Configurable VR Simulator Controls

[bferguson3]

The keys WASDQE, Arrow keys, mouse movement and mouse click are presently bound hard-coded in GL input to what APPEARS to be a headset offset value, but I can't tell for sure.

Input should never be hard-coded. These also don't generate keyboard callbacks, so they can't be overridden by lovr.keyboard.

Suggested:
Merge lovr.keyboard as a base library and implement these controls as lovr-layer callbacks instead

Repro steps:

1. Utilize a specular light source to illuminate a model (passing camera/view position to the shader)
2. Set mirror to:
   lovr.mirror()
   lovr.graphics.clear()
   lovr.draw()
   end
3. Start app and use wasdqe/arrows and observe light source moves despite there being "no input code"

Further testing:
Tying wasd or arrows to a transform offset creates all sorts of lighting glitches when changing position and rotation of the viewpoint.

[bjornbytes]

What would the "lovr-layer callbacks" be? I also want the fake headset controls to be moved up into Lua where they can be more customizable, but I haven't been able to come up with a good way to do it

[bferguson3]

Imo lovr-keyboard should be integrated into the base code as a built-in library, and the headset controls should simply be remapped to use them, i.e. lovr.keyboard.isDown("w") { headsetOffset.z [...]

This way users can override them if they wish but they are still fully functional and hidden by default.

[bjornbytes]

Progress on this has been made: There are lovr.keypressed and lovr.keyreleased callbacks. Moving the desktop headset driver controls into Lua is still a bit tricky though. Ideas I'm going to explore are:

• Add "Space" objects similar to what openxr/webxr have that let you have arbitrary reference frames. Maybe you can use keyboard/mouse input in Lua to define the origin for a Space and then you have some way of telling the headset module to apply that to its views.
• Something like lovr.headset.updateSimulatedTransform could take inputs and return a simulated head transform. This could be used with lovr.graphics.setViewPose to simulate a camera, or be combined with the Space idea above so that lovr.headset.getPose still works.

Tricky, still kinda fuzzy, but getting closer!