This allows to import complex meshes as convex meshes, which are made up of multiple convex pieces. In contrast to the convex decomposition, it doesn't try to get close to the original shape, instead it just builds one convex hull for each material group.

So for example this triangle mesh which has two different materials:

Ends up like this:

That can then be used for dynamic rigid bodies.

Of course this is even more interesting, when each material group is already built as a good collider mesh, then the result can actually represent the real shape quite well.

Each material can get it's own surface, as well.