DirectX: Game loop order, draw first and then handle input?
- by Ricket
I was just reading through the DirectX documentation and encountered something interesting in the page for IDirect3DDevice9::BeginScene :
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.
I've been accustomed to writing my game loop to handle input and such, then draw. Do I have it backwards? Maybe the game loop should be more like this: (semi-pseudocode, obviously)
while(running) {
d3ddev->Clear(...);
d3ddev->BeginScene();
// draw things
d3ddev->EndScene();
// handle input
// do any other processing
// play sounds, etc.
d3ddev->Present(NULL, NULL, NULL, NULL);
}
According to that sentence of the documentation, this loop would "enable maximal parallelism".
Is this commonly done? Are there any downsides to ordering the game loop like this? I see no real problem with it after the first iteration... And I know the best way to know the actual speed increase of something like this is to actually benchmark it, but has anyone else already tried this and can you attest to any actual speed increase?
