Game Physics Engine Development, 2nd Edition

15

Resting Contacts

and Friction

o far I’ve used the terms contacts and collisions interchangeably . The collision

Sdetector finds pairs of objects that are touching (i.e., in contact) or interpen-

etrating. The collision resolution algorithm manipulates these objects in physically

believable ways.

From this point on, I will make a distinction between the two terms: a con tact is

any location in which objects are touching or interpenetrating, whereas a collision is a

type of contact in which the objects are moving together at speed (this is also called an

impact in some physics systems). This chapter will introduce another type, the resting

contact.