Convert Scene Depth Texture to FLOAT Texture

Development Programming & Scripting C++
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Hi, there. I need to get the scene depth values, and share through cuda interp to do some post processing.

And I found that cudaGraphicsD3D11RegisterResource dont support depth or stencil , Surfaces of depth or stencil formats cannot be shared says in the document, howerver DXGI_FORMAT_R32_FLOAT is supported.

So my question is:

Is it posible to convert a Depth Texture (returned from GetSceneDepthTexture()) to a PF_R32_FLOAT format Texture?

I tried with the following code, but got 0 values all the time.

FIntPoint TextureSize;
float* cpuDataPtr;	// Texture深度值数组首地址
TArray<float> mydata;	//最终获取色深度值数据

ENQUEUE_RENDER_COMMAND(NeRFGenRHITexureToCUDA)(
	[=, _this = this, &TextureSize](FRHICommandListImmediate& RHICmdList) mutable {
		FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, 1);
		FTexture2DRHIRef RHITexture2D = FSceneRenderTargets::Get(RHICmdList).GetSceneDepthSurface();

		if (_this->SceneDepthDevice != nullptr)
		{
			CUDA_CHECK_LOG(
				cudaFree(_this->SceneDepthDevice)
			);
		}

		CUDA_CHECK_LOG(
			cudaMallocPitch(
				&_this->SceneDepthDevice,
				&_this->SceneDepthDevicePitch,
				RHITexture2D->GetSizeX() * 1 * sizeof(float),
				RHITexture2D->GetSizeY())
		);

		if (frame_no == 0)
		{
			UE_LOG(LogNeRF, Log, TEXT("RenderResolution: %f, %f"), RHITexture2D->GetSizeX(), RHITexture2D->GetSizeY());
		}

		TextureSize = RHITexture2D->GetSizeXY();

		FRHIResourceCreateInfo CreateInfo;
		FTexture2DRHIRef DepthFloatTexture = RHICmdList.CreateTexture2D(
			TextureSize.X,
			TextureSize.Y,
			PF_R32_FLOAT,
			1, 1,
			TexCreate_RenderTargetable | TexCreate_ShaderResource,
			CreateInfo);

		FResolveParams ResolveParams;
		//ResolveParams.CubeFace = ECubeFace::CubeFace_MAX;
		//ResolveParams.Rect = FResolveRect(0, 0, TextureSize.X, TextureSize.Y);
		//ResolveParams.DestRect = ResolveParams.Rect;
		//ResolveParams.MipIndex = 0;
		//ResolveParams.SourceArrayIndex = 0;
		//ResolveParams.DestArrayIndex = 0;


		RHICmdList.CopyToResolveTarget(RHITexture2D, DepthFloatTexture, ResolveParams);

		mydata.AddUninitialized(TextureSize.X * TextureSize.Y);
		uint32 Lolstrid = 0;
		cpuDataPtr = (float*)RHILockTexture2D(DepthFloatTexture, 0, RLM_ReadOnly, Lolstrid, true);	// 加锁 获取可读depth Texture深度值数组首地址
		memcpy(mydata.GetData(), cpuDataPtr, TextureSize.X * TextureSize.Y * sizeof(float));		//复制深度数据
		RHIUnlockTexture2D(DepthFloatTexture, 0, true);	//解锁

		if (!_this->RHICudaBridge.has_init())
		{
			res = _this->RHICudaBridge.init_resource(
				DepthFloatTexture,
				RHICmdList,
				DXGI_FORMAT_R32_FLOAT,
				D3D11_BIND_SHADER_RESOURCE
			);
			if (!res)
			{
				UE_LOG(LogNeRF, Error, TEXT("Initialize RHICudaBridge FAILED"));
				return;
			}
		}

		_this->RHICudaBridge.execute_from(
			_this->SceneDepthDevice,
			DepthFloatTexture,
			DepthFloatTexture->GetSizeX(),
			DepthFloatTexture->GetSizeY(),
			//ViewportSize.X,
			//ViewportSize.Y,
			1,
			_this->SceneDepthDevicePitch,
			sizeof(float),
			nullptr);



		FSceneRenderTargets::Get(RHICmdList).AdjustGBufferRefCount(RHICmdList, -1);
	});

FlushRenderingCommands();	//等待渲染线程执行

IImageWrapperModule& ImageWrapperModule = FModuleManager::LoadModuleChecked<IImageWrapperModule>(FName("ImageWrapper"));
static TSharedPtr<IImageWrapper> imageWrapper = ImageWrapperModule.CreateImageWrapper(EImageFormat::EXR); //EImageFormat::PNG //EImageFormat::JPEG
imageWrapper->SetRaw(mydata.GetData(), mydata.GetAllocatedSize(), TextureSize.X, TextureSize.Y, ERGBFormat::Gray, 32);
const TArray64<uint8>& PngData = imageWrapper->GetCompressed(0);
FFileHelper::SaveArrayToFile(PngData, TEXT("depth.exr"));