CopyTextureCS

UE 5.0

D:\Program Files\Epic Games\UE_5.0\Engine\Source\Runtime\RenderCore\Public\CopyTextureShader.h

클래스 선언은 다음과 같습니다.

class FCopyTextureCS : public FGlobalShader
{
	DECLARE_EXPORTED_TYPE_LAYOUT(FCopyTextureCS, RENDERCORE_API, NonVirtual);
    ...

ComputeShader는 GlobalShader를 상속받습니다.
DECLARE_EXPORTED_TYPE_LAYOUT란?
- D:\Program Files\Epic Games\UE_5.0\Engine\Source\Runtime\Core\Public\Serialization\MemoryLayout.h에서 찾을 수 있습니다.
- (T, RequiredAPI, Interface)를 파라메터로 받고,
- 정의는 INTERNAL_DECLARE_LAYOUT_BASE(T); INTERNAL_DECLARE_TYPE_LAYOUT(T, Interface, RequiredAPI)입니다.
cpp를 보면 다음과 같이 되어있습니다.
```
IMPLEMENT_TYPE_LAYOUT(FCopyTextureCS);
```

추가적으로 다음과 같이 되어있습니다.

```cpp #define IMPLEMENT_COPY_RESOURCE_SHADER(SrcType,DstType,ValueType)\ typedef TCopyResourceCS<ECopyTextureResourceType::SrcType, ECopyTextureResourceType::DstType, ECopyTextureValueType::ValueType, 4> FCopyTextureCS_##SrcType##_##DstType##_##ValueType##4;\ IMPLEMENT_SHADER_TYPE4_WITH_TEMPLATE_PREFIX(template<>, RENDERCORE_API, FCopyTextureCS_##SrcType##_##DstType##_##ValueType##4, SF_Compute); #define IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(SrcType,DstType)\ IMPLEMENT_COPY_RESOURCE_SHADER(SrcType,DstType,Float)\ IMPLEMENT_COPY_RESOURCE_SHADER(SrcType,DstType,Int32)\ IMPLEMENT_COPY_RESOURCE_SHADER(SrcType,DstType,Uint32) IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture2D , Texture2D ); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture2D , Texture2DArray); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture2D , Texture3D ); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture2DArray, Texture2D ); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture2DArray, Texture2DArray); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture2DArray, Texture3D ); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture3D , Texture2D ); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture3D , Texture2DArray); IMPLEMENT_COPY_RESOURCE_SHADER_ALL_TYPES(Texture3D , Texture3D ); ```

생성자는 다음과 같습니다.

  ... 클래스 선언 ...
protected:
  FCopyTextureCS() {}
  FCopyTextureCS(const ShaderMetaType::CompiledShaderInitializerType& Initializer)
      : FGlobalShader(Initializer)
  {
      DstOffsetParam.Bind(Initializer.ParameterMap, TEXT("DstOffset"), SPF_Mandatory);
      SrcOffsetParam.Bind(Initializer.ParameterMap, TEXT("SrcOffset"), SPF_Mandatory);
      DimensionsParam.Bind(Initializer.ParameterMap, TEXT("Dimensions"), SPF_Mandatory);
      SrcResourceParam.Bind(Initializer.ParameterMap, TEXT("SrcResource"), SPF_Mandatory);
      DstResourceParam.Bind(Initializer.ParameterMap, TEXT("DstResource"), SPF_Mandatory);
  }

Initializer를 보면 Parameter를 바인드 하는 것을 알 수 있습니다.
- Parameter는 FCopyTextureCS아래에 Protected로 정의되어 있습니다.

	... 클래스 선언 ...
public:
	inline const FShaderResourceParameter& GetSrcResourceParam() { return SrcResourceParam; }
	inline const FShaderResourceParameter& GetDstResourceParam() { return DstResourceParam; }

Dispatch를 정의했습니다.

  void Dispatch(
      FRHIComputeCommandList& RHICmdList,
      const CopyTextureCS::DispatchContext& Context,
      FIntVector const& SrcOffset,
      FIntVector const& DstOffset,
      FIntVector const& Dimensions
  )
  {
      check(SrcOffset.GetMin() >= 0 && DstOffset.GetMin() >= 0 && Dimensions.GetMin() >= 0);
      check(Context.DstType != ECopyTextureResourceType::Texture2D || Dimensions.Z <= 1);

      FRHIComputeShader* ShaderRHI = RHICmdList.GetBoundComputeShader();
      SetShaderValue(RHICmdList, ShaderRHI, SrcOffsetParam, SrcOffset);
      SetShaderValue(RHICmdList, ShaderRHI, DstOffsetParam, DstOffset);
      SetShaderValue(RHICmdList, ShaderRHI, DimensionsParam, Dimensions);

      RHICmdList.DispatchComputeShader(
          FMath::DivideAndRoundUp(uint32(Dimensions.X), Context.ThreadGroupSizeX),
          FMath::DivideAndRoundUp(uint32(Dimensions.Y), Context.ThreadGroupSizeY),
          FMath::DivideAndRoundUp(uint32(Dimensions.Z), Context.ThreadGroupSizeZ)
      );
  }

SetShaderValue는 D:\Program Files\Epic Games\UE_5.0\Engine\Source\Runtime\RenderCore\Public\ShaderParameterUtils.h에 정의되어 있습니다.
- 템플릿의 세이더 유형에 대해서 매개변수의 값을 설정합니다.
- 그 외에 유용한 유틸들이 많습니다.

Code

