blob: 5e8e4c396fbbe878661c8b8e53ea42108cad464a [file] [log] [blame]
/*
* Copyright 2024 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/gpu/graphite/ShaderInfo.h"
#include "src/gpu/BlendFormula.h"
#include "src/gpu/graphite/ContextUtils.h"
#include "src/gpu/graphite/PaintParamsKey.h"
#include "src/gpu/graphite/Renderer.h"
#include "src/gpu/graphite/ShaderCodeDictionary.h"
#include "src/gpu/graphite/UniformManager.h"
#include "src/sksl/SkSLString.h"
#include "src/sksl/SkSLUtil.h"
using namespace skia_private;
namespace skgpu::graphite {
namespace {
std::string get_uniform_header(int set, int bufferID, const char* name) {
std::string result;
SkSL::String::appendf(
&result, "layout (set=%d, binding=%d) uniform %sUniforms {\n", set, bufferID, name);
return result;
}
std::string get_uniforms(UniformOffsetCalculator* offsetter,
SkSpan<const Uniform> uniforms,
int manglingSuffix,
bool* wrotePaintColor) {
std::string result;
std::string uniformName;
for (const Uniform& u : uniforms) {
uniformName = u.name();
if (u.isPaintColor() && wrotePaintColor) {
if (*wrotePaintColor) {
SkSL::String::appendf(&result, " // deduplicated %s\n", u.name());
continue;
}
*wrotePaintColor = true;
} else {
if (manglingSuffix >= 0) {
uniformName.append("_");
uniformName.append(std::to_string(manglingSuffix));
}
}
SkSL::String::appendf(&result,
" layout(offset=%d) %s %s",
offsetter->advanceOffset(u.type(), u.count()),
SkSLTypeString(u.type()),
uniformName.c_str());
if (u.count()) {
result.append("[");
result.append(std::to_string(u.count()));
result.append("]");
}
result.append(";\n");
}
return result;
}
std::string get_node_uniforms(UniformOffsetCalculator* offsetter,
const ShaderNode* node,
bool* wrotePaintColor) {
std::string result;
SkSpan<const Uniform> uniforms = node->entry()->fUniforms;
if (!uniforms.empty()) {
if (node->entry()->fUniformStructName) {
auto substruct = UniformOffsetCalculator::ForStruct(offsetter->layout());
for (const Uniform& u : uniforms) {
substruct.advanceOffset(u.type(), u.count());
}
const int structOffset = offsetter->advanceStruct(substruct);
SkSL::String::appendf(&result,
"layout(offset=%d) %s node_%d;",
structOffset,
node->entry()->fUniformStructName,
node->keyIndex());
} else {
#if defined(SK_DEBUG)
SkSL::String::appendf(&result, "// %d - %s uniforms\n",
node->keyIndex(), node->entry()->fName);
#endif
result += get_uniforms(offsetter, uniforms, node->keyIndex(), wrotePaintColor);
}
}
for (const ShaderNode* child : node->children()) {
result += get_node_uniforms(offsetter, child, wrotePaintColor);
}
return result;
}
std::string get_ssbo_fields(SkSpan<const Uniform> uniforms,
int manglingSuffix,
bool* wrotePaintColor) {
std::string result;
std::string uniformName;
for (const Uniform& u : uniforms) {
uniformName = u.name();
if (u.isPaintColor() && wrotePaintColor) {
if (*wrotePaintColor) {
#if defined(SK_DEBUG)
SkSL::String::appendf(&result, " // deduplicated %s\n", u.name());
#endif
continue;
}
*wrotePaintColor = true;
} else {
if (manglingSuffix >= 0) {
uniformName.append("_");
uniformName.append(std::to_string(manglingSuffix));
}
}
SkSL::String::appendf(&result, " %s %s", SkSLTypeString(u.type()), uniformName.c_str());
if (u.count()) {
SkSL::String::appendf(&result, "[%d]", u.count());
}
result.append(";\n");
}
return result;
}
std::string get_node_ssbo_fields(const ShaderNode* node, bool* wrotePaintColor) {
std::string result;
SkSpan<const Uniform> uniforms = node->entry()->fUniforms;
if (!uniforms.empty()) {
if (node->entry()->fUniformStructName) {
SkSL::String::appendf(&result, "%s node_%d;",
node->entry()->fUniformStructName, node->keyIndex());
} else {
#if defined(SK_DEBUG)
SkSL::String::appendf(&result, "// %d - %s uniforms\n",
node->keyIndex(), node->entry()->fName);
#endif
result += get_ssbo_fields(uniforms, node->keyIndex(), wrotePaintColor);
}
}
for (const ShaderNode* child : node->children()) {
result += get_node_ssbo_fields(child, wrotePaintColor);
}
return result;
}
std::string emit_intrinsic_constants(const ResourceBindingRequirements& bindingReqs) {
std::string result;
auto offsetter = UniformOffsetCalculator::ForTopLevel(bindingReqs.fUniformBufferLayout);
if (bindingReqs.fUseVulkanPushConstantsForIntrinsicConstants) {
result = "layout (vulkan, push_constant) uniform IntrinsicUniforms {\n";
} else {
result = get_uniform_header(bindingReqs.fUniformsSetIdx,
bindingReqs.fIntrinsicBufferBinding,
"Intrinsic");
}
result += get_uniforms(&offsetter, kIntrinsicUniforms, -1, /* wrotePaintColor= */ nullptr);
result.append("};\n\n");
SkASSERTF(bindingReqs.fUseVulkanPushConstantsForIntrinsicConstants ||
result.find('[') == std::string::npos,
"Arrays are not supported in intrinsic uniforms");
return result;
}
std::string emit_paint_params_uniforms(int set,
int bufferID,
const Layout layout,
SkSpan<const ShaderNode*> nodes,
bool* hasUniforms,
bool* wrotePaintColor) {
auto offsetter = UniformOffsetCalculator::ForTopLevel(layout);
std::string result = get_uniform_header(set, bufferID, "FS");
for (const ShaderNode* n : nodes) {
result += get_node_uniforms(&offsetter, n, wrotePaintColor);
}
