Greetings, Me and some other guys have created a small BSP engine in JAVA. However there are some major problems when it comes to render maps that are created with an editor such as Worldcraft. Personally I believe that this comes because there isn''t any CSG performed on the polygons. I really have no idea how to implement it, there is tons of information over how to perform/create a BSP, but the information of how to implement CSG seems to be really limited. Also how can you check what''s in the inside of your map and what on the outside, so in short how to perform Hidden surface removal? Can anyone point me to a link that has some good info about these? Cheers P.