93 lines
3.2 KiB
C
93 lines
3.2 KiB
C
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/*
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* Copyright 2020 Google LLC
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkSLSampleUsage_DEFINED
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#define SkSLSampleUsage_DEFINED
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#include <string>
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namespace SkSL {
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/**
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* Represents all of the ways that a fragment processor is sampled by its parent.
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*/
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struct SampleUsage {
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enum class Kind {
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// No sample(child, matrix) call affects the FP.
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kNone,
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// The FP is sampled with a matrix whose value is fixed and based only on literals or
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// uniforms, and thus the transform can be hoisted to the vertex shader (assuming that
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// its parent can also be hoisted, i.e. not sampled explicitly).
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kUniform,
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// The FP is sampled with a non-literal/uniform value, or matrix-sampled multiple times,
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// and thus the transform cannot be hoisted to the vertex shader.
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kVariable
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};
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// Make a SampleUsage that corresponds to no sampling of the child at all
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SampleUsage() = default;
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// This corresponds to sample(child, color, matrix) calls where every call site in the FP has
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// the same matrix, and that matrix's value is uniform (some expression only involving literals
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// and uniform variables).
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static SampleUsage UniformMatrix(std::string expression, bool hasPerspective = true) {
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return SampleUsage(Kind::kUniform, std::move(expression), hasPerspective, false, false);
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}
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// This corresponds to sample(child, color, matrix) where the 3rd argument is an expression that
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// can't be hoisted to the vertex shader, or where the expression used is not the same at all
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// call sites in the FP.
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static SampleUsage VariableMatrix(bool hasPerspective = true) {
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return SampleUsage(Kind::kVariable, "", hasPerspective, false, false);
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}
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static SampleUsage Explicit() {
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return SampleUsage(Kind::kNone, "", false, true, false);
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}
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static SampleUsage PassThrough() {
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return SampleUsage(Kind::kNone, "", false, false, true);
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}
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SampleUsage merge(const SampleUsage& other);
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bool isSampled() const {
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return this->hasMatrix() || fExplicitCoords || fPassThrough;
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}
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bool hasMatrix() const { return fKind != Kind::kNone; }
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bool hasUniformMatrix() const { return fKind == Kind::kUniform; }
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bool hasVariableMatrix() const { return fKind == Kind::kVariable; }
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Kind fKind = Kind::kNone;
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// The uniform expression representing the matrix (only valid when kind == kUniform)
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std::string fExpression;
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// FIXME: We can expand this to track a more general matrix type to allow for optimizations on
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// identity or scale+translate matrices too.
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bool fHasPerspective = false;
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bool fExplicitCoords = false;
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bool fPassThrough = false;
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SampleUsage(Kind kind,
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std::string expression,
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bool hasPerspective,
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bool explicitCoords,
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bool passThrough)
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: fKind(kind)
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, fExpression(expression)
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, fHasPerspective(hasPerspective)
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, fExplicitCoords(explicitCoords)
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, fPassThrough(passThrough) {}
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std::string constructor(std::string perspectiveExpression) const;
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};
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} // namespace
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#endif
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