```cpp template<typename ShaderRHIParamRef, class ParameterType, typename TRHICmdList> void SetShaderValue( TRHICmdList& RHICmdList, const ShaderRHIParamRef& Shader, const FShaderParameter& Parameter, const ParameterType& Value, uint32 ElementIndex = 0 ) { static_assert(!TIsPointer::Value, "Passing by value is not valid."); const uint32 AlignedTypeSize = (uint32)Align(sizeof(ParameterType), SHADER_PARAMETER_ARRAY_ELEMENT_ALIGNMENT); const int32 NumBytesToSet = FMath::Min(sizeof(ParameterType),Parameter.GetNumBytes() - ElementIndex * AlignedTypeSize); // This will trigger if the parameter was not serialized checkSlow(Parameter.IsInitialized()); if(NumBytesToSet > 0) { RHICmdList.SetShaderParameter( Shader, Parameter.GetBufferIndex(), Parameter.GetBaseIndex() + ElementIndex * AlignedTypeSize, (uint32)NumBytesToSet, &Value ); } } ``` </detail> * 어떤 쉐이더를 이용할지에 대해 템플릿으로 구현되어 있습니다. ```cpp static inline TShaderRef SelectShader(FGlobalShaderMap* GlobalShaderMap, ECopyTextureResourceType SrcType, ECopyTextureResourceType DstType, ECopyTextureValueType ValueType, CopyTextureCS::DispatchContext& OutContext); protected: template static inline TShaderRef SelectShader(FGlobalShaderMap* GlobalShaderMap, CopyTextureCS::DispatchContext& OutContext); template static inline TShaderRef SelectShader(FGlobalShaderMap* GlobalShaderMap, ECopyTextureResourceType DstType, ECopyTextureValueType ValueType, CopyTextureCS::DispatchContext& OutContext); template <ECopyTextureResourceType SrcType, ECopyTextureResourceType DstType> static inline TShaderRef SelectShader(FGlobalShaderMap* GlobalShaderMap, ECopyTextureValueType ValueType, CopyTextureCS::DispatchContext& OutContext); ```

