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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 GrShaderCaps_DEFINED
#define GrShaderCaps_DEFINED
#include "GrSwizzle.h"
#include "GrTypesPriv.h"
#include "SkRefCnt.h"
#include "glsl/GrGLSL.h"
namespace SkSL {
class ShaderCapsFactory;
struct GrContextOptions;
class SkJSONWriter;
class GrShaderCaps : public SkRefCnt {
* Indicates how GLSL must interact with advanced blend equations. The KHR extension requires
* special layout qualifiers in the fragment shader.
enum AdvBlendEqInteraction {
kNotSupported_AdvBlendEqInteraction, //<! No _blend_equation_advanced extension
kAutomatic_AdvBlendEqInteraction, //<! No interaction required
kGeneralEnable_AdvBlendEqInteraction, //<! layout(blend_support_all_equations) out
kSpecificEnables_AdvBlendEqInteraction, //<! Specific layout qualifiers per equation
kLast_AdvBlendEqInteraction = kSpecificEnables_AdvBlendEqInteraction
GrShaderCaps(const GrContextOptions&);
void dumpJSON(SkJSONWriter*) const;
bool supportsDistanceFieldText() const { return fShaderDerivativeSupport; }
bool shaderDerivativeSupport() const { return fShaderDerivativeSupport; }
bool geometryShaderSupport() const { return fGeometryShaderSupport; }
bool gsInvocationsSupport() const { return fGSInvocationsSupport; }
bool pathRenderingSupport() const { return fPathRenderingSupport; }
bool dstReadInShaderSupport() const { return fDstReadInShaderSupport; }
bool dualSourceBlendingSupport() const { return fDualSourceBlendingSupport; }
bool integerSupport() const { return fIntegerSupport; }
bool texelBufferSupport() const { return fTexelBufferSupport; }
int imageLoadStoreSupport() const { return fImageLoadStoreSupport; }
* Some helper functions for encapsulating various extensions to read FB Buffer on openglES
* TODO(joshualitt) On desktop opengl 4.2+ we can achieve something similar to this effect
bool fbFetchSupport() const { return fFBFetchSupport; }
bool fbFetchNeedsCustomOutput() const { return fFBFetchNeedsCustomOutput; }
const char* versionDeclString() const { return fVersionDeclString; }
const char* fbFetchColorName() const { return fFBFetchColorName; }
const char* fbFetchExtensionString() const { return fFBFetchExtensionString; }
bool dropsTileOnZeroDivide() const { return fDropsTileOnZeroDivide; }
bool flatInterpolationSupport() const { return fFlatInterpolationSupport; }
bool preferFlatInterpolation() const { return fPreferFlatInterpolation; }
bool noperspectiveInterpolationSupport() const { return fNoPerspectiveInterpolationSupport; }
bool externalTextureSupport() const { return fExternalTextureSupport; }
bool texelFetchSupport() const { return fTexelFetchSupport; }
bool vertexIDSupport() const { return fVertexIDSupport; }
// frexp, ldexp, etc.
bool fpManipulationSupport() const { return fFPManipulationSupport; }
bool floatIs32Bits() const { return fFloatIs32Bits; }
bool halfIs32Bits() const { return fHalfIs32Bits; }
AdvBlendEqInteraction advBlendEqInteraction() const { return fAdvBlendEqInteraction; }
bool mustEnableAdvBlendEqs() const {
return fAdvBlendEqInteraction >= kGeneralEnable_AdvBlendEqInteraction;
bool mustEnableSpecificAdvBlendEqs() const {
return fAdvBlendEqInteraction == kSpecificEnables_AdvBlendEqInteraction;
bool mustDeclareFragmentShaderOutput() const { return fGLSLGeneration > k110_GrGLSLGeneration; }
bool usesPrecisionModifiers() const { return fUsesPrecisionModifiers; }
// Returns whether we can use the glsl function any() in our shader code.