result.append("};\n\n");
*hasUniforms = offsetter.size() > 0;
if (!*hasUniforms) {
// No uniforms were added
return {};
}
return result;
}
std::string emit_render_step_uniforms(int set,
int bufferID,
const Layout layout,
SkSpan<const Uniform> uniforms) {
auto offsetter = UniformOffsetCalculator::ForTopLevel(layout);
std::string result = get_uniform_header(set, bufferID, "Step");
result += get_uniforms(&offsetter, uniforms, -1, /* wrotePaintColor= */ nullptr);
result.append("};\n\n");
return result;
}
std::string emit_paint_params_storage_buffer(int set,
int bufferID,
SkSpan<const ShaderNode*> nodes,
bool* hasUniforms,
bool* wrotePaintColor) {
*hasUniforms = false;
std::string fields;
for (const ShaderNode* n : nodes) {
fields += get_node_ssbo_fields(n, wrotePaintColor);
}
if (fields.empty()) {
// No uniforms were added
*hasUniforms = false;
return {};
}
*hasUniforms = true;
return SkSL::String::printf(
"struct FSUniformData {\n"
"%s\n"
"};\n\n"
"layout (set=%d, binding=%d) readonly buffer FSUniforms {\n"
"FSUniformData fsUniformData[];\n"
"};\n",
fields.c_str(),
set,
bufferID);
}
std::string emit_render_step_storage_buffer(int set, int bufferID, SkSpan<const Uniform> uniforms) {
SkASSERT(!uniforms.empty());
std::string fields = get_ssbo_fields(uniforms, -1, /*wrotePaintColor=*/nullptr);
return SkSL::String::printf(
"struct StepUniformData {\n"
"%s\n"
"};\n\n"
"layout (set=%d, binding=%d) readonly buffer StepUniforms {\n"
" StepUniformData stepUniformData[];\n"
"};\n",
fields.c_str(),
set,
bufferID);
}
std::string emit_uniforms_from_storage_buffer(const char* bufferNamePrefix,
const char* shadingSsboIndex,
SkSpan<const Uniform> uniforms) {
std::string result;
for (const Uniform& u : uniforms) {
SkSL::String::appendf(&result, "%s %s", SkSLTypeString(u.type()), u.name());
if (u.count()) {
SkSL::String::appendf(&result, "[%d]", u.count());
}
SkSL::String::appendf(&result,
" = %sUniformData[%s].%s;\n",
bufferNamePrefix,
shadingSsboIndex,
u.name());
}
return result;
}
void append_sampler_descs(const SkSpan<const uint32_t> samplerData,
skia_private::TArray<SamplerDesc>& outDescs) {
// Sampler data consists of variable-length SamplerDesc representations which can differ based
// upon a sampler's immutability and format. For this reason, handle incrementing i in the loop.
for (size_t i = 0; i < samplerData.size();) {
// Create a default-initialized SamplerDesc (which only takes up one uint32). If we are
// using a dynamic sampler, this will be directly inserted into outDescs. Otherwise, it will
// be populated with actual immutable sampler data and then inserted.
SamplerDesc desc{};
size_t samplerDescLength = 1;
SkASSERT(desc.asSpan().size() == samplerDescLength);
// Isolate the ImmutableSamplerInfo portion of the SamplerDesc represented by samplerData.
// If immutableSamplerInfo is non-zero, that means we are using an immutable sampler.
uint32_t immutableSamplerInfo = samplerData[i] >> SamplerDesc::kImmutableSamplerInfoShift;
if (immutableSamplerInfo != 0) {
// Consult the first bit of immutableSamplerInfo which tells us whether the sampler uses
// a known or external format. With this, update sampler description length.
bool usesExternalFormat = immutableSamplerInfo & 0b1;
samplerDescLength = usesExternalFormat ? SamplerDesc::kInt32sNeededExternalFormat
: SamplerDesc::kInt32sNeededKnownFormat;
// Populate a SamplerDesc with samplerDescLength quantity of immutable sampler data
memcpy(&desc, samplerData.begin() + i, samplerDescLength * sizeof(uint32_t));
}
outDescs.push_back(desc);
i += samplerDescLength;
}
}
std::string get_node_texture_samplers(const ResourceBindingRequirements& bindingReqs,
const ShaderNode* node,
int* binding,
skia_private::TArray<SamplerDesc>* outDescs) {
std::string result;
SkSpan<const TextureAndSampler> samplers = node->entry()->fTexturesAndSamplers;
if (!samplers.empty()) {
#if defined(SK_DEBUG)
SkSL::String::appendf(&result, "// %d - %s samplers\n",
node->keyIndex(), node->entry()->fName);
#endif
// Determine whether we need to analyze & interpret a ShaderNode's data as immutable
// SamplerDescs based upon whether:
// 1) A backend passes in a non-nullptr outImmutableSamplers param (may be nullptr in
// backends or circumstances where we know immutable sampler data is never stored)
// 2) Any data is stored on the ShaderNode
// 3) Whether the ShaderNode snippet's ID matches that of any snippet ID that could store
// immutable sampler data.
int32_t snippetId = node->codeSnippetId();
if (outDescs) {
// TODO(b/369846881): Refactor checking snippet ID to instead having a named
// snippet requirement flag that we can check here to decrease fragility.
if (!node->data().empty() &&
(snippetId == static_cast<int32_t>(BuiltInCodeSnippetID::kImageShader) ||
snippetId == static_cast<int32_t>(BuiltInCodeSnippetID::kImageShaderClamp) ||
snippetId == static_cast<int32_t>(BuiltInCodeSnippetID::kCubicImageShader) ||
snippetId == static_cast<int32_t>(BuiltInCodeSnippetID::kHWImageShader))) {
append_sampler_descs(node->data(), *outDescs);
} else {
// Add default SamplerDescs for any dynamic samplers to outDescs.
