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* Copyright 2013 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef GrGeometryProcessor_DEFINED
#define GrGeometryProcessor_DEFINED
#include "src/gpu/GrColor.h"
#include "src/gpu/GrFragmentProcessor.h"
#include "src/gpu/GrProcessor.h"
#include "src/gpu/GrShaderCaps.h"
#include "src/gpu/GrShaderVar.h"
#include "src/gpu/GrSwizzle.h"
#include "src/gpu/glsl/GrGLSLProgramDataManager.h"
#include "src/gpu/glsl/GrGLSLUniformHandler.h"
#include "src/gpu/glsl/GrGLSLVarying.h"
#include <unordered_map>
class GrGLSLFPFragmentBuilder;
class GrGLSLVaryingHandler;
class GrGLSLUniformHandler;
class GrGLSLVertexBuilder;
* The GrGeometryProcessor represents some kind of geometric primitive. This includes the shape
* of the primitive and the inherent color of the primitive. The GrGeometryProcessor is
* responsible for providing a color and coverage input into the Ganesh rendering pipeline. Through
* optimization, Ganesh may decide a different color, no color, and / or no coverage are required
* from the GrGeometryProcessor, so the GrGeometryProcessor must be able to support this
* functionality.
* There are two feedback loops between the GrFragmentProcessors, the GrXferProcessor, and the
* GrGeometryProcessor. These loops run on the CPU and to determine known properties of the final
* color and coverage inputs to the GrXferProcessor in order to perform optimizations that preserve
* correctness. The GrDrawOp seeds these loops with initial color and coverage, in its
* getProcessorAnalysisInputs implementation. These seed values are processed by the
* subsequent stages of the rendering pipeline and the output is then fed back into the GrDrawOp
* in the applyPipelineOptimizations call, where the op can use the information to inform
* decisions about GrGeometryProcessor creation.
* Note that all derived classes should hide their constructors and provide a Make factory
* function that takes an arena (except for Tesselation-specific classes). This is because
* geometry processors can be created in either the record-time or flush-time arenas which
* define their lifetimes (i.e., a DDLs life time in the first case and a single flush in
* the second case).
class GrGeometryProcessor : public GrProcessor {
* Every GrGeometryProcessor must be capable of creating a subclass of ProgramImpl. The
* ProgramImpl emits the shader code that implements the GrGeometryProcessor, is attached to the
* generated backend API pipeline/program and used to extract uniform data from
* GrGeometryProcessor instances.
class ProgramImpl;
class TextureSampler;
/** Describes a vertex or instance attribute. */
class Attribute {
constexpr Attribute() = default;
constexpr Attribute(const char* name,
GrVertexAttribType cpuType,
GrSLType gpuType)
: fName(name), fCPUType(cpuType), fGPUType(gpuType) {
SkASSERT(name && gpuType != kVoid_GrSLType);
constexpr Attribute(const Attribute&) = default;
Attribute& operator=(const Attribute&) = default;
constexpr bool isInitialized() const { return fGPUType != kVoid_GrSLType; }
constexpr const char* name() const { return fName; }
constexpr GrVertexAttribType cpuType() const { return fCPUType; }
constexpr GrSLType gpuType() const { return fGPUType; }
inline constexpr size_t size() const;
constexpr size_t sizeAlign4() const { return SkAlign4(this->size()); }
GrShaderVar asShaderVar() const {
return {fName, fGPUType, GrShaderVar::TypeModifier::In};
const char* fName = nullptr;
GrVertexAttribType fCPUType = kFloat_GrVertexAttribType;
GrSLType fGPUType = kVoid_GrSLType;
class Iter {
Iter() : fCurr(nullptr), fRemaining(0) {}
Iter(const Iter& iter) : fCurr(iter.fCurr), fRemaining(iter.fRemaining) {}
Iter& operator= (const Iter& iter) {
fCurr = iter.fCurr;
fRemaining = iter.fRemaining;
return *this;
Iter(const Attribute* attrs, int count) : fCurr(attrs), fRemaining(count) {
bool operator!=(const Iter& that) const { return fCurr != that.fCurr; }
const Attribute& operator*() const { return *fCurr; }
void operator++() {
if (fRemaining) {
void skipUninitialized() {
if (!fRemaining) {
fCurr = nullptr;
} else {
while (!fCurr->isInitialized()) {
const Attribute* fCurr;
int fRemaining;
class AttributeSet {
Iter begin() const { return Iter(fAttributes, fCount); }
Iter end() const { return Iter(); }
int count() const { return fCount; }
size_t stride() const { return fStride; }
friend class GrGeometryProcessor;
void init(const Attribute* attrs, int count) {
fAttributes = attrs;
fRawCount = count;
fCount = 0;
fStride = 0;
for (int i = 0; i < count; ++i) {
if (attrs[i].isInitialized()) {
