I've dabbed in collision detection in the past, and here are a couple of notes: * The square root operation is relatively expensive. Don't use it. If you're do

I've dabbed in collision detection in the past, and here are a couple of notes: * The square root operation is relatively expensive. Don't use it. If you're doing point-circle or circle-circle collision detection, you're better off comparing r²< a²+b² than r < sqrt(a²+b²). The same goes for 3D, obviously. * Use a hierarchy of bounding volumes, with coarser bounding volumes calculated at runtime and determined based on the computational cost of the collision detection method. Say you have an element comprised of several sub-elements. You start with a coarse sphere that groups all elements and start by evaluating a collision based on that sphere. If you detect a collision, you re-test with finer-grained bounding volumes. * In some applications it pays off to discretize coordinates and sizes and replace accurate floating point math with less accurate integer math. This approach can be a part of the hierarchical collision detection approach.