outDescs->push_back_n(samplers.size());
}
}
for (const TextureAndSampler& t : samplers) {
result += EmitSamplerLayout(bindingReqs, binding);
SkSL::String::appendf(&result, " sampler2D %s_%d;\n", t.name(), node->keyIndex());
}
}
for (const ShaderNode* child : node->children()) {
result += get_node_texture_samplers(bindingReqs, child, binding, outDescs);
}
return result;
}
std::string emit_textures_and_samplers(const ResourceBindingRequirements& bindingReqs,
SkSpan<const ShaderNode*> nodes,
int* binding,
skia_private::TArray<SamplerDesc>* outDescs) {
std::string result;
for (const ShaderNode* n : nodes) {
result += get_node_texture_samplers(bindingReqs, n, binding, outDescs);
}
return result;
}
std::string emit_varyings(const RenderStep* step,
const char* direction,
SkSpan<const ShaderNode*> liftedExpressions,
bool emitSsboIndicesVarying,
bool emitLocalCoordsVarying) {
std::string result;
int location = 0;
auto appendVarying = [&](const Varying& v) {
const char* interpolation;
switch (v.interpolation()) {
case Interpolation::kPerspective: interpolation = ""; break;
case Interpolation::kLinear: interpolation = "noperspective "; break;
case Interpolation::kFlat: interpolation = "flat "; break;
}
SkSL::String::appendf(&result, "layout(location=%d) %s %s%s %s;\n",
location++,
direction,
interpolation,
SkSLTypeString(v.gpuType()),
v.name());
};
if (emitSsboIndicesVarying) {
appendVarying({RenderStep::ssboIndicesVarying(), SkSLType::kUInt2});
}
if (emitLocalCoordsVarying) {
appendVarying({"localCoordsVar", SkSLType::kFloat2});
}
for (const ShaderNode* node : liftedExpressions) {
// TODO(b/402402925) Provide a way for lifted expressions to declare their varying type.
std::string name = node->getExpressionVarying();
appendVarying({name.c_str(), SkSLType::kFloat2});
}
for (auto v : step->varyings()) {
appendVarying(v);
}
return result;
}
// Walk the node tree and generate all preambles, accumulating into 'preamble'.
void emit_preambles(const ShaderInfo& shaderInfo,
SkSpan<const ShaderNode*> nodes,
std::string treeLabel,
std::string* preamble) {
for (int i = 0; i < SkTo<int>(nodes.size()); ++i) {
const ShaderNode* node = nodes[i];
std::string nodeLabel = std::to_string(i);
std::string nextLabel = treeLabel.empty() ? nodeLabel : (treeLabel + "<-" + nodeLabel);
if (node->numChildren() > 0) {
emit_preambles(shaderInfo, node->children(), nextLabel, preamble);
}
std::string nodePreamble = node->entry()->fPreambleGenerator
? node->entry()->fPreambleGenerator(shaderInfo, node)
: node->generateDefaultPreamble(shaderInfo);
if (!nodePreamble.empty()) {
SkSL::String::appendf(preamble,
"// [%d] %s: %s\n"
"%s\n",
node->keyIndex(),
nextLabel.c_str(),
node->entry()->fName,
nodePreamble.c_str());
}
}
}
std::string emit_color_output(BlendFormula::OutputType outputType,
const char* outColor,
const char* inColor) {
switch (outputType) {
case BlendFormula::kNone_OutputType:
return SkSL::String::printf("%s = half4(0.0);", outColor);
case BlendFormula::kCoverage_OutputType:
return SkSL::String::printf("%s = outputCoverage;", outColor);
case BlendFormula::kModulate_OutputType:
return SkSL::String::printf("%s = %s * outputCoverage;", outColor, inColor);
case BlendFormula::kSAModulate_OutputType:
return SkSL::String::printf("%s = %s.a * outputCoverage;", outColor, inColor);
case BlendFormula::kISAModulate_OutputType:
return SkSL::String::printf("%s = (1.0 - %s.a) * outputCoverage;", outColor, inColor);
case BlendFormula::kISCModulate_OutputType:
return SkSL::String::printf(
"%s = (half4(1.0) - %s) * outputCoverage;", outColor, inColor);
default:
SkUNREACHABLE;
}
}
void collect_lifted_expressions(SkSpan<const ShaderNode*> nodes,
std::vector<const ShaderNode*>& lifted) {
for (const ShaderNode* node : nodes) {
SkASSERT(!(node->requiredFlags() & SnippetRequirementFlags::kLiftExpression) ||
node->entry()->fLiftableExpressionGenerator);
if ((node->requiredFlags() & SnippetRequirementFlags::kLiftExpression) &&
node->entry()->fLiftableExpressionGenerator) {
lifted.push_back(node);
}
collect_lifted_expressions(node->children(), lifted);
}
};
constexpr skgpu::BlendInfo make_simple_blendInfo(skgpu::BlendCoeff srcCoeff,
skgpu::BlendCoeff dstCoeff) {
return { skgpu::BlendEquation::kAdd,
srcCoeff,
dstCoeff,
SK_PMColor4fTRANSPARENT,
skgpu::BlendModifiesDst(skgpu::BlendEquation::kAdd, srcCoeff, dstCoeff) };
}
static constexpr int kNumCoeffModes = (int)SkBlendMode::kLastCoeffMode + 1;
static constexpr skgpu::BlendInfo gBlendTable[kNumCoeffModes] = {
/* clear */ make_simple_blendInfo(skgpu::BlendCoeff::kZero, skgpu::BlendCoeff::kZero),
/* src */ make_simple_blendInfo(skgpu::BlendCoeff::kOne, skgpu::BlendCoeff::kZero),
/* dst */ make_simple_blendInfo(skgpu::BlendCoeff::kZero, skgpu::BlendCoeff::kOne),
/* src-over */ make_simple_blendInfo(skgpu::BlendCoeff::kOne, skgpu::BlendCoeff::kISA),
