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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 GrGLSLFragmentProcessor_DEFINED
#define GrGLSLFragmentProcessor_DEFINED
#include "src/gpu/GrFragmentProcessor.h"
#include "src/gpu/GrShaderVar.h"
#include "src/gpu/glsl/GrGLSLPrimitiveProcessor.h"
#include "src/gpu/glsl/GrGLSLProgramDataManager.h"
#include "src/gpu/glsl/GrGLSLUniformHandler.h"
#include "src/sksl/SkSLString.h"
class GrProcessor;
class GrProcessorKeyBuilder;
class GrGLSLFPBuilder;
class GrGLSLFPFragmentBuilder;
class GrGLSLFragmentProcessor {
GrGLSLFragmentProcessor() {}
virtual ~GrGLSLFragmentProcessor() {
for (int i = 0; i < fChildProcessors.count(); ++i) {
delete fChildProcessors[i];
using UniformHandle = GrGLSLUniformHandler::UniformHandle;
using SamplerHandle = GrGLSLUniformHandler::SamplerHandle;
* This class allows the shader builder to provide each GrGLSLFragmentProcesor with an array of
* generated variables where each generated variable corresponds to an element of an array on
* the GrFragmentProcessor that generated the GLSLFP. For example, this is used to provide a
* variable holding transformed coords for each GrCoordTransform owned by the FP.
template <typename T, int (GrFragmentProcessor::*COUNT)() const>
class BuilderInputProvider {
BuilderInputProvider(const GrFragmentProcessor* fp, const T* ts) : fFP(fp) , fTs(ts) {}
const T& operator[] (int i) const {
SkASSERT(i >= 0 && i < (fFP->*COUNT)());
return fTs[i];
int count() const { return (fFP->*COUNT)(); }
BuilderInputProvider childInputs(int childIdx) const {
const GrFragmentProcessor* child = &fFP->childProcessor(childIdx);
GrFragmentProcessor::Iter iter(fFP);
int numToSkip = 0;
while (true) {
const GrFragmentProcessor* fp =;
if (fp == child) {
return BuilderInputProvider(child, fTs + numToSkip);
numToSkip += (fp->*COUNT)();
const GrFragmentProcessor* fFP;
const T* fTs;
using TransformedCoordVars = BuilderInputProvider<GrGLSLPrimitiveProcessor::TransformVar,
using TextureSamplers =
BuilderInputProvider<SamplerHandle, &GrFragmentProcessor::numTextureSamplers>;
/** Called when the program stage should insert its code into the shaders. The code in each
shader will be in its own block ({}) and so locally scoped names will not collide across
@param fragBuilder Interface used to emit code in the shaders.
@param fp The processor that generated this program stage.
@param key The key that was computed by GenKey() from the generating
@param outputColor A predefined half4 in the FS in which the stage should place its
output color (or coverage).
@param inputColor A half4 that holds the input color to the stage in the FS. This may
be nullptr in which case the fInputColor is set to "half4(1.0)"
(solid white) so this is guaranteed non-null.
TODO: Better system for communicating optimization info
(e.g. input color is solid white, trans black, known to be opaque,
etc.) that allows the processor to communicate back similar known
info about its output.
@param transformedCoords Fragment shader variables containing the coords computed using
each of the GrFragmentProcessor's GrCoordTransforms.
@param texSamplers Contains one entry for each TextureSampler of the GrProcessor.
These can be passed to the builder to emit texture reads in the
generated code.
