| * Returns information about the output color, produced by XPs from this factory, that will be |
| * known after blending. Note that we can conflate coverage and color, so the actual values |
| * written to pixels with partial coverage may not always seem consistent with the invariant |
| * information returned by this function. |
| */ |
| virtual void getInvariantBlendedColor(const GrProcOptInfo& colorPOI, |
| InvariantBlendedColor*) const = 0; |
| |
| bool willNeedDstTexture(const GrCaps& caps, const GrPipelineOptimizations& optimizations, |
| bool hasMixedSamples) const; |
| |
| bool isEqual(const GrXPFactory& that) const { |
| if (this->classID() != that.classID()) { |
| return false; |
| } |
| return this->onIsEqual(that); |
| } |
| |
| /** |
| * Helper for down-casting to a GrXPFactory subclass |
| */ |
| template <typename T> const T& cast() const { return *static_cast<const T*>(this); } |
| |
| uint32_t classID() const { SkASSERT(kIllegalXPFClassID != fClassID); return fClassID; } |
| |
| protected: |
| GrXPFactory() : fClassID(kIllegalXPFClassID) {} |
| |
| template <typename XPF_SUBCLASS> void initClassID() { |
| static uint32_t kClassID = GenClassID(); |
| fClassID = kClassID; |
| } |
| |
| uint32_t fClassID; |
| |
| private: |
| virtual GrXferProcessor* onCreateXferProcessor(const GrCaps& caps, |
| const GrPipelineOptimizations& optimizations, |
| bool hasMixedSamples, |
| const DstTexture*) const = 0; |
| |
| virtual bool onIsEqual(const GrXPFactory&) const = 0; |
| |
| bool willReadDstColor(const GrCaps& caps, |
| const GrPipelineOptimizations& optimizations, |
| bool hasMixedSamples) const; |
| /** |
| * Returns true if the XP generated by this factory will explicitly read dst in the fragment |
| * shader. |
| */ |
| virtual bool onWillReadDstColor(const GrCaps& caps, |
| const GrPipelineOptimizations& optimizations, |
| bool hasMixedSamples) const = 0; |
| |
| static uint32_t GenClassID() { |
| // fCurrXPFactoryID has been initialized to kIllegalXPFactoryID. The |
| // atomic inc returns the old value not the incremented value. So we add |
| // 1 to the returned value. |
| uint32_t id = static_cast<uint32_t>(sk_atomic_inc(&gCurrXPFClassID)) + 1; |
| if (!id) { |
| SkFAIL("This should never wrap as it should only be called once for each GrXPFactory " |
| "subclass."); |
| } |
| return id; |
| } |
| |
| enum { |
| kIllegalXPFClassID = 0, |
| }; |
| static int32_t gCurrXPFClassID; |
| |
| typedef GrProgramElement INHERITED; |
| }; |
| |
| #endif |
| |