하단에 정의되어 있습니다.

```cpp template inline TShaderRef FCopyTextureCS::SelectShader(FGlobalShaderMap* GlobalShaderMap, CopyTextureCS::DispatchContext& OutContext) { TShaderRef Shader = GlobalShaderMap->GetShader(); Shader->GetDispatchContext(OutContext); return Shader; } template <ECopyTextureResourceType SrcType, ECopyTextureResourceType DstType> inline TShaderRef FCopyTextureCS::SelectShader(FGlobalShaderMap* GlobalShaderMap, ECopyTextureValueType ValueType, CopyTextureCS::DispatchContext& OutContext) { switch (ValueType) { default: checkNoEntry(); case ECopyTextureValueType::Float: return SelectShader<TCopyResourceCS<SrcType, DstType, ECopyTextureValueType::Float, 4>>(GlobalShaderMap, OutContext); case ECopyTextureValueType::Int32: return SelectShader<TCopyResourceCS<SrcType, DstType, ECopyTextureValueType::Int32, 4>>(GlobalShaderMap, OutContext); case ECopyTextureValueType::Uint32: return SelectShader<TCopyResourceCS<SrcType, DstType, ECopyTextureValueType::Uint32, 4>>(GlobalShaderMap, OutContext); } } template inline TShaderRef FCopyTextureCS::SelectShader(FGlobalShaderMap* GlobalShaderMap, ECopyTextureResourceType DstType, ECopyTextureValueType ValueType, CopyTextureCS::DispatchContext& OutContext) { switch (DstType) { default: checkNoEntry(); case ECopyTextureResourceType::Texture2D: return FCopyTextureCS::SelectShader<SrcType, ECopyTextureResourceType::Texture2D >(GlobalShaderMap, ValueType, OutContext); case ECopyTextureResourceType::Texture2DArray: return FCopyTextureCS::SelectShader<SrcType, ECopyTextureResourceType::Texture2DArray>(GlobalShaderMap, ValueType, OutContext); case ECopyTextureResourceType::Texture3D: return FCopyTextureCS::SelectShader<SrcType, ECopyTextureResourceType::Texture3D >(GlobalShaderMap, ValueType, OutContext); } } inline TShaderRef FCopyTextureCS::SelectShader(FGlobalShaderMap* GlobalShaderMap, ECopyTextureResourceType SrcType, ECopyTextureResourceType DstType, ECopyTextureValueType ValueType, CopyTextureCS::DispatchContext& OutContext) { switch (SrcType) { default: checkNoEntry(); case ECopyTextureResourceType::Texture2D: return FCopyTextureCS::SelectShader<ECopyTextureResourceType::Texture2D >(GlobalShaderMap, DstType, ValueType, OutContext); case ECopyTextureResourceType::Texture2DArray: return FCopyTextureCS::SelectShader<ECopyTextureResourceType::Texture2DArray>(GlobalShaderMap, DstType, ValueType, OutContext); case ECopyTextureResourceType::Texture3D: return FCopyTextureCS::SelectShader<ECopyTextureResourceType::Texture3D >(GlobalShaderMap, DstType, ValueType, OutContext); } } ``` </detail> * 변수로 사용할 파라메터를 정의하는 부분입니다. ```cpp ... 클래스 선언 ... LAYOUT_FIELD(FShaderParameter, DstOffsetParam); LAYOUT_FIELD(FShaderParameter, SrcOffsetParam); LAYOUT_FIELD(FShaderParameter, DimensionsParam); LAYOUT_FIELD(FShaderResourceParameter, SrcResourceParam); LAYOUT_FIELD(FShaderResourceParameter, DstResourceParam); }; ``` * 이부분은 제대로 찾은건지 모르겠습니다. CopyTextureShader.usf입니다.

.usf파일

```cpp // Copyright Epic Games, Inc. All Rights Reserved. /*============================================================================= CopyTextureShaders.usf: Generic shader for copying 2D, 2D Array and 3D texture resources =============================================================================*/ #include "Common.ush" uint3 DstOffset; // Front upper left texel in the destination texture to start writing data to uint3 SrcOffset; // Front upper left texel in the source texture to start reading data from uint3 Dimensions; // The total x,y,z number of texels in the copy region #if SRC_TYPE == 0 Texture2D SrcResource; #define SRC_ADDR(p,o) ((p).xy + (o).xy) #elif SRC_TYPE == 1 Texture2DArray SrcResource; #define SRC_ADDR(p,o) ((p).xyz + (o).xyz) #elif SRC_TYPE == 2 Texture3D SrcResource; #define SRC_ADDR(p,o) ((p).xyz + (o).xyz) #endif #if DST_TYPE == 0 RWTexture2D DstResource; #define DST_ADDR(p,o) ((p).xy + (o).xy) #elif DST_TYPE == 1 RWTexture2DArray DstResource; #define DST_ADDR(p,o) ((p).xyz + (o).xyz) #elif DST_TYPE == 2 RWTexture3D DstResource; #define DST_ADDR(p,o) ((p).xyz + (o).xyz) #endif #define COMP(a,b) (((a).x < (b).x) && ((a).y < (b).y) && ((a).z < (b).z)) [numthreads(THREADGROUPSIZE_X, THREADGROUPSIZE_Y, THREADGROUPSIZE_Z)] void CopyTextureCS(uint3 Position : SV_DispatchThreadID) { if (COMP(Position, Dimensions)) { DstResource[DST_ADDR(Position, DstOffset)] = SrcResource[SRC_ADDR(Position, SrcOffset)]; } } ``` </detail>