/* dst-over */ make_simple_blendInfo(skgpu::BlendCoeff::kIDA, skgpu::BlendCoeff::kOne),
/* src-in */ make_simple_blendInfo(skgpu::BlendCoeff::kDA, skgpu::BlendCoeff::kZero),
/* dst-in */ make_simple_blendInfo(skgpu::BlendCoeff::kZero, skgpu::BlendCoeff::kSA),
/* src-out */ make_simple_blendInfo(skgpu::BlendCoeff::kIDA, skgpu::BlendCoeff::kZero),
/* dst-out */ make_simple_blendInfo(skgpu::BlendCoeff::kZero, skgpu::BlendCoeff::kISA),
/* src-atop */ make_simple_blendInfo(skgpu::BlendCoeff::kDA, skgpu::BlendCoeff::kISA),
/* dst-atop */ make_simple_blendInfo(skgpu::BlendCoeff::kIDA, skgpu::BlendCoeff::kSA),
/* xor */ make_simple_blendInfo(skgpu::BlendCoeff::kIDA, skgpu::BlendCoeff::kISA),
/* plus */ make_simple_blendInfo(skgpu::BlendCoeff::kOne, skgpu::BlendCoeff::kOne),
/* modulate */ make_simple_blendInfo(skgpu::BlendCoeff::kZero, skgpu::BlendCoeff::kSC),
/* screen */ make_simple_blendInfo(skgpu::BlendCoeff::kOne, skgpu::BlendCoeff::kISC)
};
} // anonymous namespace
std::unique_ptr<ShaderInfo> ShaderInfo::Make(const Caps* caps,
const ShaderCodeDictionary* dict,
const RuntimeEffectDictionary* rteDict,
const RenderStep* step,
UniquePaintParamsID paintID,
bool useStorageBuffers,
skgpu::Swizzle writeSwizzle,
DstReadStrategy dstReadStrategy,
skia_private::TArray<SamplerDesc>* outDescs) {
const char* shadingSsboIndex =
useStorageBuffers && step->performsShading() ? "shadingSsboIndex" : nullptr;
// If paintID is not valid this is a depth-only draw and there's no fragment shader to compile.
const bool hasFragShader = paintID.isValid();
// Each ShaderInfo is responsible for determining whether or not a dst read is required. This
// generally occurs while generating the frag shader, but if we do not use one, then we know we
// do not need to read the dst texture and can assign the DstReadStrategy to kNoneRequired.
auto result = std::unique_ptr<ShaderInfo>(
new ShaderInfo(dict, rteDict,
shadingSsboIndex,
hasFragShader ? dstReadStrategy : DstReadStrategy::kNoneRequired));
// The fragment shader must be generated before the vertex shader, because we determine
// properties of the entire program while generating the fragment shader.
if (hasFragShader) {
result->generateFragmentSkSL(caps,
dict,
step,
paintID,
useStorageBuffers,
writeSwizzle,
outDescs);
}
result->generateVertexSkSL(caps,
step,
useStorageBuffers);
return result;
}
ShaderInfo::ShaderInfo(const ShaderCodeDictionary* shaderCodeDictionary,
const RuntimeEffectDictionary* rteDict,
const char* shadingSsboIndex,
DstReadStrategy dstReadStrategy)
: fShaderCodeDictionary(shaderCodeDictionary)
, fRuntimeEffectDictionary(rteDict)
, fShadingSsboIndex(shadingSsboIndex)
, fDstReadStrategy(dstReadStrategy) {}
namespace {
std::string dst_read_strategy_to_str(DstReadStrategy strategy) {
switch (strategy) {
case DstReadStrategy::kNoneRequired:
return "NoneRequired";
case DstReadStrategy::kTextureCopy:
return "TextureCopy";
case DstReadStrategy::kTextureSample:
return "TextureSample";
case DstReadStrategy::kReadFromInput:
return "ReadFromInput";
case DstReadStrategy::kFramebufferFetch:
return "FramebufferFetch";
default:
SkUNREACHABLE;
}
return "";
}
} // anonymous
// The current, incomplete, model for shader construction is:
// - Static code snippets (which can have an arbitrary signature) live in the Graphite
// pre-compiled modules, which are located at `src/sksl/sksl_graphite_frag.sksl` and
// `src/sksl/sksl_graphite_frag_es2.sksl`.
// - Glue code is generated in a `main` method which calls these static code snippets.
// The glue code is responsible for:
// 1) gathering the correct (mangled) uniforms
// 2) passing the uniforms and any other parameters to the helper method
// - The result of the final code snippet is then copied into "sk_FragColor".
// Note: each entry's 'fStaticFunctionName' field is expected to match the name of a function
// in the Graphite pre-compiled module, or be null if the preamble and expression generators are
// overridden to not use a static function.
void ShaderInfo::generateFragmentSkSL(const Caps* caps,
const ShaderCodeDictionary* dict,
const RenderStep* step,
UniquePaintParamsID paintID,
bool useStorageBuffers,
Swizzle writeSwizzle,
skia_private::TArray<SamplerDesc>* outDescs) {
PaintParamsKey key = dict->lookup(paintID);
SkASSERT(key.isValid()); // invalid keys should have been caught by invalid paint ID earlier
std::string label = key.toString(dict, /*includeData=*/false).c_str();
fRootNodes = key.getRootNodes(dict, &fShaderNodeAlloc);
// TODO(b/366220690): aggregateSnippetData() goes away entirely once the VulkanGraphicsPipeline
// is updated to use the extracted SamplerDescs directly.
for (const ShaderNode* root : fRootNodes) {
this->aggregateSnippetData(root);
}
#if defined(SK_DEBUG)
// Validate the root node structure of the key.
