Should your world map have it's own collision object?

Question

I am attempting to understand collision detection at the moment. I have seen many examples of a simple flat plane with boxes or cubes which move around on the plane and react when the touch each other (or stop at the plane when dropped).

What I am not finding though are more advanced examples where instead of just a flat plane, your map is made up of hills, buildings, walls, etc.

Since all of the examples I have found this far use simple primitive collision object types (boxes and spheres), I am curious what the best approach would be for creating a collision object for something like a game map (like dust2 in counter-strike).

After reading through the bullet documentation I found that you can create a collision object from a triangle mesh, which leads me to believe this might be the best approach. However if your map consists of complex geometry (say hundreds of thousands of verticies and faces), would this be too detailed to use as a collision mesh? Would it then be better to create a separate collision version of the map which is made of simple low poly shapes?

My gut is saying "go with the separate low poly version", but if there is no reason for the extra work, it would make more sense to just use the high poly mesh.

Answer 1

Generating collision from the mesh itself is the usual approach for terrain. This is especially not a performance issue on counter strike-sized maps, as long as you keep the vert density at a somewhat sane value (0.5-10m).

If your level is already very geometric, or you need to have perfectly flat collision surfaces for some reason, look into replacing the collision with a bunch of collision boxes.