fStride += attrs[i].sizeAlign4();
const Attribute* fAttributes = nullptr;
int fRawCount = 0;
int fCount = 0;
size_t fStride = 0;
int numTextureSamplers() const { return fTextureSamplerCnt; }
const TextureSampler& textureSampler(int index) const;
int numVertexAttributes() const { return fVertexAttributes.fCount; }
const AttributeSet& vertexAttributes() const { return fVertexAttributes; }
int numInstanceAttributes() const { return fInstanceAttributes.fCount; }
const AttributeSet& instanceAttributes() const { return fInstanceAttributes; }
bool hasVertexAttributes() const { return SkToBool(fVertexAttributes.fCount); }
bool hasInstanceAttributes() const { return SkToBool(fInstanceAttributes.fCount); }
* A common practice is to populate the the vertex/instance's memory using an implicit array of
* structs. In this case, it is best to assert that:
* stride == sizeof(struct)
size_t vertexStride() const { return fVertexAttributes.fStride; }
size_t instanceStride() const { return fInstanceAttributes.fStride; }
bool willUseTessellationShaders() const {
return fShaders & (kTessControl_GrShaderFlag | kTessEvaluation_GrShaderFlag);
* Computes a key for the transforms owned by an FP based on the shader code that will be
* emitted by the primitive processor to implement them.
static uint32_t ComputeCoordTransformsKey(const GrFragmentProcessor& fp);
static constexpr int kCoordTransformKeyBits = 4;
* Adds a key on the GrProcessorKeyBuilder that reflects any variety in the code that the
* geometry processor subclass can emit.
virtual void addToKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const = 0;
void getAttributeKey(GrProcessorKeyBuilder* b) const {
// Ensure that our CPU and GPU type fields fit together in a 32-bit value, and we never
// collide with the "uninitialized" value.
static_assert(kGrVertexAttribTypeCount < (1 << 8), "");
static_assert(kGrSLTypeCount < (1 << 8), "");
auto add_attributes = [=](const Attribute* attrs, int attrCount) {
for (int i = 0; i < attrCount; ++i) {
const Attribute& attr = attrs[i];
b->appendComment(attr.isInitialized() ? : "unusedAttr");
b->addBits(8, attr.isInitialized() ? attr.cpuType() : 0xff, "attrType");
b->addBits(8, attr.isInitialized() ? attr.gpuType() : 0xff, "attrGpuType");
b->add32(fVertexAttributes.fRawCount, "numVertexAttributes");
add_attributes(fVertexAttributes.fAttributes, fVertexAttributes.fRawCount);
b->add32(fInstanceAttributes.fRawCount, "numInstanceAttributes");
add_attributes(fInstanceAttributes.fAttributes, fInstanceAttributes.fRawCount);
* Returns a new instance of the appropriate implementation class for the given
* GrGeometryProcessor.
virtual std::unique_ptr<ProgramImpl> makeProgramImpl(const GrShaderCaps&) const = 0;
// GPs that need to use either float or ubyte colors can just call this to get a correctly
// configured Attribute struct
static Attribute MakeColorAttribute(const char* name, bool wideColor) {
return { name,
wideColor ? kFloat4_GrVertexAttribType : kUByte4_norm_GrVertexAttribType,
kHalf4_GrSLType };
void setVertexAttributes(const Attribute* attrs, int attrCount) {
fVertexAttributes.init(attrs, attrCount);
void setInstanceAttributes(const Attribute* attrs, int attrCount) {
SkASSERT(attrCount >= 0);
fInstanceAttributes.init(attrs, attrCount);
void setWillUseTessellationShaders() {
fShaders |= kTessControl_GrShaderFlag | kTessEvaluation_GrShaderFlag;
void setTextureSamplerCnt(int cnt) {
SkASSERT(cnt >= 0);
fTextureSamplerCnt = cnt;
* Helper for implementing onTextureSampler(). E.g.:
* return IthTexureSampler(i, fMyFirstSampler, fMySecondSampler, fMyThirdSampler);
template <typename... Args>
static const TextureSampler& IthTextureSampler(int i, const TextureSampler& samp0,
const Args&... samps) {
return (0 == i) ? samp0 : IthTextureSampler(i - 1, samps...);
inline static const TextureSampler& IthTextureSampler(int i);
virtual const TextureSampler& onTextureSampler(int) const { return IthTextureSampler(0); }
GrShaderFlags fShaders = kVertex_GrShaderFlag | kFragment_GrShaderFlag;
AttributeSet fVertexAttributes;
AttributeSet fInstanceAttributes;
int fTextureSamplerCnt = 0;
using INHERITED = GrProcessor;
class GrGeometryProcessor::ProgramImpl {
using UniformHandle = GrGLSLProgramDataManager::UniformHandle;
using SamplerHandle = GrGLSLUniformHandler::SamplerHandle;
* Struct of optional varying that replaces the input coords and bool indicating whether the FP
* should take a coord param as an argument. The latter may be false if the coords are simply
* unused or if the GP has lifted their computation to a varying emitted by the VS.
