skgpu::graphite::ShaderInfo Class Reference

#include <ShaderCodeDictionary.h>

Public Member Functions
	ShaderInfo (UniquePaintParamsID id, const ShaderCodeDictionary *dict, const RuntimeEffectDictionary *rteDict, const char *ssboIndex)
bool	needsLocalCoords () const
bool	needsSurfaceColor () const
const RuntimeEffectDictionary *	runtimeEffectDictionary () const
const char *	ssboIndex () const
const skgpu::BlendInfo &	blendInfo () const
std::string	toSkSL (const Caps *caps, const RenderStep *step, bool useStorageBuffers, int *numTexturesAndSamplersUsed, int *numPaintUniforms, int *renderStepUniformTotalBytes, int *paintUniformsTotalBytes, Swizzle writeSwizzle)

Detailed Description

Definition at line 173 of file ShaderCodeDictionary.h.

Constructor & Destructor Documentation

ShaderInfo()

skgpu::graphite::ShaderInfo::ShaderInfo	(	UniquePaintParamsID	id,
		const ShaderCodeDictionary *	dict,
		const RuntimeEffectDictionary *	rteDict,
		const char *	ssboIndex
	)

Definition at line 187 of file ShaderCodeDictionary.cpp.

        : fRuntimeEffectDictionary(rteDict)
        , fSsboIndex(ssboIndex)
        , fSnippetRequirementFlags(SnippetRequirementFlags::kNone) {
    PaintParamsKey key = dict->lookup(id);
    SkASSERT(key.isValid()); // invalid keys should have been caught by invalid paint ID earlier
 
    fRootNodes = key.getRootNodes(dict, &fShaderNodeAlloc);
    // Aggregate snippet requirements across root nodes and look for fixed-function blend IDs in
    // the root to initialize the HW blend info.
    SkDEBUGCODE(bool fixedFuncBlendFound = false;)
    for (const ShaderNode* root : fRootNodes) {
        // TODO: This is brittle as it relies on PaintParams::toKey() putting the final fixed
        // function blend block at the root level. This can be improved with more structure to the
        // key creation.
        if (root->codeSnippetId() < kBuiltInCodeSnippetIDCount &&
            root->codeSnippetId() >= kFixedFunctionBlendModeIDOffset) {
            SkASSERT(root->numChildren() == 0);
            // This should occur at most once
            SkASSERT(!fixedFuncBlendFound);
            SkDEBUGCODE(fixedFuncBlendFound = true;)
 
            fBlendMode = static_cast<SkBlendMode>(root->codeSnippetId() -
                                                  kFixedFunctionBlendModeIDOffset);
            SkASSERT(static_cast<int>(fBlendMode) >= 0 &&
                     fBlendMode <= SkBlendMode::kLastCoeffMode);
            fBlendInfo = gBlendTable[static_cast<int>(fBlendMode)];
        } else {
            fSnippetRequirementFlags |= root->requiredFlags();
        }
    }
}

Member Function Documentation

blendInfo()

const skgpu::BlendInfo & skgpu::graphite::ShaderInfo::blendInfo ( ) const

inline

Definition at line 191 of file ShaderCodeDictionary.h.

{ return fBlendInfo; }

needsLocalCoords()

bool skgpu::graphite::ShaderInfo::needsLocalCoords ( ) const

inline

Definition at line 180 of file ShaderCodeDictionary.h.

                                  {
        return SkToBool(fSnippetRequirementFlags & SnippetRequirementFlags::kLocalCoords);
    }

needsSurfaceColor()

bool skgpu::graphite::ShaderInfo::needsSurfaceColor ( ) const

inline

Definition at line 183 of file ShaderCodeDictionary.h.

                                   {
        return SkToBool(fSnippetRequirementFlags & SnippetRequirementFlags::kSurfaceColor);
    }

runtimeEffectDictionary()

const RuntimeEffectDictionary * skgpu::graphite::ShaderInfo::runtimeEffectDictionary ( ) const

inline

Definition at line 186 of file ShaderCodeDictionary.h.

                                                                   {
        return fRuntimeEffectDictionary;
    }

ssboIndex()

const char * skgpu::graphite::ShaderInfo::ssboIndex ( ) const

inline

Definition at line 189 of file ShaderCodeDictionary.h.

