Hi,

I am trying to readback a volume texture into sysmem to be able to save it to file of my own format. I have to use DirectX 9. Some code:

--
IDirect3DVolumeTexture9 *sysTexture    = 0;
IDirect3DVolumeTexture9 *inputTexture  = 0;
IDirect3DVolumeTexture9 *outputTexture  = 0;

HRESULT hr;
hr = D3DXCreateVolumeTexture(pDevice, sizeX, sizeY, sizeZ, 1, 0, D3DFMT_A8, D3DPOOL_SYSTEMMEM, &sysTexture);
hr = D3DXCreateVolumeTexture(pDevice, sizeX, sizeY, sizeZ, 1, 0, D3DFMT_A8, D3DPOOL_DEFAULT, &inputTexture);
hr = D3DXCreateVolumeTexture(pDevice, sizeX, sizeY, sizeZ, 1, 0, D3DFMT_A8, D3DPOOL_DEFAULT, &outputTexture);

// Upload texture
LoadMyVolumeToSysTexture(sysTexture, (unsigned char *)pData, sizeX, sizeY, sizeZ);
hr = pDevice->UpdateTexture(sysTexture, inputTexture);

MyOwnProcessing(inputTexture, outputTexture);
--

Now, does anyone know how I can readback outputTexture to the CPU again? Any help would be highly appreciated. I have looked around in the forums for quite some time now without success. I see that people are using GetRenderTargetData(), but isn't that function only for 2D?

Best regards,
Andy

You use GetRenderTargetData to get data from a render target created by the GPU into the CPU.

You use UpdateTexture to get data from the CPU into the GPU.

You can't render to a volume texture in D3D9, so the only way that data gets into a volume texture in D3D9 is for you to put it there from the CPU.  Since you put it there, you already have a copy on the CPU.