struct FPCoords {GrShaderVar coordsVarying; bool hasCoordsParam;};
using FPCoordsMap = std::unordered_map<const GrFragmentProcessor*, FPCoords>;
virtual ~ProgramImpl() = default;
struct EmitArgs {
EmitArgs(GrGLSLVertexBuilder* vertBuilder,
GrGLSLFPFragmentBuilder* fragBuilder,
GrGLSLVaryingHandler* varyingHandler,
GrGLSLUniformHandler* uniformHandler,
const GrShaderCaps* caps,
const GrGeometryProcessor& geomProc,
const char* outputColor,
const char* outputCoverage,
const SamplerHandle* texSamplers)
: fVertBuilder(vertBuilder)
, fFragBuilder(fragBuilder)
, fVaryingHandler(varyingHandler)
, fUniformHandler(uniformHandler)
, fShaderCaps(caps)
, fGeomProc(geomProc)
, fOutputColor(outputColor)
, fOutputCoverage(outputCoverage)
, fTexSamplers(texSamplers) {}
GrGLSLVertexBuilder* fVertBuilder;
GrGLSLFPFragmentBuilder* fFragBuilder;
GrGLSLVaryingHandler* fVaryingHandler;
GrGLSLUniformHandler* fUniformHandler;
const GrShaderCaps* fShaderCaps;
const GrGeometryProcessor& fGeomProc;
const char* fOutputColor;
const char* fOutputCoverage;
const SamplerHandle* fTexSamplers;
* Emits the code from this geometry processor into the shaders. For any FP in the pipeline that
* has its input coords implemented by the GP as a varying, the varying will be accessible in
* the returned map and should be used when the FP code is emitted.
FPCoordsMap emitCode(EmitArgs&, const GrPipeline& pipeline);
* Called after all effect emitCode() functions, to give the processor a chance to write out
* additional transformation code now that all uniforms have been emitted.
* It generates the final code for assigning transformed coordinates to the varyings recorded
* in the call to collectTransforms(). This must happen after FP code emission so that it has
* access to any uniforms the FPs registered for uniform sample matrix invocations.
void emitTransformCode(GrGLSLVertexBuilder* vb, GrGLSLUniformHandler* uniformHandler);
* A ProgramImpl instance can be reused with any GrGeometryProcessor that produces the same key.
* This function reads data from a GrGeometryProcessor and updates any uniform variables
* required by the shaders created in emitCode(). The GrGeometryProcessor parameter is
* guaranteed to be of the same type and to have an identical processor key as the
* GrGeometryProcessor that created this ProgramImpl.
virtual void setData(const GrGLSLProgramDataManager&,
const GrShaderCaps&,
const GrGeometryProcessor&) = 0;
// We use these methods as a temporary back door to inject OpenGL tessellation code. Once
// tessellation is supported by SkSL we can remove these.
virtual SkString getTessControlShaderGLSL(const GrGeometryProcessor&,
const char* versionAndExtensionDecls,
const GrGLSLUniformHandler&,
const GrShaderCaps&) const {
SK_ABORT("Not implemented.");
virtual SkString getTessEvaluationShaderGLSL(const GrGeometryProcessor&,
const char* versionAndExtensionDecls,
const GrGLSLUniformHandler&,
const GrShaderCaps&) const {
SK_ABORT("Not implemented.");
// GPs that use writeOutputPosition and/or writeLocalCoord must incorporate the matrix type
// into their key, and should use this function or one of the other related helpers.