bool canUseAnyFunctionInShader() const { return fCanUseAnyFunctionInShader; }
bool canUseMinAndAbsTogether() const { return fCanUseMinAndAbsTogether; }
bool canUseFractForNegativeValues() const { return fCanUseFractForNegativeValues; }
bool mustForceNegatedAtanParamToFloat() const { return fMustForceNegatedAtanParamToFloat; }
// Returns whether a device incorrectly implements atan(y,x) as atan(y/x)
bool atan2ImplementedAsAtanYOverX() const { return fAtan2ImplementedAsAtanYOverX; }
// If this returns true some operation (could be a no op) must be called between floor and abs
// to make sure the driver compiler doesn't inline them together which can cause a driver bug in
// the shader.
bool mustDoOpBetweenFloorAndAbs() const { return fMustDoOpBetweenFloorAndAbs; }
// If false, SkSL uses a workaround so that sk_FragCoord doesn't actually query gl_FragCoord
bool canUseFragCoord() const { return fCanUseFragCoord; }
// If true interpolated vertex shader outputs are inaccurate.
bool interpolantsAreInaccurate() const { return fInterpolantsAreInaccurate; }
// If true, short ints can't represent every integer in the 16-bit two's complement range as
// required by the spec. SKSL will always emit full ints.
bool incompleteShortIntPrecision() const { return fIncompleteShortIntPrecision; }
bool requiresLocalOutputColorForFBFetch() const { return fRequiresLocalOutputColorForFBFetch; }
bool mustObfuscateUniformColor() const { return fMustObfuscateUniformColor; }
// The D3D shader compiler, when targeting PS 3.0 (ie within ANGLE) fails to compile certain
// constructs. See detailed comments in GrGLCaps.cpp.
bool mustGuardDivisionEvenAfterExplicitZeroCheck() const {
return fMustGuardDivisionEvenAfterExplicitZeroCheck;
// Returns the string of an extension that must be enabled in the shader to support
// derivatives. If nullptr is returned then no extension needs to be enabled. Before calling
// this function, the caller should check that shaderDerivativeSupport exists.
const char* shaderDerivativeExtensionString() const {
return fShaderDerivativeExtensionString;
// Returns the string of an extension that must be enabled in the shader to support geometry
// shaders. If nullptr is returned then no extension needs to be enabled. Before calling this
// function, the caller must verify that geometryShaderSupport exists.
const char* geometryShaderExtensionString() const {
return fGeometryShaderExtensionString;
// Returns the string of an extension that must be enabled in the shader to support
// geometry shader invocations. If nullptr is returned then no extension needs to be enabled.
// Before calling this function, the caller must verify that gsInvocationsSupport exists.
const char* gsInvocationsExtensionString() const {
return fGSInvocationsExtensionString;
// Returns the string of an extension that will do all necessary coord transfomations needed
// when reading the fragment position. If such an extension does not exisits, this function
// returns a nullptr, and all transforms of the frag position must be done manually in the
// shader.
const char* fragCoordConventionsExtensionString() const {
return fFragCoordConventionsExtensionString;
// This returns the name of an extension that must be enabled in the shader, if such a thing is
// required in order to use a secondary output in the shader. This returns a nullptr if no such
// extension is required. However, the return value of this function does not say whether dual
// source blending is supported.
const char* secondaryOutputExtensionString() const { return fSecondaryOutputExtensionString; }
// This returns the name of an extension that must be enabled in the shader to support external
// textures. In some cases, two extensions must be enabled - the second extension is returned
// by secondExternalTextureExtensionString(). If that function returns nullptr, then only one
// extension is required.
const char* externalTextureExtensionString() const {
return fExternalTextureExtensionString;
const char* secondExternalTextureExtensionString() const {
return fSecondExternalTextureExtensionString;
const char* texelBufferExtensionString() const {
return fTexelBufferExtensionString;
const char* noperspectiveInterpolationExtensionString() const {
return fNoPerspectiveInterpolationExtensionString;
const char* imageLoadStoreExtensionString() const {
return fImageLoadStoreExtensionString;
int maxVertexSamplers() const { return fMaxVertexSamplers; }
int maxGeometrySamplers() const { return fMaxGeometrySamplers; }
int maxFragmentSamplers() const { return fMaxFragmentSamplers; }
int maxCombinedSamplers() const { return fMaxCombinedSamplers; }
* In general using multiple texture units for image rendering seems to be a win at smaller
* sizes of dst rects and a loss at larger sizes. Dst rects above this pixel area threshold will
* not use multitexturing.
