Hi, First, I create a rendertaget for offscreen rendering, i.e. IDirect3DTexture9* pTexture; IDirect3DSurface9* pSurface_BackBuffer; IDirect3DSurface9* pSurface_Render; width = 256; height = 256; Levels = 1; Usage = D3DUSAGE_RENDERTARGET; Format= D3DFMT_A32B32G32R32F; Pool = D3DPOOL_DEFAULT; pSharedHandle = 0; device->CreateTexture(Width, Height, Levels, Usage, Format, Pool, &pTexture, pSharedHandle); ... Then, do rendering like this ID3DXEffect *effect; // assume initialized g_Device->GetRenderTarget(0,&pSurface_BackBuffer); pTexture->GetSurfaceLevel(0,&pSurface_Render); g_Device->SetRenderTarget(0,pSurface_Render); g_Device->BeginScene(); UINT n; effect->Begin(&n, 0); effect->BeginPass(0); // render something effect->EndPass(); effect->End(); g_Device->SetRenderTarget(0,pSurface_BackBuffer); And then, do the normal rendering. If I do it in this way, is it doing offscreen rendering of render target? If not, what functions do I need to call for offscreen rendering of render target? Thank you. Jacky