Hi,
I’m not a developer but with this example it was not too hard to understand 
To build the floorplan I used: http://www.sweethome3d.com/
Simple and free, created this in about a day, but that’s because I also build some custom furniture that I couldn’t find 
building the plan itself is done in about an hour, very nice tool
Simple tutorial: https://www.youtube.com/playlist?list=PLqazFFzUAPc6vIE_JM3Ysis39MrANKxx_
Import 3D models and textures: http://www.sweethome3d.com/freeModels.jsp https://3dwarehouse.sketchup.com/ https://archive3d.net/ https://free3dbase.com/free-3d-models/3d-models/1
good luck!
