How to get rotation data from the IK bone?

[nikars]

Hey everyone, im building a rig and i have some shape keys driven from bone rotation, and all works great until i turn IK on and for some reason the bone rotation data is no longer shown in Euler

I reaaaally need this data. I have already tried crutching by adding additional bone with copy rotation constraint but it also shows nothing.

Help pls

[bandages]

The transform channels are pre-constraint values. Your bone does, in fact, have no rotation before the evaluation of the constraint.

There are multiple kinds of angles that you can use for drivers. If you get the transform channel instead of a single property, you can get the post-constraint transform.

[nikars]

Thank you so much!!!

One last small question, i have tried limiting rotation of the IK solved bone in bone properties pannel and also with constraints but nothing seem to work. Is this a known limitation or am i doing something wrong?

[bandages]

In general, constraints won’t affect an IK bone. (You can parent a bone to an IK bone and constrain the child though…) Angle limits as set in properties/bone/IK work fine, although I’d be careful of them-- it’s easy to create IK twitch by going crazy on the angle limits. If the angle limits aren’t working for you, I’d have to see a file to see what’s going on.

[nikars]

Here’s a issue replicated in clean scene with bones only. As you can see the selected bone goes out from the constrained area.
I managed to dig up some bug report from decade ago where somebody brought up simmilar issue and basically devs said it was a known issue

[bandages]

Don’t know what to tell you. It works for me:

[nikars]

Try adding pole target

[bandages]

I think the pole target overrides the initial bone’s angle limits. But other bones still work fine, and you probably don’t need a pole target anyways. (Try giving a non-deforming parent to the first bone in the chain, and then rotate that parent.)