Over the past 3 months I have been working on OSM2World for Google Summer of Code. The aim of my project was to add support for indoor tagging, meaning rendering indoor data in 3D. This includes basic features such as rooms and corridors, windows and doors as well as objects that may span levels such as stairs and barriers.
The code that I have produced can be seen in these 3 pull requests:
https://github.com/tordanik/OSM2World/pull/166
https://github.com/tordanik/OSM2World/pull/168
https://github.com/tordanik/OSM2World/pull/169
And the results of my work are as follows.