OpenCSG is a library that does image-based Constructive Solid Geometry
rendering using OpenGL.

To run OpenCSG well, you should have graphics hardware with
a good fill rate. NVidia GeForce and ATI Radeon qualify. The
OpenCSG::OcclusionQuery option requires occlusion queries, which are
available since Radeon 9x00 (x>=5) and GeForce3 (but not GeForce4MX).