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* Copyright 2021 Google LLC.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef AtlasInstancedHelper_DEFINED
#define AtlasInstancedHelper_DEFINED
#include "src/core/SkIPoint16.h"
#include "src/gpu/ganesh/GrGeometryProcessor.h"
#include "src/gpu/ganesh/GrSurfaceProxyView.h"
#include "src/gpu/ganesh/glsl/GrGLSLUniformHandler.h"
namespace skgpu::v1 {
// This class encapsulates all the necessary steps for an instanced GrGeometryProcessor to clip
// against a path mask from an atlas.
class AtlasInstancedHelper {
enum class ShaderFlags {
kNone = 0,
kInvertCoverage = 1 << 0,
kCheckBounds = 1 << 1
constexpr static int kNumShaderFlags = 2;
AtlasInstancedHelper(GrSurfaceProxyView atlasView, ShaderFlags shaderFlags)
: fAtlasProxy(atlasView.detachProxy())
, fAtlasSwizzle(atlasView.swizzle())
, fShaderFlags(shaderFlags) {
// Bottom left origin is not supported.
SkASSERT(atlasView.origin() == kTopLeft_GrSurfaceOrigin);
GrSurfaceProxy* proxy() const { return fAtlasProxy.get(); }
const skgpu::Swizzle& atlasSwizzle() const { return fAtlasSwizzle; }
// Returns whether the two helpers can be batched together in a single draw.
bool isCompatible(const AtlasInstancedHelper& helper) {
// TODO: We may want to consider two helpers compatible if they only differ in the
// kCheckBounds flag -- we can always promote one to checking its bounds.
SkASSERT(fAtlasProxy != helper.fAtlasProxy || fAtlasSwizzle == helper.fAtlasSwizzle);
return fAtlasProxy == helper.fAtlasProxy && fShaderFlags == helper.fShaderFlags;
// Adds bits to the shader key that uniquely identify this specific helper's shader code.
void getKeyBits(KeyBuilder* b) const;
// Appends the instanced input attribs to the back of the array that we will need in order to
// locate our path in the atlas.
void appendInstanceAttribs(SkTArray<GrGeometryProcessor::Attribute>* instanceAttribs) const;
struct Instance {
Instance(SkIPoint16 locationInAtlas, const SkIRect& pathDevIBounds, bool transposedInAtlas)
: fLocationInAtlas(locationInAtlas)
, fPathDevIBounds(pathDevIBounds)
, fTransposedInAtlas(transposedInAtlas) {
SkASSERT(fLocationInAtlas.x() >= 0);
SkASSERT(fLocationInAtlas.y() >= 0);
SkIPoint16 fLocationInAtlas;
SkIRect fPathDevIBounds;
bool fTransposedInAtlas;
// Writes out the given instance data, formatted for the specific attribs that we added during
// appendInstanceAttribs().
void writeInstanceData(VertexWriter* instanceWriter, const Instance*) const;
// Injects vertex code, fragment code, varyings, and uniforms to ultimately multiply
// "args.fOutputCoverage" in the fragment shader by the atlas coverage.
// The caller is responsible to store "atlasAdjustUniformHandle" and pass it to
// setUniformData().
void injectShaderCode(const GrGeometryProcessor::ProgramImpl::EmitArgs&,
const GrShaderVar& devCoord,
GrGLSLUniformHandler::UniformHandle* atlasAdjustUniformHandle) const;
// The atlas clip requires one uniform value -- "atlasAdjustUniform". The caller should have
// stored this handle after its call to injectShaderCode(). This method sets its value prior to
// drawing.
void setUniformData(const GrGLSLProgramDataManager&,
const GrGLSLUniformHandler::UniformHandle& atlasAdjustUniformHandle) const;
const sk_sp<GrSurfaceProxy> fAtlasProxy;
const skgpu::Swizzle fAtlasSwizzle;
const ShaderFlags fShaderFlags;
} // namespace skgpu::v1
#endif // AtlasInstancedHelper_DEFINED