Hi!
There is no "API" so far, but all the code is included and made as independant "bricks" that you could reuse.
For example, doors and windows are generated using "ProceduralOpening.cs" you can drop the prefab with the same name in a blank scene, and call Generate() with the parameters you want. it's the same for generating a building, or a room, you have a Generate() method where you have to pass the set of points and openings. That will generate the floor, walls and ceiling for you.
You also have serialization and deserialization methods, so you can save and load a generated object, and make your own editor or your own interior designer.
The ceiling is generated but I did not added a material customizer to it, that's something I will add on the todo list.
Finally, I'm providing a camera system but you are free to use any camera you like in your own editor or in the "Play mode" scene. The play mode scene shows how to just load and instantiate the final result, there's no walking camera there, so if you drop a VR camera prefab, that will work just fine!
Let me know if you have any other questions.
regards,
Anthony