static uint32_t ComputeMatrixKey(const GrShaderCaps& caps, const SkMatrix& mat) {
if (!caps.reducedShaderMode()) {
if (mat.isIdentity()) {
return 0b00;
if (mat.isScaleTranslate()) {
return 0b01;
if (!mat.hasPerspective()) {
return 0b10;
return 0b11;
static uint32_t ComputeMatrixKeys(const GrShaderCaps& shaderCaps,
const SkMatrix& viewMatrix,
const SkMatrix& localMatrix) {
return (ComputeMatrixKey(shaderCaps, viewMatrix) << kMatrixKeyBits) |
ComputeMatrixKey(shaderCaps, localMatrix);
static uint32_t AddMatrixKeys(const GrShaderCaps& shaderCaps,
uint32_t flags,
const SkMatrix& viewMatrix,
const SkMatrix& localMatrix) {
// Shifting to make room for the matrix keys shouldn't lose bits
SkASSERT(((flags << (2 * kMatrixKeyBits)) >> (2 * kMatrixKeyBits)) == flags);
return (flags << (2 * kMatrixKeyBits)) |
ComputeMatrixKeys(shaderCaps, viewMatrix, localMatrix);
static constexpr int kMatrixKeyBits = 2;
void setupUniformColor(GrGLSLFPFragmentBuilder* fragBuilder,
GrGLSLUniformHandler* uniformHandler,
const char* outputName,
UniformHandle* colorUniform);
// A helper for setting the matrix on a uniform handle initialized through
// writeOutputPosition or writeLocalCoord. Automatically handles elided uniforms,
// scale+translate matrices, and state tracking (if provided state pointer is non-null).
static void SetTransform(const GrGLSLProgramDataManager&,
const GrShaderCaps&,
const UniformHandle& uniform,
const SkMatrix& matrix,
SkMatrix* state = nullptr);
struct GrGPArgs {
// Used to specify the output variable used by the GP to store its device position. It can
// either be a float2 or a float3 (in order to handle perspective). The subclass sets this
// in its onEmitCode().
GrShaderVar fPositionVar;
// Used to specify the variable storing the draw's local coordinates. It can be either a
// float2, float3, or void. It can only be void when no FP needs local coordinates. This
// variable can be an attribute or local variable, but should not itself be a varying.
// ProgramImpl automatically determines if this must be passed to a FS.
GrShaderVar fLocalCoordVar;
// Helpers for adding code to write the transformed vertex position. The first simple version
// just writes a variable named by 'posName' into the position output variable with the
// assumption that the position is 2D. The second version transforms the input position by a
// view matrix and the output variable is 2D or 3D depending on whether the view matrix is
// perspective. Both versions declare the output position variable and will set
// GrGPArgs::fPositionVar.
static void WriteOutputPosition(GrGLSLVertexBuilder*, GrGPArgs*, const char* posName);
static void WriteOutputPosition(GrGLSLVertexBuilder*,
const GrShaderCaps&,
const char* posName,
const SkMatrix& viewMatrix,
UniformHandle* viewMatrixUniform);
// Helper to transform an existing variable by a given local matrix (e.g. the inverse view
// matrix). It will declare the transformed local coord variable and will set
// GrGPArgs::fLocalCoordVar.
static void WriteLocalCoord(GrGLSLVertexBuilder*,
const GrShaderCaps&,
GrShaderVar localVar,
const SkMatrix& localMatrix,
UniformHandle* localMatrixUniform);
virtual void onEmitCode(EmitArgs&, GrGPArgs*) = 0;
// Iterates over the FPs beginning with the passed iter to register additional varyings and
// uniforms to support VS-promoted local coord evaluation for the FPs.
// This must happen before FP code emission so that the FPs can find the appropriate varying
// handles they use in place of explicit coord sampling; it is automatically called after
// onEmitCode() returns using the value stored in GpArgs::fLocalCoordVar and
// GpArgs::fPositionVar.
FPCoordsMap collectTransforms(GrGLSLVertexBuilder* vb,
GrGLSLVaryingHandler* varyingHandler,
GrGLSLUniformHandler* uniformHandler,
const GrShaderVar& localCoordsVar,
const GrShaderVar& positionVar,
const GrPipeline& pipeline);
struct TransformInfo {
// The varying that conveys the coordinates to one or more FPs in the FS.
GrGLSLVarying varying;
// The coordinate to be transformed. varying is computed from this.
