[SDL] refreshing my knowledge
Roger D. Vargas
roger at eht.scu.tur.cu
Mon Jan 13 05:51:01 PST 2003
On Sun, 12 Jan 2003, José Luis Sánchez wrote:
> "Roger D. Vargas" <roger at eht.scu.tur.cu> escribió:
> > I would like to confirm some things about blits:
> > video ram to video ram blits are faster
> > writing directly to vram (ie. modifying pixels) is very slow.
> > system ram to video ram blits are a bit slower
> > There is some difference if there is support for accelerated blits?
> The scenario is actually somewhat more complex.
I know, but the idea is to give some "quick guides" about blitting.
> Note that the GPU might be actually SLOWER than the main CPU. In fact, the
> FASTEST blits are from system RAM to system RAM. Just remember: the
goal is to
> use CPU cycles as little as possible.
So, we can consider that if we have to do a lot of blits, we better put
the surface in the system memory and blit the final result to vram?
Another question, where is located the surface returned by SetVideoMode?
> Loudly, those cycles are wasted if you simply keep your CPU waiting for the
> blit to be completed. So you might design your program so that it does
> actually something useful while the GPU is busy.
And how can I do this? How can i process something while Im blitting?
Roger D. Vargas | El sistema se apagara en 5 segundos.
ICQ: 117641572 | Salvese el que pueda!
Linux User: 180787 |
More information about the SDL