Tutorial 4

CSG Best Practices

While Constructive Solid Geometry may be easy to understand and use, there are several important considerations to take into account while designing a level. They are common mistakes that can potentially lead to a very high polygon count and extremely slow rebuilds.

Additive Brushes Cut Holes

When two additive brushes intersect each other, the interior polygons are removed. For example, imagine a floor with several boxes placed on it. Every box touching the floor will have its bottom polygons removed and cause a square to be cut out of the floor. This results in a lot of additional floor polygons, also called "heavy splitting", to represent the holes in the floor.

NoCSG

This brush mode disables all CSG behavior. Some editors call them "semi-solids", "detail brushes" or "func_detail". If the boxes on the floor are set to be NoCSG, the floor will no longer be affected by them and no holes are created. However, the bottom polygons of the boxes do not get removed either. You should exclude these faces manually to get the most optimal result.