GPU: Add setting to control inflight frame usage

[unknownbrackets]

So that users can turn it off and be sure it's not a source of input lag.

Not super confident about the checkbox title, "Allow gameplay ahead of display (faster, input lag)", open to competing ideas...

-[Unknown]

[hrydgard]

"Buffering" or "Queue" can indicate a cause of latency - maybe "graphics command buffering" or "max queued frames" or something? Hm..

[unknownbrackets]

I've changed it to "Buffer graphics commands (faster, input lag)". I think it makes sense...

-[Unknown]

[hrydgard]

Yeah, that's OK.

Hm, I'm wondering if it's interesting to allow a value of 2 as well? Might be useful as a compromise. Just figure thinking about this before we lock down the translation string...

[unknownbrackets]

Okay, added that. Used "Up to 2" to try to make it clear that it's not fixed at that.

-[Unknown]

[iota97]

On Linux at least changing this in game cause all sort of problem (Missing tris, flicker, weird frame in between, emulator become unresponsive and need to be killed). It can even cause problem if you go in game, exit to main menu, change it and start another game (didn't manage to see any of them if changed before starting a game at all).

May be better to disable in game (and may require a restart like graphical API change)?

[unknownbrackets]

Hm, I hadn't reproduced that before but I'm seeing it now. Ideally, we should restart graphics (similar to when you resize on Android), but this will only work on some platforms. For example, Windows / OpenGL doesn't really have a way to restart graphics... we may have to restart indeed.

-[Unknown]