Parent the camera to a small Blitz sphere and use Blitz collision checking against the visible room mesh entity (not the TriMesh). When the sphere comes into contact with the room mesh, both it and the camera will not be able to penetrate it.
You will probably find much more info about this in the Blitz3D programming forums, as it applies whether physics are used or not.
You will probably find much more info about this in the Blitz3D programming forums, as it applies whether physics are used or not.