I used Unity's layers system (more on that in sibling comment: https://news.ycombinator.com/item?id=24367460).
I have zero experience with WebVR, but solution you linked seems sensible.
I have zero experience with WebVR, but solution you linked seems sensible.
But maybe I'll get back to work on my hack. Some suggestions are here: https://stackoverflow.com/questions/53775620/webvr-update-sc...