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

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.