CustomStencilSRV创建过程

怼烎@ 2022-10-15 10:57 142阅读 0赞

1. F:\\UnrealEngine-424\\Engine\\Source\\Runtime\\Renderer\\Private\\PostProcess\\SceneRenderTargets.cpp

IPooledRenderTarget* FSceneRenderTargets::RequestCustomDepth(FRHICommandListImmediate& RHICmdList, bool bPrimitives)
    {
    	int Value = CVarCustomDepth.GetValueOnRenderThread();
    	const bool bCustomDepthPassWritingStencil = IsCustomDepthPassWritingStencil();
    	const bool bMobilePath = (CurrentFeatureLevel <= ERHIFeatureLevel::ES3_1);
    
    	if ((Value == 1 && bPrimitives) || Value == 2 || bCustomDepthPassWritingStencil)
    	{
    		bool bHasValidCustomDepth = (CustomDepth.IsValid() && BufferSize == CustomDepth->GetDesc().Extent && !GFastVRamConfig.bDirty);
    		bool bHasValidCustomStencil;
    		if (bMobilePath)
    		{
    			bHasValidCustomStencil = (MobileCustomStencil.IsValid() && BufferSize == MobileCustomStencil->GetDesc().Extent);
    		}
    		else
    		{
    			bHasValidCustomStencil = CustomStencilSRV.IsValid();
    		}
    						
    		if (!(bHasValidCustomDepth && bHasValidCustomStencil))
    		{
    			// Skip depth decompression, custom depth doesn't benefit from it
    			// Also disables fast clears, but typically only a small portion of custom depth is written to anyway
    			uint32 CustomDepthFlags = TexCreate_NoFastClear;
    
    			// Todo: Could check if writes stencil here and create min viable target
    			FPooledRenderTargetDesc Desc(FPooledRenderTargetDesc::Create2DDesc(BufferSize, PF_DepthStencil, FClearValueBinding::DepthFar, CustomDepthFlags, TexCreate_DepthStencilTargetable | TexCreate_ShaderResource, false));
    			Desc.Flags |= GFastVRamConfig.CustomDepth;
    			GRenderTargetPool.FindFreeElement(RHICmdList, Desc, CustomDepth, TEXT("CustomDepth"), true, ERenderTargetTransience::NonTransient);
    			
    			if (bMobilePath)
    			{
    				FPooledRenderTargetDesc MobileCustomStencilDesc(FPooledRenderTargetDesc::Create2DDesc(BufferSize, PF_B8G8R8A8, FClearValueBinding::Transparent, TexCreate_None, TexCreate_RenderTargetable | TexCreate_ShaderResource, false));
    				GRenderTargetPool.FindFreeElement(RHICmdList, MobileCustomStencilDesc, MobileCustomStencil, TEXT("MobileCustomStencil"));
    			}
    			else
    			{
    				//CustomStencilSRV = RHICreateShaderResourceView((FTexture2DRHIRef&)CustomDepth->GetRenderTargetItem().TargetableTexture, 0, 1, PF_X24_G8);
    				CustomStencilSRV = RHICreateShaderResourceView((FTexture2DRHIRef&)CustomDepth->GetRenderTargetItem().TargetableTexture, 0, 1, PF_B8G8R8A8);
    			}
    		}
    		return CustomDepth;
    	}
    
    	return 0;
    }

2. RHICreateShaderResourceView() 在F:\\UnrealEngine-424\\Engine\\Source\\Runtime\\RHI\\Public\\RHICommandList.h

FORCEINLINE FShaderResourceViewRHIRef RHICreateShaderResourceView(FRHITexture* Texture, uint8 MipLevel, uint8 NumMipLevels, uint8 Format)
    {
    	return FRHICommandListExecutor::GetImmediateCommandList().CreateShaderResourceView(Texture, MipLevel, NumMipLevels, Format);
    }

3. 也在RHICommandList.h

FORCEINLINE FShaderResourceViewRHIRef CreateShaderResourceView(FRHITexture* Texture, uint8 MipLevel, uint8 NumMipLevels, uint8 Format)
    	{
    		LLM_SCOPE(ELLMTag::RHIMisc);
    		const FRHITextureSRVCreateInfo CreateInfo(MipLevel, NumMipLevels, Format);
    		return GDynamicRHI->RHICreateShaderResourceView_RenderThread(*this, Texture, CreateInfo);
    	}

4. 在RHICommandList.cpp 中

FShaderResourceViewRHIRef FDynamicRHI::RHICreateShaderResourceView_RenderThread(class FRHICommandListImmediate& RHICmdList, FRHITexture* Texture, const FRHITextureSRVCreateInfo& CreateInfo)
    {
    	CSV_SCOPED_TIMING_STAT(RHITStalls, RHICreateShaderResourceView_RenderThread_Tex2D); // TODO - clean this up
    	FScopedRHIThreadStaller StallRHIThread(RHICmdList);
    	return GDynamicRHI->RHICreateShaderResourceView(Texture, CreateInfo);
    }

