衝突判定
For simplicity, we will give an example using bounding spheres, although it has been noted that spheres are undesirable in many cases.
If E {\displaystyle E} is a set of triangles, we can precalculate a bounding sphere B ( E ) {\displaystyle B(E)} . There are many ways of choosing B ( E ) {\displaystyle B(E)} , we only assume that B ( E ) {\displaystyle B(E)} is a sphere that completely contains E {\displaystyle E} and is as small as possible.
Ahead of time, we can compute B ( S ) {\displaystyle B(S)} and B ( T ) {\displaystyle B(T)} . Clearly, if these two spheres do not intersect (and that is very easy to test), then neither do S {\displaystyle S} and T {\displaystyle T} .