Game Development Reference
The purpose of this whirlwind tour of other approaches is to give you a basic vocabu-
lary and understanding. When looking through the bewildering array of physics and
simulation resources available on the Internet, you should now be able to understand
how they fit into the whole picture and how our engine relates to them.
There are a couple of open source physics systems on the Net that you can com-
pare with the one we've built. ODE (the Open Dynamics Engine) in particular is
widely used in hobby projects. It is a solid implementation, but finding your way
around how the code works can be difficult. Like our engine, it is not primarily built
For a more comprehensive mathematical survey of different physics techniques
that are useful in games, I'd recommend Eberly . David assumes more mathe-
matical knowledge than I have here, but if you've followed this topic through, you're
probably ready to get started. The Eberly book doesn't cover how to build a complete
general-purpose engine but looks at a massive range of techniques and tricks that can
be used on their own or incorporated into our engine.
David Baraff has done more than anyone in disseminating information on
Jacobian-based approaches to physics. His work is on the desk of many physics devel-
opers I know. A good introduction to his work is Baraff and Witkin .