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// Copyright 2023 The Tint Authors.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <unordered_map>
#include <unordered_set>
#include "src/tint/api/common/binding_point.h"
#include "src/tint/api/options/texture_builtins_from_uniform.h"
#include "src/tint/lang/wgsl/ast/transform/transform.h"
// Forward declarations
namespace tint {
class CloneContext;
} // namespace tint
namespace tint::glsl::writer {
/// TextureBuiltinsFromUniform is a transform that implements calls to textureNumLevels() and
/// textureNumSamples() by retrieving the texture information from a uniform buffer, as those
/// builtin functions are not available in some version of GLSL.
/// The generated uniform buffer will have the form:
/// ```
/// struct internal_uniform {
/// texture_builtin_value_0 : u32,
/// };
/// @group(0) @binding(0) var tex : texture_2d<f32>;
/// ```
/// The binding group and number used for this uniform buffer are provided via
/// the `Config` transform input.
/// The transform coverts the texture builtins calls into values lookup from the internal
/// buffer. If the texture is a function parameter instead of a global variable, this transform
/// also takes care of adding extra paramters and arguments to these functions and their callsites.
/// This transform must run before `CombineSamplers` transform so that the binding point of the
/// original texture object can be preserved.
class TextureBuiltinsFromUniform final
: public Castable<TextureBuiltinsFromUniform, ast::transform::Transform> {
/// Constructor
/// Destructor
~TextureBuiltinsFromUniform() override;
/// Configuration options for the TextureBuiltinsFromUniform transform.
struct Config final : public Castable<Config, ast::transform::Data> {
/// Constructor
/// @param ubo_bp the binding point to use for the generated uniform buffer.
explicit Config(BindingPoint ubo_bp);
/// Copy constructor
Config(const Config&);
/// Copy assignment
/// @return this Config
Config& operator=(const Config&);
/// Destructor
~Config() override;
/// The binding point to use for the generated uniform buffer.
BindingPoint ubo_binding;
/// Information produced about what the transform did.
/// If there were no calls to the textureNumLevels() or textureNumSamples() builtin, then no
/// Result will be emitted.
struct Result final : public Castable<Result, ast::transform::Data> {
/// Using for shorter names
/// Records the field and the byte offset of the data to push in the internal uniform
/// buffer.
using FieldAndOffset = TextureBuiltinsFromUniformOptions::FieldAndOffset;
/// Maps from binding point to data entry with the information to populate the data.
using BindingPointToFieldAndOffset =
/// Constructor
/// @param bindpoint_to_data_in mapping from binding points of global texture variables to
/// the byte offsets and data types needed to be pushed into the internal uniform buffer.
explicit Result(BindingPointToFieldAndOffset bindpoint_to_data_in);
/// Copy constructor
Result(const Result&);
/// Destructor
~Result() override;
/// A map of global texture variable binding point to the byte offset and data type to push
/// into the internal uniform buffer.
BindingPointToFieldAndOffset bindpoint_to_data;
/// @copydoc ast::transform::Transform::Apply
ApplyResult Apply(const Program& program,
const ast::transform::DataMap& inputs,
ast::transform::DataMap& outputs) const override;
struct State;
} // namespace tint::glsl::writer