None of the options stop rendering or hide it or whatever on the hmd.
Code:
viz.MainWindow.visible(False)
Works at hiding the mirrored window on my PC's monitor but the scene is still being rendered on the HMD. Interestingly
Doesn't seem to do anything.
I will have difficulty in hiding the scene with a quad since the user is immersed in the scene (subject can walk around and interact with the scene). In order to hide the scene with a quad I'd have to have reliable information about the head position and orientation which in the scenarios where I want to hide things, this data is inaccurate.
Alternatively I think I'll try positioning a black sphere around the head when I want to hide the scene, so that only the position data needs to be robust.