Rigidbody in 3D
Quaternion Time
I hate to start off the article like this. I really do. But it really wouldn't be a discussion of 3D simulation if we didn't jump right into quaternions. Before I start, however, I recommend you take a look at this article. Quaternions have been written about over and over throughout the years (and I have read many articles about them over and over throughout the years), so I will not waste your time describing every single detail here. The article that I linked to should provide you enough information to begin to understand what quaternions are and why they're important. That being said, I will provide a brief intro to quaternions here, as well as my own C++ implementation of their algebra. (This article is also quite useful: Dance's With Code Website)
Live Example