See Also

I think it’s typical to put the Bibliography at the end. However for this series of posts, I’m putting it right at the start. The reason for this is because the Dubious Engine is in no way an original piece of work. I did not invent any of the Physics that powers it. I’d like to think that I’ve organized it in a way that makes it easy to understand and write about, but I certainly didn’t come up with any new algorithms. Everything here has been described somewhere else. Unfortunately I started this so long ago that I’ve lost track of all the things I’ve read, but here are the ones that I can remember:

• allenchou.net – This is the big one, I must have read and re-read every post here dozens of times. If he had source code to post I probably wouldn’t have bothered writing anything.
• 3D Game Engine Programming – The site that finally got me to understand Quaternions. That alone makes it priceless, all the other great articles are just a bonus.
• box2d.org – The simplest code to understand, primarily because it’s in 2D. It’s almost a requirement that you get it running and familiarize yourself with it while creating your own Physics Engine. While it is not 3D, the concepts are familiar enough. Also contains some papers that you have to be much smarter then I am to understand.
• bulletphysics.org – An actual, working Physics Engine, complete with source code. It does everything. Unfortunately it’s very difficult to read through and the documentation is sparse. Still, if you have the time to really truly go digging, the answer is in there.
• Molly Rocket – In 52 minutes you can understand what the GJK algorithm is. Other articles can help you refine it, but really there is no quicker path to understanding.
• Code Cave – Second only to Allen Chou for understanding GJK and EPA. Bonus points for representing 3D concepts using sticks and putty. I may very well rip that off.
• dyn4j.org – More great information about GJK and EPA
• Matrix and Quaternion FAQ – One of those ancient pages out of Internet history (hello purple.com). I can’t find the original version I used to use, but this seems like it’s pretty much the same thing. This is where I was introduced to Quaternions, and my first implementations came from this page. It was so freaking painful.