Since Quake 1 (I think it was the first), level design tools for FPS games have used solid brushes and CSG operations to define level geometry instead of more conventional poly modeling tools you see in general purpose 3d applications like 3DS MAX.
Why is this? Is it:
- More productive for the level designer?
- More likely to lead to closed geometry that won't screw up potentially visible set pre-calc?
- Results in lower poly count (more cumbersome tools dissuade designers from adding too much detail)?