Recently I posted a blog about my first foray into 3D game development using LWJGL. Since then, I've worked on adding simple physics to the game using JBullet (a Java port of the Bullet physics library for C++). However, I've been having difficulty with the angular measurement system it uses. It seems to use quaternion rotation, with which I am quite unfamiliar. Actually, that's a bit of an understatement -- I hadn't even heard of quaternion rotation until a few hours ago. This is especially problematic when it comes to rendering the object, as to render stuff in LWJGL I need to pass vectors in pitch/yaw/roll format. The Javadoc doesn't include any information on the subject, and while there seems to be no shortage of forum threads with similar questions, none of the code they use has actually worked for me. Does anyone know how to convert from JBullet's quaternion-based rotation system to the pitch/yaw/roll one usable in LWJGL?