First off, Final IK is amazing, well worth the money! Good job on such a quality product.
I'm trying to gain more control over the upper body, namely the arms, in FBBIK. Ideally what I want is an elbow effector for position that would also rotate the shoulder to match the effectors rotation. Then I would independently pitch the forearm at the elbow and rotate the hand how I see fit without positional effectors.
I managed to wire in some trigonometry to achieve this, treating the shoulder-elbow-hand as my triangle to solve where I wanted the elbow goal and hand effector, but it all seems a bit much. I tried combinations of CCD chains and FABRIK with root but couldn't affect the rotation of the elbow, and wasn't sure if it was working right.
Now that I think of it, a FABRIK root chain from spine, to clavicle, shoulders, elbows then hands would be nice where I could use rotation limits unlike with FBBIK. But how would I alter rotations of joints so that chains down the line are affected?
Any advice is much appreciated. Thanks!