I’m working on a Polyfjord tut project for fun and ran into an IK problem I remember form years ago… On a long IK chain, when positioning, if the Y-axis
of the IK_target passes zero (plus or minus) relative to the root bone axis, the whole thing snaps into a new position with a new IK solve. I mostly understand WHY it’s happening, and years ago (like version 2.48 i think) I had mostly fixed it on what I was working on. But that was a long time ago and I don’t remember everything I did or how. I’m pretty sure it was something with rotation/location constraints, but I’m at a loss… especially since I only recently was able to move from 2.79 to 3.x (wow there’s a lot to relearn!)
As always, any help is greatly appreciated, even if it’s just pointing me in the right direction of reading material.
Your chain is totally straight, so you haven’t given it any preferred direction of bend. Switch to individual origins pivot, select all bones in a chain in pose, and give it a rotation in X or Z. (Turning off IK temporarily to see what you’re doing is wise.) Doing this will indicate to Blender that you want to limit the angles available to each bone to the rotation you’ve indicated, at which point you’ll stop having a million different solutions to your IK chain, and the twitch will go away.
I’d also recommend disabling the angle limits on your final bone, this can only cause problems and not help you.
Thank you. I think I remember doing something similar way back when… I think I had originally went bone-by-bone setting the limits, but it was a much simpler rig. I wasn’t aware you could select them all and do it at the same time.
