RFC: wined3d: Check for and use FBO blits early in BltOverride

[Stefan Dösinger]

On Sunday 27 March 2011 06:26:47 Chris Robinson wrote:
> After some testing and talking with Henri, it seems a number of checks
> aren't needed if FBO blits are available, particularly the
> swapchain/active render target checks. The attached patch makes
> BltOverride check for FBO blits earlier, which helps it catch more cases
> where blits can be accelerated. It provides a significant improvement with
> the aforementioned programs.
BltOverride is a horrible mess, and I'm afraid the patch doesn't make it any 
better. A long time ago Roderick started a cleanup to give the blit selection 
routine a more structured approach, but he never finished the work. 
Unfortunately a proper fix is not a weekend task :-(

Besides simple unconverted blits we should also be able to do converted blits 
via FBOs + shader draws, e.g. to blit a YUV surface to an offscreen render 
target. This is needed for HW accelerated video playback with quicktime. And I 
am sure there are many other things that need to be considered.