{ return fSsboIndex; }

toSkSL()

std::string skgpu::graphite::ShaderInfo::toSkSL	(	const Caps *	caps,
		const RenderStep *	step,
		bool	useStorageBuffers,
		int *	numTexturesAndSamplersUsed,
		int *	numPaintUniforms,
		int *	renderStepUniformTotalBytes,
		int *	paintUniformsTotalBytes,
		Swizzle	writeSwizzle
	)

Definition at line 265 of file ShaderCodeDictionary.cpp.

                                                     {
    // If we're doing analytic coverage, we must also be doing shading.
    SkASSERT(step->coverage() == Coverage::kNone || step->performsShading());
    const bool hasStepUniforms = step->numUniforms() > 0 && step->coverage() != Coverage::kNone;
    const bool useStepStorageBuffer = useStorageBuffers && hasStepUniforms;
    const bool useShadingStorageBuffer = useStorageBuffers && step->performsShading();
 
    const bool defineLocalCoordsVarying = this->needsLocalCoords();
    std::string preamble = EmitVaryings(step,
                                        /*direction=*/"in",
                                        /*emitSsboIndicesVarying=*/useShadingStorageBuffer,
                                        defineLocalCoordsVarying);
 
    // The uniforms are mangled by having their index in 'fEntries' as a suffix (i.e., "_%d")
    // TODO: replace hard-coded bufferIDs with the backend's step and paint uniform-buffer indices.
    // TODO: The use of these indices is Metal-specific. We should replace these functions with
    // API-independent ones.
    const ResourceBindingRequirements& bindingReqs = caps->resourceBindingRequirements();
    if (hasStepUniforms) {
        if (useStepStorageBuffer) {
            preamble += EmitRenderStepStorageBuffer(/*bufferID=*/1, step->uniforms());
        } else {
            preamble += EmitRenderStepUniforms(/*bufferID=*/1,
                                               bindingReqs.fUniformBufferLayout,
                                               step->uniforms(),
                                               renderStepUniformTotalBytes);
        }
    }
 
    bool wrotePaintColor = false;
    if (useShadingStorageBuffer) {
        preamble += EmitPaintParamsStorageBuffer(/*bufferID=*/2,
                                                 fRootNodes,
                                                 numPaintUniforms,
                                                 &wrotePaintColor);
        SkSL::String::appendf(&preamble, "uint %s;\n", this->ssboIndex());
    } else {
        preamble += EmitPaintParamsUniforms(/*bufferID=*/2,
                                            bindingReqs.fUniformBufferLayout,
                                            fRootNodes,
                                            numPaintUniforms,
                                            paintUniformsTotalBytes,
                                            &wrotePaintColor);
    }
 
    {
        int binding = 0;
        preamble += EmitTexturesAndSamplers(bindingReqs, fRootNodes, &binding);
        if (step->hasTextures()) {
            preamble += step->texturesAndSamplersSkSL(bindingReqs, &binding);
        }
 
        // Report back to the caller how many textures and samplers are used.
        if (numTexturesAndSamplersUsed) {
            *numTexturesAndSamplersUsed = binding;
        }
    }
 
    if (step->emitsPrimitiveColor()) {
        // TODO: Define this in the main body, and then pass it down into snippets like we do with
        // the local coordinates varying.
        preamble += "half4 primitiveColor;";
    }
 
    // 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() {";
    // Set initial color. This will typically be optimized out by SkSL in favor of the paint
    // specifying a color with a solid color shader.
    mainBody += "half4 initialColor = half4(0);";
 
    if (useShadingStorageBuffer) {
        SkSL::String::appendf(&mainBody,
                              "%s = %s.y;\n",
                              this->ssboIndex(),
                              RenderStep::ssboIndicesVarying());
    }
 
    if (step->emitsPrimitiveColor()) {
        mainBody += step->fragmentColorSkSL();
    }
 
    // While looping through root nodes to emit shader code, skip the clip shader node if it's found
    // and keep it to apply later during coverage calculation.
    const ShaderNode* clipShaderNode = nullptr;
 