struct EmitArgs {
EmitArgs(GrGLSLFPFragmentBuilder* fragBuilder,
GrGLSLUniformHandler* uniformHandler,
const GrShaderCaps* caps,
const GrFragmentProcessor& fp,
const char* outputColor,
const char* inputColor,
const TransformedCoordVars& transformedCoordVars,
const TextureSamplers& textureSamplers)
: fFragBuilder(fragBuilder)
, fUniformHandler(uniformHandler)
, fShaderCaps(caps)
, fFp(fp)
, fOutputColor(outputColor)
, fInputColor(inputColor ? inputColor : "half4(1.0)")
, fTransformedCoords(transformedCoordVars)
, fTexSamplers(textureSamplers) {}
GrGLSLFPFragmentBuilder* fFragBuilder;
GrGLSLUniformHandler* fUniformHandler;
const GrShaderCaps* fShaderCaps;
const GrFragmentProcessor& fFp;
const char* fOutputColor;
const char* fInputColor;
const TransformedCoordVars& fTransformedCoords;
const TextureSamplers& fTexSamplers;
virtual void emitCode(EmitArgs&) = 0;
// This does not recurse to any attached child processors. Recursing the entire processor tree
// is the responsibility of the caller.
void setData(const GrGLSLProgramDataManager& pdman, const GrFragmentProcessor& processor);
int numChildProcessors() const { return fChildProcessors.count(); }
GrGLSLFragmentProcessor* childProcessor(int index) {
return fChildProcessors[index];
// Invoke the child with the default input color (solid white)
inline void invokeChild(int childIndex, SkString* outputColor, EmitArgs& parentArgs,
SkSL::String skslCoords = "") {
this->invokeChild(childIndex, nullptr, outputColor, parentArgs, skslCoords);
/** Invokes a child proc in its own scope. Pass in the parent's EmitArgs and invokeChild will
* automatically extract the coords and samplers of that child and pass them on to the child's
* emitCode(). Also, any uniforms or functions emitted by the child will have their names
* mangled to prevent redefinitions. The output color name is also mangled therefore in an
* in/out param. It will be declared in mangled form by invokeChild(). It is legal to pass
* nullptr as inputColor, since all fragment processors are required to work without an input
* color.
void invokeChild(int childIndex, const char* inputColor, SkString* outputColor,
EmitArgs& parentArgs, SkSL::String skslCoords = "");
// Use the parent's output color to hold child's output, and use the
// default input color of solid white
inline void invokeChild(int childIndex, EmitArgs& args, SkSL::String skslCoords = "") {
// null pointer cast required to disambiguate the function call
this->invokeChild(childIndex, (const char*) nullptr, args, skslCoords);
/** Variation that uses the parent's output color variable to hold the child's output.*/
void invokeChild(int childIndex, const char* inputColor, EmitArgs& parentArgs,
SkSL::String skslCoords = "");
* Pre-order traversal of a GLSLFP hierarchy, or of multiple trees with roots in an array of
* GLSLFPS. This agrees with the traversal order of GrFragmentProcessor::Iter
class Iter : public SkNoncopyable {
explicit Iter(GrGLSLFragmentProcessor* fp) { fFPStack.push_back(fp); }
explicit Iter(std::unique_ptr<GrGLSLFragmentProcessor> fps[], int cnt) {
for (int i = cnt - 1; i >= 0; --i) {
GrGLSLFragmentProcessor* next();
SkSTArray<4, GrGLSLFragmentProcessor*, true> fFPStack;
/** A GrGLSLFragmentProcessor instance can be reused with any GrFragmentProcessor that produces
the same stage key; this function reads data from a GrFragmentProcessor and uploads any
uniform variables required by the shaders created in emitCode(). The GrFragmentProcessor
parameter is guaranteed to be of the same type that created this GrGLSLFragmentProcessor and
to have an identical processor key as the one that created this GrGLSLFragmentProcessor. */
virtual void onSetData(const GrGLSLProgramDataManager&, const GrFragmentProcessor&) {}
void writeChildCall(GrGLSLFPFragmentBuilder* fragBuilder, int childIndex,
TransformedCoordVars coordVars, const char* inputColor,
const char* outputColor, EmitArgs& args,
SkSL::String skslCoords);
void internalInvokeChild(int, const char*, const char*, EmitArgs&, SkSL::String);
// one per child; either not present or empty string if not yet emitted
SkTArray<SkString> fFunctionNames;
SkTArray<GrGLSLFragmentProcessor*, true> fChildProcessors;
friend class GrFragmentProcessor;