Yeah, there are some simple but effective optimisations for pure subtraction, particularly the classification of the polygons during the splitting.

Technically, if you know the object being subtracted is made up of one connected mesh (floating geometry has been dealt with) then you can get rid of the ray classification part of things, since you know, that if a rocket hit an object, then it must have hit geometry, so if no intersections occur during the CSG, then you know the mesh is ''inside'' the explosion mesh, so completely delete the object.

Thats just one of a number of small things I''ve spotted.

Yeah, my world is made up of two main types of objects - deformable and non-deformable. It isn''t made out of one large world mesh, but separate objects e.g. a house or pillar.

I know you mean optimise the data for CSG deletion, however, I believe that the data must have the same sort of flexibility and structure as any other CSG type - union etc. Because not only do you have to delete geometry, but you must also insert new geometry when splitting triangles - and this is the same in all CSG cases. It''s only the classification of triangles that determines what you keep and delete.

I haven''t found any really good data optimisations for deletion so far anyway