SkASSERT(fRootNodes.size() == 2 || fRootNodes.size() == 3);
// First node produces the source color (all snippets return a half4), so we just require that
// its signature takes no extra args or just local coords.
const ShaderSnippet* srcSnippet = dict->getEntry(fRootNodes[0]->codeSnippetId());
// TODO(b/349997190): Once SkEmptyShader doesn't use the passthrough snippet, we can assert
// that srcSnippet->needsPriorStageOutput() is false.
SkASSERT(!srcSnippet->needsBlenderDstColor());
// Second node is the final blender, so it must take both the src color and dst color, and not
// any local coordinate.
const ShaderSnippet* blendSnippet = dict->getEntry(fRootNodes[1]->codeSnippetId());
SkASSERT(blendSnippet->needsPriorStageOutput() && blendSnippet->needsBlenderDstColor());
SkASSERT(!blendSnippet->needsLocalCoords());
const ShaderSnippet* clipSnippet =
fRootNodes.size() > 2 ? dict->getEntry(fRootNodes[2]->codeSnippetId()) : nullptr;
SkASSERT(!clipSnippet ||
(!clipSnippet->needsPriorStageOutput() && !clipSnippet->needsBlenderDstColor()));
#endif
// The RenderStep should be performing shading since otherwise there's no need to generate a
// fragment shader program at all.
SkASSERT(step->performsShading());
// TODO(b/372912880): Release assert debugging for illegal instruction occurring in the wild.
SkASSERTF_RELEASE(step->performsShading(),
"render step: %s, label: %s",
step->name(),
label.c_str());
// Extract the root nodes for clarity
// TODO(b/372912880): Release assert debugging for illegal instruction occurring in the wild.
SkASSERTF_RELEASE(fRootNodes.size() == 2 || fRootNodes.size() == 3,
"root node size = %zu, label = %s",
fRootNodes.size(),
label.c_str());
const ShaderNode* const srcColorRoot = fRootNodes[0];
const ShaderNode* const finalBlendRoot = fRootNodes[1];
const ShaderNode* const clipRoot = fRootNodes.size() > 2 ? fRootNodes[2] : nullptr;
// Determine the algorithm for final blending: direct HW blending, coverage-modified HW
// blending (w/ or w/o dual-source blending) or via dst-read requirement.
Coverage finalCoverage = step->coverage();
if (finalCoverage == Coverage::kNone && SkToBool(clipRoot)) {
finalCoverage = Coverage::kSingleChannel;
}
std::optional<SkBlendMode> finalBlendMode;
if (finalBlendRoot->codeSnippetId() < kBuiltInCodeSnippetIDCount &&
finalBlendRoot->codeSnippetId() >= kFixedBlendIDOffset) {
finalBlendMode =
static_cast<SkBlendMode>(finalBlendRoot->codeSnippetId() - kFixedBlendIDOffset);
if (*finalBlendMode > SkBlendMode::kLastCoeffMode) {
// TODO(b/239726010): When we support advanced blend modes in HW, these modes could
// still be handled by fBlendInfo instead of SkSL
finalBlendMode.reset();
}
}
// The passed-in dstReadStrategy should only be used iff it is determined one is needed. If not,
// then manually assign fDstReadStrategy to kNoneRequired. ShaderInfo's dst read strategy
// informs the pipeline's via PipelineInfo created w/ shader info.
const bool dstReadRequired = IsDstReadRequired(caps, finalBlendMode, finalCoverage);
if (!dstReadRequired) {
fDstReadStrategy = DstReadStrategy::kNoneRequired;
} else {
SkASSERT(fDstReadStrategy != DstReadStrategy::kNoneRequired);
}
// TODO(b/372912880): Release assert debugging for illegal instruction occurring in the wild.
SkASSERTF_RELEASE(finalBlendMode.has_value() || dstReadRequired,
"blend mode: %d, dst read: %d, coverage: %d, label = %s",
finalBlendMode.has_value() ? (int)*finalBlendMode : -1,
(int) fDstReadStrategy,
(int) finalCoverage,
label.c_str());
const bool hasStepUniforms = step->numUniforms() > 0 && step->coverage() != Coverage::kNone;
const bool useStepStorageBuffer = useStorageBuffers && hasStepUniforms;
const bool useShadingStorageBuffer = useStorageBuffers && step->performsShading();
auto allReqFlags = srcColorRoot->requiredFlags() | finalBlendRoot->requiredFlags();
if (clipRoot) {
allReqFlags |= clipRoot->requiredFlags();
}
const bool useGradientStorageBuffer = caps->gradientBufferSupport() &&
(allReqFlags & SnippetRequirementFlags::kGradientBuffer);
const bool useDstSampler = fDstReadStrategy == DstReadStrategy::kTextureCopy ||
fDstReadStrategy == DstReadStrategy::kTextureSample;
std::vector<const ShaderNode*> liftedExpr;
collect_lifted_expressions(fRootNodes, liftedExpr);
const bool defineLocalCoordsVarying = this->needsLocalCoords();
std::string preamble = emit_varyings(step,
/*direction=*/"in",
liftedExpr,
/*emitSsboIndicesVarying=*/useShadingStorageBuffer,
defineLocalCoordsVarying);
// The uniforms are mangled by having their index in 'fEntries' as a suffix (i.e., "_%d")
const ResourceBindingRequirements& bindingReqs = caps->resourceBindingRequirements();
preamble += emit_intrinsic_constants(bindingReqs);
if (hasStepUniforms) {
if (useStepStorageBuffer) {
preamble += emit_render_step_storage_buffer(bindingReqs.fUniformsSetIdx,
bindingReqs.fRenderStepBufferBinding,
step->uniforms());
} else {
