Returns a Texture that contains whatever is currently rendered to the headset.
Sometimes this can be
nil if the current headset driver doesn't have a mirror texture, which can happen if the driver renders directly to the display. Currently the
vrapi drivers do not have a mirror texture.
It also isn't guaranteed that the same Texture will be returned by subsequent calls to this function. Currently, the
oculus driver exhibits this behavior.
mirror = lovr.headset.getMirrorTexture()
|mirror||Texture||The mirror texture.|