[Maya] Dynamic chain rig with ikSpline issue

maya
rigging

#1

Hi there!
I have an issue with my prop rig. I have made a simple python script which creates joint to a specified position, in this case the top of a chain link, then it creates a skin cluster between an individual link and joint, then it creates cv curve along the joint chain, then the script makes the curve dynamic and creates an ik spline handle between the first joint and the last joint, and the handle uses the created cv curve. I’ve set the follicle point lock - no attach. Due to the fact that both end of my chain are attached, I’ve made a transform constraint to the end of my dynamic curve.

My issue with the setup is that during the simulation the ik handle does not stay in one place but rather shifts around despite me trying to constrain it to one place.

I thought the changing length of my curve cause the problem, I’ve normalized the arc length with a curve info node and divided it with its starting length, then I connected it to IK handle scale, but it not solved the case.

Please help.
Thanks,
G.


#2

If you’re using an IK spline then the IK handle itself doesn’t do anything transform-wise. But if you have been working with the curve already, then the length dipping below its initial value can definitely cause weird flips in the spline joints. Adjusting the length after the simulation may actually make this worse - an IK spline length constrains itself anyways due to the joint translate not being affected by IK.

Can I ask why you aren’t just using point-lock to both ends? Using that and forgetting about the curve length may get you what you want.