The html contains a canonical link which HN uses.

    link rel="canonical" href="//demo.f4map.com"

Ah looking at your link it actually does use roof data! Nice work!

I'd zoomed in on a place where I'd provided building heights and was pleased to see that it did use that. Not all "3D" OSM renderers do even that.

These renderers dearly need better topography though. The resolution is insufficient unfortunately.

The compass button slightly confuses me. I thought the arrow in anticlockwise direction was intended to turn the map anticlockwise, but it actually works like a GPS navigator, i.e., it works as if I turn my car to the left and the direction ahead is always the upward direction on the map.