RUIS for Processing is officially in legacy status. The last version (0.90) only works on Processing 1.5.1, while the latest Processing version is 3.0. Processing is a great platform for beginners, but it doesn't have all the 3D math and scene composition features that ease VR development.

If you have any questions related to RUIS for Processing, bear with me as I try to remember its details, since it's been awhile since I touched the codebase :-)