IK Pole problem after moving was cancelled

Support Animation and Rigging
1

Hi, forum mates.
I have an annoying problem with the IK pole.

So, there is IK assigned to “lower arm” bone and “pole bone” as pole target for it.
The angle of the pole is correct here, and everything looks good when I move the pole.
But if I cancel the move with the right mouse button, it breaks, and the “lower arm” bone does not turn back. I tried to explain it in a small drawing.

pole_problem_p1
pole_problem_p11612×886 145 KB

The blue line is what it looks like when I’m not moving anything.
The red line is what it looked like when I started moving the pole, but if I cancel moving the pole (with mouse right-clicking), it will turn back, but the “lower arm” bone will not.

It’s weird because if I press Ctrl+Z to undo or move any other bone, it turns back and everything looks right.
Do you have any thoughts on how to fix this?

2

Hi, the ik pole should be placed behind the elbow not in front of it.
Can you post your file please that will make it easier to understand.

3

Yes, I did. The pole is placed behind the elbow. And as I said, it works well until the movement is canceled.
Imagine that some bone is moving, and you cancel this movement by right-clicking. Thus, the bone should turn back, but it remains in the same position.
It looks like a bug, very strange.
Sorry, but I can’t post this file because I’m new to this forum.

4

Is the IK controller or the Pole Target parented to anything that might cause a loop?

You can try unparenting the IK controller and the Pole Target and see if that helps.

If you want to share the file, you can load it to a file sharing site and share the link.

5

It looks like you have parented the pole to the bone could that have created the loop?

pole
pole1612×886 163 KB

1 Like
6

The pole is parented to root bone, but what kind of loop is can to be here?
Ok, I share it on Google Drive. Here is my file: https://drive.google.com/file/d/1Xu4mZsjTyB--dJKNgBI2hrqN5kTdAbGL/view?usp=drive_link

7

The loop seems to be be coming from the limit distance constraint on the Elbow Pole. When I deleted it (just disabling it didn’t fix anything) the arm worked as expected. The pole target is controlling a bone that is also controlling it, so there’s a loop.

I don’t know if this helps you at all, but when I switched the constraint so the pole target was distanced from the red cube at the shoulder, instead of the hidden deform bone, it maintained pretty much the same distance, and didn’t have the problem.

pole_problemTest.blend (1.5 MB)

8

I got it! Thank you so mush!

1 Like
9

Loading the file posted in blender 4.0.2 gives me this error message in the console:

Dependency cycle detected:
  OBhands_rig/hand_up-L/POSE_IK_SOLVER() depends on
  OBhands_rig/IK-L/BONE_DONE() via 'IK'
  OBhands_rig/IK-L/BONE_READY() via 'Ready -> Done'
  OBhands_rig/IK-L/BONE_CONSTRAINTS() via 'Constraints -> Ready'
  OBhands_rig/hand_up-L/BONE_DONE() via 'Limit Distance'
  OBhands_rig/hand_up-L/POSE_IK_SOLVER() via 'IK Chain Result'
Detected 1 dependency cycles

I know this has be solved, but I just wanted to say - when bones behave strangely, check the console for error messages.

Randy

1 Like
10

Wow, I didn’t know about that! This should be useful. Thank you, Randy!