How to map a building in 3D where the color of the facade is different from, for example, the 5th floor?
That is, for example, floors 0-4: blue, floors 5-8: green. Is the only way is to overlay two [building:part] with different colors, [height]s and [min_height]s?
What about a building where each of the four outer walls is in a different color? Will adding an unclosed line (edge) connecting the two corners of the building render? That was my idea, but I haven’t tested whether it would work.
OSM2World supports ways tagged building:wall=yes with attributes such as building:colour=*, but that’s non-standard and undocumented, so I believe no one else does. For this to work, the wall ways need to share the nodes of the building outline (the corners + any nodes in between, such as entrances).