[SDL] Optimal mode from SDL_GetVideoMode

[benang at cs.its.ac.id]

>
>> Thanks for the feedback. It's very enlightening. Just as I thought,
>> using
>> X will make the game runs slower.
>
> Not necessarily: if there's an X driver for the video chip (verses the
> fbcon "vesa" driver, for example) it may be quite a bit faster...but on
> an embedded system it'll take a lot more memory to run an X server.
> There may be a little more overhead involved in X11, but I wouldn't
> imagine it to be significant beyond memory requirements. It's all a
> matter of what you have and what you need, so I wanted to throw the idea
> out there.
>
> Generally using fbcon requires the kernel to support it, and SDL to be
> built with support for it. Do this last, since all the other details of
> your program that you can do in X will apply to it when using fbcon. In
> fact, you shouldn't even need to recompile the program to switch video
> targets.
>
> The biggest optimization win will probably be a dirty rectangle
> algorithm, if you don't have to paint the whole screen every frame. The
> easiest win is to preconvert all your surfaces to the screen format with
> SDL_DisplayFormat() and disabling alpha blending in favor of colorkey
> blits, if you aren't already.
>
> --ryan.
>

Okay. Will do that for now. Maybe I should've examined Sam's alien example
back then. :(