[SDL] Double buffering in windowed and fullscreen modes

Pete Shinners pete at visionart.com
Fri Aug 31 11:01:01 PDT 2001


>>No hardware acceleration for windowed surfaces?  Will this be fixed in
>>SDL1.3?
>>
> 
> AFAIK, no. Windows doesn't support it - and cannot, without hardware 
> based clipping. DirectX allows you to blit to the "screen" surface of a 
> window and does clipping internally, but if you were allowed to lock the 
> surface and access VRAM directly, you'd have to deal with clipping 
> yourself not to overdraw other windows, mouse pointer (unless it's a 
> hardware sprite), menues etc.

actually, with directx you get great hardware support
for windows. this shouldn't be too surprising, after all
you can also get accelerated and doublebuffered opengl
windows.

directdraw does provide you with hardware clipping controls,
when you create a hardware accelerated directx window, you
also create a hardware clipper, that you let windows
control for you. if you don't create that clipper you
overwrite other windows on the screen. since you let windows
take control of the clipper, you really don't need to mess
with it, although it looks like you can if you want to do
your own special clipping.

i've always thought the reason there was no support for
hardware acceleration for windows was you run into more
frequent problems with windows "losing" your surfaces?
but i've never really been sure.





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