Constructive solid geometry?

Hi,
I read about CSG


and I have the feeling that it might be very useful for some kinds of games. So I was wondering if you could tell me what csg could be used for. Is it possible to render csg objects directly without converting them to a polygon mesh first?

you would either convert them to triangle meshes (marching cubes)
or use raycasting with depth functions http://www.iquilezles.org/www/articles/distfunctions/distfunctions.htm