5. 只考虑Windows平台，F:\\UnrealEngine-424\\Engine\\Source\\Runtime\\Windows\\D3D11RHI\\Private\\D3D11Texture.cpp

FShaderResourceViewRHIRef FD3D11DynamicRHI::RHICreateShaderResourceView(FRHITexture* TextureRHI, const FRHITextureSRVCreateInfo& CreateInfo)
    {
    	FD3D11TextureBase* Texture = GetD3D11TextureFromRHITexture(TextureRHI);
    
    	// Create a Shader Resource View
    	D3D11_SHADER_RESOURCE_VIEW_DESC SRVDesc;
    	DXGI_FORMAT BaseTextureFormat = DXGI_FORMAT_UNKNOWN;
    
    	if (TextureRHI->GetTexture3D() != NULL)
    	{
    		FD3D11Texture3D* Texture3D = static_cast<FD3D11Texture3D*>(Texture);
    
    		D3D11_TEXTURE3D_DESC TextureDesc;
    		Texture3D->GetResource()->GetDesc(&TextureDesc);
    		BaseTextureFormat = TextureDesc.Format;
    
    		SRVDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE3D;
    		SRVDesc.Texture3D.MostDetailedMip = CreateInfo.MipLevel;
    		SRVDesc.Texture3D.MipLevels = CreateInfo.NumMipLevels;
    	}
    	else if (TextureRHI->GetTexture2DArray() != NULL)
    	{
    		FD3D11Texture2DArray* Texture2DArray = static_cast<FD3D11Texture2DArray*>(Texture);
    
    		D3D11_TEXTURE2D_DESC TextureDesc;
    		Texture2DArray->GetResource()->GetDesc(&TextureDesc);
    		BaseTextureFormat = TextureDesc.Format;
    
    		SRVDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2DARRAY;
    		SRVDesc.Texture2DArray.MostDetailedMip = CreateInfo.MipLevel;
    		SRVDesc.Texture2DArray.MipLevels = CreateInfo.NumMipLevels;
    		SRVDesc.Texture2DArray.FirstArraySlice = CreateInfo.FirstArraySlice;
    		SRVDesc.Texture2DArray.ArraySize = (CreateInfo.NumArraySlices == 0 ? TextureDesc.ArraySize : CreateInfo.NumArraySlices);
    	}
    	else if (TextureRHI->GetTextureCube() != NULL)
    	{
    		FD3D11TextureCube* TextureCube = static_cast<FD3D11TextureCube*>(Texture);
    
    		D3D11_TEXTURE2D_DESC TextureDesc;
    		TextureCube->GetResource()->GetDesc(&TextureDesc);
    		BaseTextureFormat = TextureDesc.Format;
    
    		SRVDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURECUBE;
    		SRVDesc.TextureCube.MostDetailedMip = CreateInfo.MipLevel;
    		SRVDesc.TextureCube.MipLevels = CreateInfo.NumMipLevels;
    	}
    	else
    	{
    		FD3D11Texture2D* Texture2D = static_cast<FD3D11Texture2D*>(Texture);
    
    		D3D11_TEXTURE2D_DESC TextureDesc;
    		Texture2D->GetResource()->GetDesc(&TextureDesc);
    		BaseTextureFormat = TextureDesc.Format;
    
    		if (TextureDesc.SampleDesc.Count > 1)
    		{
    			///MS textures can't have mips apparently, so nothing else to set.
    			SRVDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2DMS;
    		}
    		else
    		{
    			SRVDesc.ViewDimension = D3D11_SRV_DIMENSION_TEXTURE2D;
    			SRVDesc.Texture2D.MostDetailedMip = CreateInfo.MipLevel;
    			SRVDesc.Texture2D.MipLevels = CreateInfo.NumMipLevels;
    		}
    	}
    
    	// Allow input CreateInfo to override SRGB and/or format
    	const bool bBaseSRGB = (TextureRHI->GetFlags() & TexCreate_SRGB) != 0;
    	const bool bSRGB = (CreateInfo.SRGBOverride == SRGBO_ForceEnable) || (CreateInfo.SRGBOverride == SRGBO_Default && bBaseSRGB);
    	if (CreateInfo.Format != PF_Unknown)
    	{
    		BaseTextureFormat = (DXGI_FORMAT)GPixelFormats[CreateInfo.Format].PlatformFormat;
    	}
    	SRVDesc.Format = FindShaderResourceDXGIFormat(BaseTextureFormat, bSRGB);
    
