Yes, there very much should be a 3rd dimension. If you're having issues I'd appreciate if you could file an issue on https://github.com/felixpalmer/procedural-gl-js mentioning what device you have along with the output from https://webglreport.com/

In the meantime, there are some video captures on my twitter: https://twitter.com/pheeelicks

Same here. Maybe it does not work correctly on all platforms? I'm using an old Android phone (Samsung G8)

Same here. Could it be some rate limiting of the height data? I'm on a Samsung S20.

Same. I'm on desktop Firefox 84