preamble += emit_render_step_uniforms(bindingReqs.fUniformsSetIdx,
bindingReqs.fRenderStepBufferBinding,
bindingReqs.fUniformBufferLayout,
step->uniforms());
}
}
bool wrotePaintColor = false;
if (useShadingStorageBuffer) {
preamble += emit_paint_params_storage_buffer(bindingReqs.fUniformsSetIdx,
bindingReqs.fPaintParamsBufferBinding,
fRootNodes,
&fHasPaintUniforms,
&wrotePaintColor);
SkSL::String::appendf(&preamble, "uint %s;\n", this->shadingSsboIndex());
} else {
preamble += emit_paint_params_uniforms(bindingReqs.fUniformsSetIdx,
bindingReqs.fPaintParamsBufferBinding,
bindingReqs.fUniformBufferLayout,
fRootNodes,
&fHasPaintUniforms,
&wrotePaintColor);
}
if (useGradientStorageBuffer) {
SkSL::String::appendf(&preamble,
"layout (set=%d, binding=%d) readonly buffer FSGradientBuffer {\n"
" float %s[];\n"
"};\n",
bindingReqs.fUniformsSetIdx,
bindingReqs.fGradientBufferBinding,
ShaderInfo::kGradientBufferName);
fHasGradientBuffer = true;
}
{
int binding = 0;
preamble += emit_textures_and_samplers(bindingReqs, fRootNodes, &binding, outDescs);
int paintTextureCount = binding;
if (step->hasTextures()) {
preamble += step->texturesAndSamplersSkSL(bindingReqs, &binding);
if (outDescs) {
// Determine how many render step samplers were used by comparing the binding value
// against paintTextureCount, taking into account the binding requirements. We
// assume and do not anticipate the render steps to use immutable samplers.
int renderStepSamplerCount = bindingReqs.fSeparateTextureAndSamplerBinding
? (binding - paintTextureCount) / 2
: binding - paintTextureCount;
// Add default SamplerDescs for all the dynamic samplers used by the render step so
// the size of outDescs will be equivalent to the total number of samplers.
outDescs->push_back_n(renderStepSamplerCount);
}
}
if (useDstSampler) {
preamble += EmitSamplerLayout(bindingReqs, &binding);
preamble += " sampler2D dstSampler;";
// Add default SamplerDesc for the intrinsic dstSampler to stay consistent with
// `fNumFragmentTexturesAndSamplers`.
if (outDescs) {
outDescs->push_back({});
}
}
// Record how many textures and samplers are used.
fNumFragmentTexturesAndSamplers = binding;
}
// Emit preamble declarations and helper functions required for snippets. In the default case
// this adds functions that bind a node's specific mangled uniforms to the snippet's
// implementation in the SkSL modules.
emit_preambles(*this, fRootNodes, /*treeLabel=*/"", &preamble);
std::string mainBody = "void main() {";
if (useShadingStorageBuffer) {
SkSL::String::appendf(&mainBody,
"%s = %s.y;\n",
this->shadingSsboIndex(),
RenderStep::ssboIndicesVarying());
}
if (step->emitsPrimitiveColor()) {
mainBody += "half4 primitiveColor;";
mainBody += step->fragmentColorSkSL();
} else {
SkASSERT(!(fRootNodes[0]->requiredFlags() & SnippetRequirementFlags::kPrimitiveColor));
}
// Using kDefaultArgs as the initial value means it will refer to undefined variables, but the
// root nodes should--at most--be depending on the coordinate when "needsLocalCoords" is true.
// If the PaintParamsKey violates that structure, this will produce SkSL compile errors.
ShaderSnippet::Args args = ShaderSnippet::kDefaultArgs;
args.fFragCoord = "localCoordsVar"; // the varying added in emit_varyings()
// TODO(b/349997190): The paint root node should not depend on any prior stage's output, but
// it can happen with how SkEmptyShader is currently mapped to `sk_passthrough`. In this case
// it requires that prior stage color to be transparent black. When SkEmptyShader can instead
// cause the draw to be skipped, this can go away.
args.fPriorStageOutput = "half4(0)";
// Calculate the src color and stash its output variable in `args`
args.fPriorStageOutput = srcColorRoot->invokeAndAssign(*this, args, &mainBody);
if (dstReadRequired) {
// Get the current dst color into a local variable, it may be used later on for coverage
// blending as well as the final blend.
mainBody += "half4 dstColor;";
if (useDstSampler) {
// dstReadBounds is in frag coords and already includes the replay translation. The
// reciprocol of the dstCopy dimensions are in ZW.
mainBody += "dstColor = sample(dstSampler,"
"dstReadBounds.zw*(sk_FragCoord.xy - dstReadBounds.xy));";
} else {
SkASSERT(fDstReadStrategy == DstReadStrategy::kFramebufferFetch);
mainBody += "dstColor = sk_LastFragColor;";
}
args.fBlenderDstColor = "dstColor";
args.fPriorStageOutput = finalBlendRoot->invokeAndAssign(*this, args, &mainBody);
finalBlendMode = SkBlendMode::kSrc;
}
if (writeSwizzle != Swizzle::RGBA()) {
SkSL::String::appendf(&mainBody, "%s = %s.%s;", args.fPriorStageOutput.c_str(),
args.fPriorStageOutput.c_str(),
writeSwizzle.asString().c_str());
}
if (finalCoverage == Coverage::kNone) {
// Either direct HW blending or a dst-read w/o any extra coverage. In both cases we just
// need to assign directly to sk_FragCoord and update the HW blend info to finalBlendMode.
