Re: [Algorithms] Representing Animation Key Frame with Quaternion + Translation Vector

[Jon W. <jw...@gm...>]

Lim Sin Chian wrote:
>
> Just wondering if anyone has done this before and whether it is really 
> better in terms of performance and accuracy.

I'm under the impression that everybody does that. Not only does it save 
space (assuming you don't need scale), but it also interpolates much 
better. Interpolating between two frames with a matrix looks pretty 
crufty. The only thing to watch out for is to make sure you go the 
"short way" around -- dot product the two quaternions, and if the 
outcome is negative, negate all the values of the destination.

To compose quaternions, you just multiply them. Because it's a 
rotation-translation pair, if it's parent relative, then you apply the 
parent rotation to the child translation, and then apply your own 
rotation around that point.

Sincerely,

jw