    	// Create a Shader Resource View
    	TRefCountPtr<ID3D11ShaderResourceView> ShaderResourceView;
    	VERIFYD3D11RESULT_EX(Direct3DDevice->CreateShaderResourceView(Texture->GetResource(), &SRVDesc, (ID3D11ShaderResourceView**)ShaderResourceView.GetInitReference()), Direct3DDevice);
    
    	return new FD3D11ShaderResourceView(ShaderResourceView, Texture);
    }

5.1 D3D11.h

typedef struct D3D11_TEXTURE2D_DESC
        {
        UINT Width;
        UINT Height;
        UINT MipLevels;
        UINT ArraySize;
        DXGI_FORMAT Format;
        DXGI_SAMPLE_DESC SampleDesc;
        D3D11_USAGE Usage;
        UINT BindFlags;
        UINT CPUAccessFlags;
        UINT MiscFlags;
        } 	D3D11_TEXTURE2D_DESC;

5.2 D3D11Resources.h

/** Given a pointer to a RHI texture that was created by the D3D11 RHI, returns a pointer to the FD3D11TextureBase it encapsulates. */
    FORCEINLINE FD3D11TextureBase* GetD3D11TextureFromRHITexture(FRHITexture* Texture)
    {
    	if (!Texture)
    	{
    		return NULL;
    	}
    	FD3D11TextureBase* Result((FD3D11TextureBase*)Texture->GetTextureBaseRHI());
    	check(Result);
    	return Result;
    }

5.3 在D3D11Resources.h

/** Shader resource view class. */
    class FD3D11ShaderResourceView : public FRHIShaderResourceView
    {
    public:
    	
    	TRefCountPtr<ID3D11ShaderResourceView> View;
    	TRefCountPtr<FD3D11BaseShaderResource> Resource;
    
    	FD3D11ShaderResourceView(ID3D11ShaderResourceView* InView,FD3D11BaseShaderResource* InResource)
    	: View(InView)
    	, Resource(InResource)
    	{}
    
    	void Rename(ID3D11ShaderResourceView* InView, FD3D11BaseShaderResource* InResource)
    	{
    		View = InView;
    		Resource = InResource;
    	}
    };

5.4 FindShaderResourceDXGIFormat(BaseTextureFormat, bSRGB) 在D3D11RHIPrimitive.h

/** Find an appropriate DXGI format for the input format and SRGB setting. */
    inline DXGI_FORMAT FindShaderResourceDXGIFormat(DXGI_FORMAT InFormat,bool bSRGB)
    {
    	if(bSRGB)
    	{
    		switch(InFormat)
    		{
    		case DXGI_FORMAT_B8G8R8A8_TYPELESS:    return DXGI_FORMAT_B8G8R8A8_UNORM_SRGB;
    		case DXGI_FORMAT_R8G8B8A8_TYPELESS:    return DXGI_FORMAT_R8G8B8A8_UNORM_SRGB;
    		case DXGI_FORMAT_BC1_TYPELESS:         return DXGI_FORMAT_BC1_UNORM_SRGB;
    		case DXGI_FORMAT_BC2_TYPELESS:         return DXGI_FORMAT_BC2_UNORM_SRGB;
    		case DXGI_FORMAT_BC3_TYPELESS:         return DXGI_FORMAT_BC3_UNORM_SRGB;
    		case DXGI_FORMAT_BC7_TYPELESS:         return DXGI_FORMAT_BC7_UNORM_SRGB;
    		};
    	}
    	else
    	{
    		switch(InFormat)
    		{
    		case DXGI_FORMAT_B8G8R8A8_TYPELESS: return DXGI_FORMAT_B8G8R8A8_UNORM;
    		case DXGI_FORMAT_R8G8B8A8_TYPELESS: return DXGI_FORMAT_R8G8B8A8_UNORM;
    		case DXGI_FORMAT_BC1_TYPELESS:      return DXGI_FORMAT_BC1_UNORM;
    		case DXGI_FORMAT_BC2_TYPELESS:      return DXGI_FORMAT_BC2_UNORM;
    		case DXGI_FORMAT_BC3_TYPELESS:      return DXGI_FORMAT_BC3_UNORM;
    		case DXGI_FORMAT_BC7_TYPELESS:      return DXGI_FORMAT_BC7_UNORM;
    		};
    	}
    	switch(InFormat)
    	{
    		case DXGI_FORMAT_R24G8_TYPELESS: return DXGI_FORMAT_R24_UNORM_X8_TYPELESS;
    		case DXGI_FORMAT_R32_TYPELESS: return DXGI_FORMAT_R32_FLOAT;
    		case DXGI_FORMAT_R16_TYPELESS: return DXGI_FORMAT_R16_UNORM;
    		// Changing Depth Buffers to 32 bit on Dingo as D24S8 is actually implemented as a 32 bit buffer in the hardware
    		case DXGI_FORMAT_R32G8X24_TYPELESS: return DXGI_FORMAT_R32_FLOAT_X8X24_TYPELESS; 
    	}
    	return InFormat;
    }

5.5 VERIFYD3D11RESULT\_EX(Direct3DDevice->CreateShaderResourceView(Texture->GetResource(), &SRVDesc, (ID3D11ShaderResourceView\*\*)ShaderResourceView.GetInitReference()), Direct3DDevice);