A sphere like a planet

I studied VLY a little bit in the past days (water and sky are missing to me too), I modified it a little bit to use it with the kinect How to fly using kinect - #4 by sonostrano - question - Forum and in that patch, if I understand well, the terrain is a realtime-generated plane.
I’d like to use a sphere or the mesh of a planet (with mountains, hills etc).