Game Physics Engine Development, 2nd Edition

80 Chapter 5 Adding General Forces

For forces that apply over an extended period of time, it would be better to hav e

some automated mechanism. We can make it easier to manage these long-term forces

by creating a registry . A force registers itself with a particle, and then will be asked to

provide a force each frame. I called these “force generators.”

5.2 Force Generators

We have a mechanism for applying multiple forces to an object. We now need to work

out where these forces come from. The force of gravity is fairly intuitive: it is always

present for all objects in the game.

Some forces arise because of the behavior of an object, such as a dedicated drag

force. Other forces are a consequence of the environment that an object finds itself

in; a buoyan ...