Fabrik pops across poles and rolls over

I’m trying to setup a very simple worm like skeleton that uses the fabrik solver. I’m testing with only two bones or I guess three joints. When the front is pulled the following two joints get pulled as needed allowing the worm to slightly coil up. Looking top down on the worm with its head pointing towards the top and tail towards the bottom. When I move the ik handle the head will bend naturally around from 12 to 6 o’clock clockwise. As it crosses 6 or 12 into the opposite Hemisphere the fabrik solver flips the middle joint. So if the bend in the worm is a < shape as it crosses the vertical axis it pops into a > shape. I would like to fix this and instead have it maintain the current bend around the vertical axis.

To add to this I’ve noticed one more oddity, when I pull the ik handle towards the 6 o’clock the worm will roll over length wise completely flipping over.

I would also like to know about this. Is there a way to set a joint target location / pole vector like you can with a 2 joint IK chain? What controls the flipping/popping of the FABRIK ik chain? I can’t seem to figure it out.

I know I’m necroing this, but it’s the first result on google.

1 Like