    // Emit shader main body code, invoking each root node's expression, forwarding the previous
    // node's output to the next.
    static constexpr char kUnusedDstColor[] = "half4(1)";
    static constexpr char kUnusedLocalCoords[] = "float2(0)";
    ShaderSnippet::Args args = {"initialColor",
                                kUnusedDstColor,
                                this->needsLocalCoords() ? "localCoordsVar" : kUnusedLocalCoords};
    for (const ShaderNode* node : fRootNodes) {
        if (node->codeSnippetId() == (int) BuiltInCodeSnippetID::kClipShader) {
            SkASSERT(!clipShaderNode);
            clipShaderNode = node;
            continue;
        }
        // This exclusion of the final Blend can be removed once we've resolved the final
        // blend parenting issue w/in the key
        if (node->codeSnippetId() >= kBuiltInCodeSnippetIDCount ||
            node->codeSnippetId() < kFixedFunctionBlendModeIDOffset) {
            args.fPriorStageOutput = emit_glue_code_for_entry(*this, node, args, &mainBody);
        }
    }
 
    if (writeSwizzle != Swizzle::RGBA()) {
        SkSL::String::appendf(&mainBody, "%s = %s.%s;", args.fPriorStageOutput.c_str(),
                                                        args.fPriorStageOutput.c_str(),
                                                        writeSwizzle.asString().c_str());
    }
 
    const char* outColor = args.fPriorStageOutput.c_str();
    const Coverage coverage = step->coverage();
    if (coverage != Coverage::kNone || clipShaderNode) {
        if (useStepStorageBuffer) {
            SkSL::String::appendf(&mainBody,
                                  "uint stepSsboIndex = %s.x;\n",
                                  RenderStep::ssboIndicesVarying());
            mainBody += EmitUniformsFromStorageBuffer("step", "stepSsboIndex", step->uniforms());
        }
 
        mainBody += "half4 outputCoverage = half4(1);";
        mainBody += step->fragmentCoverageSkSL();
 
        if (clipShaderNode) {
            std::string clipShaderOutput =
                    emit_glue_code_for_entry(*this, clipShaderNode, args, &mainBody);
            SkSL::String::appendf(&mainBody, "outputCoverage *= %s.a;", clipShaderOutput.c_str());
        }
 
        // TODO: Determine whether draw is opaque and pass that to GetBlendFormula.
        BlendFormula coverageBlendFormula =
                coverage == Coverage::kLCD
                        ? skgpu::GetLCDBlendFormula(fBlendMode)
                        : skgpu::GetBlendFormula(
                                  /*isOpaque=*/false, /*hasCoverage=*/true, fBlendMode);
 
        if (this->needsSurfaceColor()) {
            // 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.
            DstReadRequirement dstReadReq = caps->getDstReadRequirement();
            if (dstReadReq == DstReadRequirement::kTextureCopy ||
                dstReadReq == DstReadRequirement::kTextureSample) {
                // 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 originally-specified BlendInfo and blend with dst manually.
            SkSL::String::appendf(
                    &mainBody,
                    "sk_FragColor = %s * outputCoverage + surfaceColor * (1.0 - outputCoverage);",
                    outColor);
            if (coverage == Coverage::kLCD) {
                SkSL::String::appendf(
                        &mainBody,
                        "half3 lerpRGB = mix(surfaceColor.aaa, %s.aaa, outputCoverage.rgb);"
                        "sk_FragColor.a = max(max(lerpRGB.r, lerpRGB.g), lerpRGB.b);",
                        outColor);
            }
 
        } else {
            fBlendInfo = {coverageBlendFormula.equation(),
                          coverageBlendFormula.srcCoeff(),
                          coverageBlendFormula.dstCoeff(),
                          SK_PMColor4fTRANSPARENT,
                          coverageBlendFormula.modifiesDst()};
 
            if (coverage == Coverage::kLCD) {
                mainBody += "outputCoverage.a = max(max(outputCoverage.r, "
                                                       "outputCoverage.g), "
                                                   "outputCoverage.b);";
            }
            append_color_output(
                    &mainBody, coverageBlendFormula.primaryOutput(), "sk_FragColor", outColor);
            if (coverageBlendFormula.hasSecondaryOutput()) {
                append_color_output(&mainBody,
                                    coverageBlendFormula.secondaryOutput(),
                                    "sk_SecondaryFragColor",
                                    outColor);
            }
        }
 
    } else {
        SkSL::String::appendf(&mainBody, "sk_FragColor = %s;", outColor);
    }
    mainBody += "}\n";
 
    return preamble + "\n" + mainBody;
}

---

The documentation for this class was generated from the following files:

• third_party/skia/src/gpu/graphite/ShaderCodeDictionary.h
• third_party/skia/src/gpu/graphite/ShaderCodeDictionary.cpp