[Maya 2017] Help making ik scapula rig

noface789

Hi all, as the title says I'm trying to make what I imagine to be a simple scapula rig with ik splines, if I could attach the file here, I would. But basically I have a rotate-plane solver from 1 to 3 and single-chain solvers from 2 to 3 and 3 to 4. As you can maybe guess 1 would be the wrist, 2 the elbow, 3 the shoulder, and 4 the scapula.

I'm trying to make it so that when the wrist moves up and down, it pulls the scapula along like a real one would, and when you pull the wrist past the shoulder upward, the shoulder joint should be restricted in how much it can bend, and the scapula should be the only one allowed to pivot the arm upwards, like raising your arms above your head.

I managed to get the wrist to move the scapula when you translate it up and down but it's activating too early. I tried playing around with the IK weights and priorities in the attribute editor so maybe the rotation-plane as the highest priority spline would be able to move without prematurely affecting the scapula, but after tweaking the priority settings for a while I can't seem to get any discernible difference.

Am I implementing this rig the right way? I'm not married to this method and would like to hear suggestions. Simpler obviously better.

Mark Dygert

People usually refer to that shoulder joint as the clavicle, since it is the main shoulder bone that acts like a pivot and is responsible for keeping the scapula in place.
I don't have time to read over your method but there are loads of tutorials on "auto clavicle".

https://www.youtube.com/watch?v=gulC7YrYQeU

https://www.youtube.com/watch?v=ClzZjqcwnCU

noface789

Oh wow that's exactly what I wanted to do. I guess I was using the wrong terminology while researching myself. Thanks

pasha_sevez

The main problem with IK hand and clavicle/scapula is that if you make any dependency from any joint within IK to clavicle you get a DG cycle. Because as you adjust the clavicle, you immediately change the initial point of IK-hand, which leads to recalculating the IK joints and once again adjusts the clavicle and so on. The solution is possible, but not using any direct node connections. I've managed to achieve it using Maya API callbacks.

pasha_sevez

Also including the clavicle into the IK chain is a somewhat questionable thing because the clavicle has a very specific movement rhythm and ratio to be simply calculated using regular IK solver. But in this case you may try to fine tune the stiffness and other parameters of clavicle joint. Probably the result may be acceptable for your needs.