A variable that decides what video backend to use.
Defined in SDL_hints.h
#define SDL_HINT_VIDEODRIVER "SDL_VIDEODRIVER"By default, SDL will try all available video backends in a reasonable order until it finds one that can work, but this hint allows the app or user to force a specific target, such as "x11" if, say, you are on Wayland but want to try talking to the X server instead.
This functionality has existed since SDL 2.0.0 (indeed, before that) but before 2.0.22 this was an environment variable only. In 2.0.22, it was upgraded to a full SDL hint, so you can set the environment variable as usual or programatically set the hint with SDL_SetHint, which won't propagate to child processes.
The default value is unset, in which case SDL will try to figure out the best video backend on your behalf. This hint needs to be set before SDL_Init() is called to be useful.
This hint is available since SDL 2.0.22. Before then, you could set the environment variable to get the same effect.