[SDL] How to choose videodrivers on windows

[Ilya Olevsky]

> Is this the best way to ask sdl to test first for directx, then  
> for the other available drivers? (I just know about windib)

As far as I know, SDL will figure out what to use if DirectX fails (all 
the way down to GDI) so this should be enough:

#ifdef WIN32
	SDL_putenv("SDL_VIDEODRIVER=directx");
#endif

I don't think you need to worry much about it. It's doubtful that there 
are any working Windows boxes these days that don't have some version of 
DirectX installed.