CopyCompressShader.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "GlobalShader.h"
#include "SceneView.h"
#include "ShaderParameterMacros.h"
#include "ShaderParameterStruct.h"
 
class FCopyCompressCS : public FGlobalShader
{
public:
    DECLARE_GLOBAL_SHADER(FCopyCompressCS);
    SHADER_USE_PARAMETER_STRUCT(FCopyCompressCS, FGlobalShader);
 
    BEGIN_SHADER_PARAMETER_STRUCT(FParameters, )
        SHADER_PARAMETER_SRV(Texture2D, SourceTextureA)
        SHADER_PARAMETER_RDG_TEXTURE_SRV(Texture2D, SourceTextureB)
        SHADER_PARAMETER_SAMPLER(SamplerState, TextureSampler)
        SHADER_PARAMETER_RDG_TEXTURE_UAV(RWTexture2D, DestTexture)
        SHADER_PARAMETER_RDG_TEXTURE_UAV(RWTexture2D, DestCompressTexture_64bit)
        SHADER_PARAMETER_RDG_TEXTURE_UAV(RWTexture2D, DestCompressTexture_128bit)
        SHADER_PARAMETER(FVector2f, SourceUV)
        SHADER_PARAMETER(FVector2f, TexelSize)
        SHADER_PARAMETER(FVector2f, TexelOffsets)
        SHADER_PARAMETER(FIntVector4, DestRect)
    END_SHADER_PARAMETER_STRUCT()
 
    static constexpr int32 GroupSize = 8;
 
    class FSourceTextureSelector : SHADER_PERMUTATION_BOOL("SOURCE_TEXTURE_A");
    class FDestSrgb : SHADER_PERMUTATION_BOOL("TEXTURE_SRGB");
    class FCompressionFormatDim : SHADER_PERMUTATION_INT("COMPRESSION_FORMAT", 7);
    using FPermutationDomain = TShaderPermutationDomain<FSourceTextureSelector, FDestSrgb, FCompressionFormatDim>;
 
    static int32 GetCompressionPermutation(EPixelFormat InFormat)
    {
        const EPixelFormat CompressedFormats[] = { PF_DXT1, PF_DXT5, PF_BC4, PF_BC5, PF_BC6H, PF_BC7 };
        return MakeArrayView(CompressedFormats).Find(InFormat) + 1;
    }
};