chromium/third_party/angle/src/compiler/translator/tree_ops/spirv/ReswizzleYUVOps.cpp

//
// Copyright 2022 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// ReswizzleYUVOps: Adjusts swizzles for YUV channel order difference between
//   GLES and Vulkan
//
//

#include "compiler/translator/tree_ops/spirv/EmulateYUVBuiltIns.h"

#include "compiler/translator/StaticType.h"
#include "compiler/translator/SymbolTable.h"
#include "compiler/translator/tree_util/IntermNode_util.h"
#include "compiler/translator/tree_util/IntermTraverse.h"
#include "compiler/translator/tree_util/RunAtTheEndOfShader.h"

namespace sh
{
namespace
{
// A traverser that adjusts channel order for various yuv ops.
class ReswizzleYUVOpsTraverser : public TIntermTraverser
{ … };

// OpenGLES and Vulkan has different color component mapping for YUV. OpenGL spec maps R_gl=y,
// G_gl=u, B_gl=v, but Vulkan wants R_vulkan=v, G_vulkan=y, B_vulkan=u. We want all calculation to
// be in OpenGLES mapping during shader execution, but the actual buffer/image will be stored as
// vulkan mapping. This means when we sample from VkImage, we need to map from vulkan order back to
// GL order, which comes out to be R_gl=y=G_vulkan=1, G_gl=u=B_vulkan=2, B_gl=v=R_vulkan=0. i.e, {1,
// 2, 0, 3}. This function will check if the aggregate is a texture{proj|fetch}(samplerExternal,...)
// and if yes it will compose and return a swizzle node.
TIntermSwizzle *CheckTextureOpWithSamplerExternal2DY2YAndSwizzle(Visit visit,
                                                                 TIntermAggregate *node)
{ … }

bool ReswizzleYUVOpsTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
{ … }

bool ReswizzleYUVOpsTraverser::visitSwizzle(Visit visit, TIntermSwizzle *node)
{ … }

// OpenGLES and Vulkan has different color component mapping for YUV. When we write YUV data, we
// need to convert OpenGL mapping to vulkan's mapping, which comes out to be {2, 0, 1, 3}.
bool ReswizzleYUVOpsTraverser::adjustOutput(TCompiler *compiler,
                                            TIntermBlock *root,
                                            const TIntermSymbol &yuvOutput)
{ … }
}  // anonymous namespace

bool ReswizzleYUVOps(TCompiler *compiler,
                     TIntermBlock *root,
                     TSymbolTable *symbolTable,
                     const TIntermSymbol *yuvOutput)
{ … }
}  // namespace sh