[SDL] Fast alpha blitting

Tyler Montbriand tsm at accesscomm.ca
Fri Sep 16 09:08:37 PDT 2005

On September 16, 2005 03:23 am, Mathew Byrne wrote:
> Hi,
> Just working on a small test program at the moment and performance is
> rapidly
> deteriorating as the size increases. Removing alpha blended images just
> about
> doubles the performance, but I'd really prefer to keep them in the
> application.
> Just wondering if there are any particularaly fast methods of using image
> alpha channels? I've searched around a bit but there doesn't seem to be any
> good tutorials/guides on alpha channels and SDL.
It is VERY HARD to get fast 2D alpha-channel blits; very few things except 
OpenGL can support it in hardware.  Note that SDL has a faster special-case 
alpha blitter for alpha=128.

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