OpenXR - Gran Turismo camera shaking workaround

[lvonasek]

Since #18438 there is VR camera shaking in Gran Turismo. This PR fixes that on all headsets.

[hrydgard]

The shaking thing in GT is a type of temporal antialiasing using the slowness of the PSP's LCD. It of course works very badly at higher screen resolutions.

It can actually be turned-off in-game with a setting: External video output.

So having a code workaround for it feels a bit excessive - though, I guess it's also awkward to have to tell the player to use this option, and we currently don't have a good way to do it..

[lvonasek]

Interesting. I wouldn't expect the shaking is an intention. I leave it on you but I find pity that the best looking PSP game don't work out of the box (even that it worked in the previous version). The new compat flag is basically switching between an old projection matrix Hack and new projection matrix hack.

[hrydgard]

How did it work in VR previously?

[lvonasek]

It used the projection matrix from OpenXR and changed the signs of all 16 values to match the signs of the game projection matrix. That for some reason is very broken on Quest3.

[lvonasek]

I am closing this. Let's keep the VR integration simple.