SkASSERT(finalBlendMode.has_value());
// TODO(b/372912880): Release assert debugging for illegal instruction occurring in the wild
SkASSERTF_RELEASE(finalBlendMode.has_value(),
"blend mode: %d, dst read: %d, label = %s",
finalBlendMode.has_value() ? (int)*finalBlendMode : -1,
(int) fDstReadStrategy,
label.c_str());
fBlendInfo = gBlendTable[static_cast<int>(*finalBlendMode)];
SkSL::String::appendf(&mainBody, "sk_FragColor = %s;", args.fPriorStageOutput.c_str());
} else {
// Accumulate the output coverage. This will either modify the src color and secondary
// outputs for dual-source blending, or be combined directly with the in-shader blended
// final color if a dst-readback was required.
if (useStepStorageBuffer) {
SkSL::String::appendf(&mainBody,
"uint stepSsboIndex = %s.x;\n",
RenderStep::ssboIndicesVarying());
mainBody +=
emit_uniforms_from_storage_buffer("step", "stepSsboIndex", step->uniforms());
}
mainBody += "half4 outputCoverage = half4(1);";
mainBody += step->fragmentCoverageSkSL();
if (clipRoot) {
// The clip block node is invoked with device coords, not local coords like the main
// shading root node. However sk_FragCoord includes any replay translation and we
// need to recover the original device coordinate.
mainBody += "float2 devCoord = sk_FragCoord.xy - viewport.xy;";
args.fFragCoord = "devCoord";
std::string clipBlockOutput = clipRoot->invokeAndAssign(*this, args, &mainBody);
SkSL::String::appendf(&mainBody, "outputCoverage *= %s.a;", clipBlockOutput.c_str());
}
const char* outColor = args.fPriorStageOutput.c_str();
if (dstReadRequired) {
// If this draw uses a non-coherent dst read, we want to keep the existing dst color (or
// whatever has been previously drawn) when there's no coverage. This helps for batching
// text draws that need to read from a dst copy for blends. However, this only helps the
// case where the outer bounding boxes of each letter overlap and not two actual parts
// of the text.
if (useDstSampler) {
// We don't think any shaders actually output negative coverage, but just as a
// safety check for floating point precision errors, we compare with <= here. We
// just check the RGB values of the coverage, since the alpha may not have been set
// when using LCD. If we are using single-channel coverage, alpha will be equal to
// RGB anyway.
mainBody +=
"if (all(lessThanEqual(outputCoverage.rgb, half3(0)))) {"
"discard;"
"}";
}
// Use kSrc HW BlendInfo and do the coverage blend with dst in the shader.
fBlendInfo = gBlendTable[static_cast<int>(SkBlendMode::kSrc)];
SkSL::String::appendf(
&mainBody,
"sk_FragColor = %s * outputCoverage + dstColor * (1.0 - outputCoverage);",
outColor);
if (finalCoverage == Coverage::kLCD) {
SkSL::String::appendf(
&mainBody,
"half3 lerpRGB = mix(dstColor.aaa, %s.aaa, outputCoverage.rgb);"
"sk_FragColor.a = max(max(lerpRGB.r, lerpRGB.g), lerpRGB.b);",
outColor);
}
} else {
// Adjust the shader output(s) to incorporate the coverage so that HW blending produces
// the correct output.
// TODO: Determine whether draw is opaque and pass that to GetBlendFormula.
// TODO(b/372912880): Release assert debugging for illegal instruction
SkASSERTF_RELEASE(finalBlendMode.has_value(),
"blend mode: %d, dst read: %d, coverage: %d, label = %s",
finalBlendMode.has_value() ? (int)*finalBlendMode : -1,
(int) fDstReadStrategy,
(int) finalCoverage,
label.c_str());
BlendFormula coverageBlendFormula =
finalCoverage == Coverage::kLCD
? skgpu::GetLCDBlendFormula(*finalBlendMode)
: skgpu::GetBlendFormula(
/*isOpaque=*/false, /*hasCoverage=*/true, *finalBlendMode);
fBlendInfo = {coverageBlendFormula.equation(),
coverageBlendFormula.srcCoeff(),
coverageBlendFormula.dstCoeff(),
SK_PMColor4fTRANSPARENT,
coverageBlendFormula.modifiesDst()};
if (finalCoverage == Coverage::kLCD) {
mainBody += "outputCoverage.a = max(max(outputCoverage.r, "
"outputCoverage.g), "
"outputCoverage.b);";
}
mainBody += emit_color_output(coverageBlendFormula.primaryOutput(),
"sk_FragColor",
outColor);
if (coverageBlendFormula.hasSecondaryOutput()) {
SkASSERT(caps->shaderCaps()->fDualSourceBlendingSupport);
mainBody += emit_color_output(coverageBlendFormula.secondaryOutput(),
"sk_SecondaryFragColor",
outColor);
}
}
}
mainBody += "}\n";
fFragmentSkSL = preamble + "\n" + mainBody;
fFSLabel = writeSwizzle.asString().c_str();
fFSLabel += " + ";
fFSLabel = step->name();
fFSLabel += " + ";
fFSLabel += label;
if (fDstReadStrategy != DstReadStrategy::kNoneRequired) {
fFSLabel += " + Dst Read (";
fFSLabel += dst_read_strategy_to_str(fDstReadStrategy);
fFSLabel += ")";
}
}
void ShaderInfo::generateVertexSkSL(const Caps* caps,
const RenderStep* step,
bool useStorageBuffers) {
const bool hasStepUniforms = step->numUniforms() > 0;
const bool useStepStorageBuffer = useStorageBuffers && hasStepUniforms;
const bool useShadingStorageBuffer = useStorageBuffers && step->performsShading();
const bool defineLocalCoordsVarying = this->needsLocalCoords();
// Fixed program header (intrinsics are always declared as an uniform interface block)
