Using mesh as collision

Hello everyone. Im having problems in creating collisions some of my meshes. Im aware of the usual methods for creating collisions, but none of them seem to work good enough for me. For example, i have a head shaped building, and its a platformer game, so I want the player to be able to walk arround, be inside, and on top of it. So creating collisions based on cubes doesnt seem like the best way to go, it would be like trying to model a simplified head with cubes. It would be very useful if i could import a complex concave mesh as a collision mesh. So i was wondering about the option “use complex as simple”, but when is a mesh too complex for this to be a good idea? my head-building has 9.7k tris.
Also, what about creating a simplified head shape in the 3d program, lets say with a couple thousand polygons (still less than the initial head shape), and select “use complex as simple” for that relatively simple mesh, and no collisions for the complex mesh, then in the level, place the simplified mesh with collisions, hidden and in the same place as the more complex mesh without collisions. It would be like using a custom mesh as a collision mesh.

You can certainly do that, I mean use a second mesh, simplified and disable collisions on your render mesh. I actually use this method in one or two places in my project. I would just say, make that mesh really as simple as you can get away with. Collision is not something you want to just throw in there. Really consider what you’re doing, how much polys etc. You’re talking a couple thousand polys for this mesh, I would suggest thinking in terms of hundreds, or less, not thousands. It ultimately does depend but, yeah, think in real low poly terms here and don’t over use this for convenience, make the effort to do good low impact collisions.

Just use lods for collision. Also physX is really fast. Even on mobile game you can have hundred of thousands polys for physics without significant performance problems.

Thanks for the advice, using lods for collissions sounds like a good idea