Original Post
What I need is to select areas on the surface of a 3D object for some processing. This, I can do, no problem. Here''s where I''m having problems. When I select another area, the way I want the selection to work is that any part of the previous selection should be "cut off" and replaced by the new selection unless the new selection is completely inside the old one.
The surfaces are represented by triangles, in no particular order (I''m sorry to say) and the "cut off" point are mostly on triangle segments.
So my question is: how can I, when creating a new triangle, remove any parts of a triangle that is under it and divide the resulting shape into triangles again (and if it can be in an optimal without sliver triangles it would be perfect).