GrShaderVar inputCoords;
// Used to sort so that ancestor FP varyings are initialized before descendant FP varyings.
int traversalOrder;
// Populated by collectTransforms() for use in emitTransformCode(). When we lift the computation
// of a FP's input coord to a varying we propagate that varying up the FP tree to the highest
// node that shares the same coordinates. This allows multiple FPs in a subtree to share a
// varying.
std::unordered_map<const GrFragmentProcessor*, TransformInfo> fTransformVaryingsMap;
* Used to capture the properties of the GrTextureProxies required/expected by a primitiveProcessor
* along with an associated GrSamplerState. The actual proxies used are stored in either the
* fixed or dynamic state arrays. TextureSamplers don't perform any coord manipulation to account
* for texture origin.
class GrGeometryProcessor::TextureSampler {
TextureSampler() = default;
TextureSampler(GrSamplerState, const GrBackendFormat&, const GrSwizzle&);
TextureSampler(const TextureSampler&) = delete;
TextureSampler& operator=(const TextureSampler&) = delete;
void reset(GrSamplerState, const GrBackendFormat&, const GrSwizzle&);
const GrBackendFormat& backendFormat() const { return fBackendFormat; }
GrTextureType textureType() const { return fBackendFormat.textureType(); }
GrSamplerState samplerState() const { return fSamplerState; }
const GrSwizzle& swizzle() const { return fSwizzle; }
bool isInitialized() const { return fIsInitialized; }
GrSamplerState fSamplerState;
GrBackendFormat fBackendFormat;
GrSwizzle fSwizzle;
bool fIsInitialized = false;
const GrGeometryProcessor::TextureSampler& GrGeometryProcessor::IthTextureSampler(int i) {
SK_ABORT("Illegal texture sampler index");
static const TextureSampler kBogus;
return kBogus;
* Returns the size of the attrib type in bytes.
* This was moved from include/private/GrTypesPriv.h in service of Skia dependents that build
* with C++11.
static constexpr inline size_t GrVertexAttribTypeSize(GrVertexAttribType type) {
switch (type) {
case kFloat_GrVertexAttribType:
return sizeof(float);
case kFloat2_GrVertexAttribType:
return 2 * sizeof(float);
case kFloat3_GrVertexAttribType:
return 3 * sizeof(float);
case kFloat4_GrVertexAttribType:
return 4 * sizeof(float);
case kHalf_GrVertexAttribType:
return sizeof(uint16_t);
case kHalf2_GrVertexAttribType:
return 2 * sizeof(uint16_t);
case kHalf4_GrVertexAttribType:
return 4 * sizeof(uint16_t);
case kInt2_GrVertexAttribType:
return 2 * sizeof(int32_t);
case kInt3_GrVertexAttribType:
return 3 * sizeof(int32_t);
case kInt4_GrVertexAttribType:
return 4 * sizeof(int32_t);
case kByte_GrVertexAttribType:
return 1 * sizeof(char);
case kByte2_GrVertexAttribType:
return 2 * sizeof(char);
case kByte4_GrVertexAttribType:
return 4 * sizeof(char);
case kUByte_GrVertexAttribType:
return 1 * sizeof(char);
case kUByte2_GrVertexAttribType:
return 2 * sizeof(char);
case kUByte4_GrVertexAttribType:
return 4 * sizeof(char);
case kUByte_norm_GrVertexAttribType:
return 1 * sizeof(char);
case kUByte4_norm_GrVertexAttribType:
return 4 * sizeof(char);
case kShort2_GrVertexAttribType:
return 2 * sizeof(int16_t);
case kShort4_GrVertexAttribType:
return 4 * sizeof(int16_t);
case kUShort2_GrVertexAttribType: // fall through
case kUShort2_norm_GrVertexAttribType:
return 2 * sizeof(uint16_t);
case kInt_GrVertexAttribType:
return sizeof(int32_t);
case kUint_GrVertexAttribType:
return sizeof(uint32_t);
case kUShort_norm_GrVertexAttribType:
return sizeof(uint16_t);
case kUShort4_norm_GrVertexAttribType:
return 4 * sizeof(uint16_t);
// GCC fails because SK_ABORT evaluates to non constexpr. clang and cl.exe think this is
// unreachable and don't complain.
#if defined(__clang__) || !defined(__GNUC__)
SK_ABORT("Unsupported type conversion");
return 0;
constexpr size_t GrGeometryProcessor::Attribute::size() const {
return GrVertexAttribTypeSize(fCPUType);