I was reading up on the stunning work Crytek are doing in Germany – they mention ccd-ik as one approach to parametric animation. CCDIK or ‘Cyclic-Coordynate Descent Inverse kinematics’ is a simple non-analytical approach to IK that doesnt envolve trigonometry, locking bone chains to two or even a deterministic ik goal – the goal with this system can be anywhere, and so can the number of bones in the chain and where the ik starts and ends from.
I’ll look into this more – i have a funny idea that CAT tools use the same approach to FIK.
Edit: I dont know how the swivel/pole vector is handled, but I have some ideas.