[Algorithms] Animation splines

[Joe A. <jo...@ut...>]

Hi,

I want to convert some euler based rotation hermite splines into quaternion
based hermite splines.

My unenlightened approach would be:
1) Split all euler based rotation so the x, y, z rotation curves have
keyframes at the exact same positions.
2) Iterate through all keys. Take the tangents and key value from each
rotation curve and convert it into a quaternion tangent and key value.

I cant figure out how to solve the first problem. Basically how do I insert
a keyframe which will not change the appearance of the curve?

Is it enough to calculate the tangent at the position I want to insert the
keyframe and use that as the tangent?
How do I calculate the tangent at an arbitrary position in the curve?


I am also not sure if the method would work correctly at all. I mean
interpolation between euler angles and quaternions will most likely be
different because well the interpolation method is just different. Is this a
problem visible in a game? What are your experiences?
Or are you forcing artists to use quaternion splines for animation?

Joachim Ante 
www.otee.dk