size_t disableImageMultitexturingDstRectAreaThreshold() const {
return fDisableImageMultitexturingDstRectAreaThreshold;
* Given a texture's config, this determines what swizzle must be appended to accesses to the
* texture in generated shader code. Swizzling may be implemented in texture parameters or a
* sampler rather than in the shader. In this case the returned swizzle will always be "rgba".
const GrSwizzle& configTextureSwizzle(GrPixelConfig config) const {
return fConfigTextureSwizzle[config];
/** Swizzle that should occur on the fragment shader outputs for a given config. */
const GrSwizzle& configOutputSwizzle(GrPixelConfig config) const {
return fConfigOutputSwizzle[config];
GrGLSLGeneration generation() const { return fGLSLGeneration; }
void applyOptionsOverrides(const GrContextOptions& options);
GrGLSLGeneration fGLSLGeneration;
bool fShaderDerivativeSupport : 1;
bool fGeometryShaderSupport : 1;
bool fGSInvocationsSupport : 1;
bool fPathRenderingSupport : 1;
bool fDstReadInShaderSupport : 1;
bool fDualSourceBlendingSupport : 1;
bool fIntegerSupport : 1;
bool fTexelBufferSupport : 1;
bool fImageLoadStoreSupport : 1;
bool fDropsTileOnZeroDivide : 1;
bool fFBFetchSupport : 1;
bool fFBFetchNeedsCustomOutput : 1;
bool fUsesPrecisionModifiers : 1;
bool fFlatInterpolationSupport : 1;
bool fPreferFlatInterpolation : 1;
bool fNoPerspectiveInterpolationSupport : 1;
bool fExternalTextureSupport : 1;
bool fTexelFetchSupport : 1;
bool fVertexIDSupport : 1;
bool fFPManipulationSupport : 1;
bool fFloatIs32Bits : 1;
bool fHalfIs32Bits : 1;
// Used for specific driver bug work arounds
bool fCanUseAnyFunctionInShader : 1;
bool fCanUseMinAndAbsTogether : 1;
bool fCanUseFractForNegativeValues : 1;
bool fMustForceNegatedAtanParamToFloat : 1;
bool fAtan2ImplementedAsAtanYOverX : 1;
bool fMustDoOpBetweenFloorAndAbs : 1;
bool fRequiresLocalOutputColorForFBFetch : 1;
bool fMustObfuscateUniformColor : 1;
bool fMustGuardDivisionEvenAfterExplicitZeroCheck : 1;
bool fCanUseFragCoord : 1;
bool fInterpolantsAreInaccurate : 1;
bool fIncompleteShortIntPrecision : 1;
const char* fVersionDeclString;
const char* fShaderDerivativeExtensionString;
const char* fGeometryShaderExtensionString;
const char* fGSInvocationsExtensionString;
const char* fFragCoordConventionsExtensionString;
const char* fSecondaryOutputExtensionString;
const char* fExternalTextureExtensionString;
const char* fSecondExternalTextureExtensionString;
const char* fTexelBufferExtensionString;
const char* fNoPerspectiveInterpolationExtensionString;
const char* fImageLoadStoreExtensionString;
const char* fFBFetchColorName;
const char* fFBFetchExtensionString;
int fMaxVertexSamplers;
int fMaxGeometrySamplers;
int fMaxFragmentSamplers;
int fMaxCombinedSamplers;
size_t fDisableImageMultitexturingDstRectAreaThreshold;
AdvBlendEqInteraction fAdvBlendEqInteraction;
GrSwizzle fConfigTextureSwizzle[kGrPixelConfigCnt];
GrSwizzle fConfigOutputSwizzle[kGrPixelConfigCnt];
friend class GrCaps; // For initialization.
friend class GrGLCaps;
friend class GrMockCaps;
friend class GrMtlCaps;
friend class GrVkCaps;
friend class SkSL::ShaderCapsFactory;