Game Engine Architecture, 2nd Edition

12Collision and Rigid Body Dynamics

In the real world, solid objects are inherently, well. . . solid. They generally avoid doing impossible things, like passing through one another, all by themselves. But in a virtual game world, objects don’t do anything unless we tell them to, and game programmers must make an explicit effort to ensure that objects do not pass through one another. This is the role of one of the central components of any game engine—the collision detection system.

A game engine’s collision system is often closely integrated with a physics engine. Of course, the field of physics is vast, and what most of today’s game engines call “physics” is more accurately described as a rigid body dynamics simulation. A rigid body is an idealized, ...