CompuServe Messages

Grant- >> >> Sometimes the axis is <1,0,0> and sometimes it is <-1,0,0>, but the sign of the angle is not inverting. This is causing our animated model suddenly change heading by 90 degrees. Is this in some way related to quaternions? << << Whoops! I meant 180 degrees. >> Is this happening on a key to key basis through a single motion path, or on key zero? << It's happening on frames after zero on a key to key basis through a single motion path. >> I think you need to be interpolating the quaternians and then converting that result into a Euler. Adding together Euler's won't give you the results you want because of discontinuities in the tan function. << Actually, we are not currently doing any interpolation. We have 3D Studio spit out keyframe information for every frame, and use that. You may also want to take a look at Quatern.zip in the library. It's a compilation of all the quaterian related threads over the last 2 years. It's good stuff. << Yes, I suspect it is a quaternion quirk. I'll investigate your suggestion. Thanks for all the great help! Mark Hodges Gravity Inc.