Hello everybody, I'm writing a skeletal animation engine that supports TCB keyframe interpolation, so that it can simulate motions exported from 3DS MAX. My quaternion's code is based on an example from Magic Software: http://www.magic-software.com/Applications/KeyframeAnimation/KeyframeAnimation.html This example assumes that consecutive quaternions form an acute angle. Since 3DS MAX don't have this limitation, I want to overcome this in my engine. How do I modify the algorithm? Or any links to a better algorithm? I'm not good at Maths and I have no idea on that...... Thanks Man [edited by - mannam on February 11, 2003 10:46:58 PM]