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// Copyright 2021 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 <utility>
#include "src/tint/ast/struct_member.h"
#include "src/tint/sem/binding_point.h"
#include "src/tint/sem/builtin_type.h"
#include "src/tint/transform/transform.h"
namespace tint::transform {
/// BindingPoint is an alias to sem::BindingPoint
using BindingPoint = sem::BindingPoint;
/// Within the MultiplanarExternalTexture transform, each instance of a
/// texture_external binding is unpacked into two texture_2d<f32> bindings
/// representing two possible planes of a texture and a uniform buffer binding
/// representing a struct of parameters. Calls to textureLoad or
/// textureSampleLevel that contain a texture_external parameter will be
/// transformed into a newly generated version of the function, which can
/// perform the desired operation on a single RGBA plane or on separate Y and UV
/// planes, and do colorspace conversions including yuv->rgb conversion, gamma
/// decoding, gamut conversion, and gamma encoding steps. Specifically
// for BT.709 to SRGB conversion, it takes the fast path only doing the yuv->rgb
// step and skipping all other steps.
class MultiplanarExternalTexture final : public Castable<MultiplanarExternalTexture, Transform> {
/// This struct identifies the binding groups and locations for new bindings to
/// use when transforming a texture_external instance.
struct BindingPoints {
/// The desired binding location of the texture_2d representing plane #1 when
/// a texture_external binding is expanded.
BindingPoint plane_1;
/// The desired binding location of the ExternalTextureParams uniform when a
/// texture_external binding is expanded.
BindingPoint params;
/// Reflect the fields of this class so that it can be used by tint::ForeachField()
TINT_REFLECT(plane_1, params);
/// BindingsMap is a map where the key is the binding location of a
/// texture_external and the value is a struct containing the desired
/// locations for new bindings expanded from the texture_external instance.
using BindingsMap = std::unordered_map<BindingPoint, BindingPoints>;
/// NewBindingPoints is consumed by the MultiplanarExternalTexture transform.
/// Data holds information about location of each texture_external binding and
/// which binding slots it should expand into.
struct NewBindingPoints final : public Castable<Data, transform::Data> {
/// Constructor
/// @param bm a map to the new binding slots to use.
explicit NewBindingPoints(BindingsMap bm);
/// Destructor
~NewBindingPoints() override;
/// A map of new binding points to use.
const BindingsMap bindings_map;
/// Constructor
/// Destructor
~MultiplanarExternalTexture() override;
/// @copydoc Transform::Apply
ApplyResult Apply(const Program* program,
const DataMap& inputs,
DataMap& outputs) const override;
struct State;
} // namespace tint::transform