const ResourceBindingRequirements& bindingReqs = caps->resourceBindingRequirements();
std::string sksl = emit_intrinsic_constants(bindingReqs);
if (step->numVertexAttributes() > 0 || step->numInstanceAttributes() > 0) {
int attr = 0;
auto add_attrs = [&sksl, &attr](SkSpan<const Attribute> attrs) {
for (auto a : attrs) {
SkSL::String::appendf(&sksl, " layout(location=%d) in ", attr++);
sksl.append(SkSLTypeString(a.gpuType()));
SkSL::String::appendf(&sksl, " %s;\n", a.name());
}
};
if (step->numVertexAttributes() > 0) {
#if defined(SK_DEBUG)
sksl.append("// vertex attrs\n");
#endif
add_attrs(step->vertexAttributes());
}
if (step->numInstanceAttributes() > 0) {
#if defined(SK_DEBUG)
sksl.append("// instance attrs\n");
#endif
add_attrs(step->instanceAttributes());
}
}
// Uniforms needed by RenderStep
// The uniforms are mangled by having their index in 'fEntries' as a suffix (i.e., "_%d")
if (hasStepUniforms) {
if (useStepStorageBuffer) {
sksl += emit_render_step_storage_buffer(bindingReqs.fUniformsSetIdx,
bindingReqs.fRenderStepBufferBinding,
step->uniforms());
} else {
sksl += emit_render_step_uniforms(bindingReqs.fUniformsSetIdx,
bindingReqs.fRenderStepBufferBinding,
bindingReqs.fUniformBufferLayout,
step->uniforms());
}
}
std::vector<const ShaderNode*> liftedExpr;
collect_lifted_expressions(fRootNodes, liftedExpr);
if (!liftedExpr.empty()) {
bool unusedHasPaintUniforms = false;
bool unusedWrotePaintColor = false;
if (useShadingStorageBuffer) {
sksl += emit_paint_params_storage_buffer(bindingReqs.fUniformsSetIdx,
bindingReqs.fPaintParamsBufferBinding,
fRootNodes,
&unusedHasPaintUniforms,
&unusedWrotePaintColor);
} else {
sksl += emit_paint_params_uniforms(bindingReqs.fUniformsSetIdx,
bindingReqs.fPaintParamsBufferBinding,
bindingReqs.fUniformBufferLayout,
fRootNodes,
&unusedHasPaintUniforms,
&unusedWrotePaintColor);
}
}
// Varyings needed by RenderStep
sksl += emit_varyings(
step, "out", liftedExpr, useShadingStorageBuffer, defineLocalCoordsVarying);
// Vertex shader function declaration
sksl += "void main() {";
// Create stepLocalCoords which render steps can write to.
sksl += "float2 stepLocalCoords = float2(0);";
// Vertex shader body
if (useStepStorageBuffer) {
// Extract out render step uniforms from SSBO, declaring local variables with the expected
// uniform names so that RenderStep SkSL is independent of storage choice.
SkSL::String::appendf(
&sksl, "uint stepSsboIndex = %s.x;\n", RenderStep::ssboIndicesAttribute());
sksl += emit_uniforms_from_storage_buffer("step", "stepSsboIndex", step->uniforms());
}
sksl += step->vertexSkSL();
// We want to map the rectangle of logical device pixels from (0,0) to (viewWidth, viewHeight)
// to normalized device coordinates: (-1,-1) to (1,1) (actually -w to w since it's before
// homogenous division).
//
// For efficiency, this assumes viewport.zw holds the reciprocol of twice the viewport width and
// height. On some backends the NDC Y axis is flipped relative to the device and
// viewport coords (i.e. it points up instead of down). In those cases, it's also assumed that
// viewport.w holds a negative value. In that case the sign(viewport.zw) changes from
// subtracting w to adding w.
sksl += "sk_Position = float4(viewport.zw*devPosition.xy - sign(viewport.zw)*devPosition.ww,"
"devPosition.zw);";
if (useShadingStorageBuffer) {
// Assign SSBO index values to the SSBO index varying.
SkSL::String::appendf(&sksl,
"%s = %s;",
RenderStep::ssboIndicesVarying(),
RenderStep::ssboIndicesAttribute());
}
if (defineLocalCoordsVarying) {
// Assign Render Step's stepLocalCoords to the localCoordsVar varying.
sksl += "localCoordsVar = stepLocalCoords;";
}
if (!liftedExpr.empty()) {
// If we're reading uniforms from a storage buffer, emit the SSBO index first.
if (this->shadingSsboIndex()) {
SkSL::String::appendf(&sksl,
"uint %s = %s.y;\n",
this->shadingSsboIndex(),
RenderStep::ssboIndicesAttribute());
}
for (const ShaderNode* node : liftedExpr) {
ShaderSnippet::Args args = ShaderSnippet::kDefaultArgs;
args.fFragCoord = "stepLocalCoords"; // Render Step's stepLocalCoords
std::string varName = node->getExpressionVarying();
std::string expression = node->entry()->fLiftableExpressionGenerator(*this, node, args);
SkSL::String::appendf(&sksl, "%s = %s;", varName.c_str(), expression.c_str());
}
}
sksl += "}";
fVertexSkSL = std::move(sksl);
fVSLabel = step->name();
if (defineLocalCoordsVarying) {
fVSLabel += " (w/ local coords)";
}
fHasStepUniforms = hasStepUniforms;
}
bool ShaderInfo::needsLocalCoords() const {
return !fRootNodes.empty() &&
SkToBool(fRootNodes[0]->requiredFlags() & SnippetRequirementFlags::kLocalCoords);
}
void ShaderInfo::aggregateSnippetData(const ShaderNode* node) {
if (!node) {
return;
}
// Accumulate data of children first.
for (const ShaderNode* child : node->children()) {
this->aggregateSnippetData(child);
}
if (node->requiredFlags() & SnippetRequirementFlags::kStoresSamplerDescData &&
!node->data().empty()) {
fData.push_back_n(node->data().size(), node->data().data());
}
}
} // namespace skgpu::graphite