Begins a scene.
This method has no parameters.
If the method succeeds, the return value is D3D_OK. The method will fail with D3DERR_INVALIDCALL if IDirect3DDevice9::BeginScene is called while already in a IDirect3DDevice9::BeginScene/IDirect3DDevice9::EndScene pair. This happens only when IDirect3DDevice9::BeginScene is called twice without first calling IDirect3DDevice9::EndScene.
Applications must call IDirect3DDevice9::BeginScene before performing any rendering and must call IDirect3DDevice9::EndScene when rendering is complete and before calling IDirect3DDevice9::BeginScene again.
If IDirect3DDevice9::BeginScene fails, the device was unable to begin the scene, and there is no need to call IDirect3DDevice9::EndScene. In fact, calls to IDirect3DDevice9::EndScene will fail if the previous IDirect3DDevice9::BeginScene failed. This applies to any application that creates multiple swap chains.
There should be one IDirect3DDevice9::BeginScene/IDirect3DDevice9::EndScene pair between any successive calls to present (either IDirect3DDevice9::Present or IDirect3DSwapChain9::Present). IDirect3DDevice9::BeginScene should be called once before any rendering is performed, and IDirect3DDevice9::EndScene should be called once after all rendering for a frame has been submitted to the runtime. Multiple non-nested IDirect3DDevice9::BeginScene/IDirect3DDevice9::EndScene pairs between calls to present are legal, but having more than one pair may incur a performance hit. To enable maximal parallelism between the CPU and the graphics accelerator, it is advantageous to call IDirect3DDevice9::EndScene as far ahead of calling present as possible.
Build date: 11/16/2013