From triangle collision to mesh collision :P

[{MSX}]

For example with help of these functions: D3DXComputeBoundingSphere, D3DXComputeBoundingBox.

I don't use DX.
Anyway i think that functions only gives you one sphere or one box, while i think JSoftware uses a hierarchy of boxes which far better

A single bounding box or sphere works very bed with a torus