combine targetless IK chain with copy rotation constraints

Question

I have setup a bone chain with a copy rotation constraint such that the entire chain bends when i rotate the root bone:

At the same time i have setup a targetless IK constraint on the chain tip which spans along the chain towards the root bone.

When the root bone is not rotated, then i can move the chain tip and all bones behave just right (as expected).

However as soon as i rotate the root bone a bit, then moving the chain tip results in odd behavior. This is because the IK move also changes the rotation of the Root bone. And since this rotation affects all other bones in the chain, i get a clash, and the chain begins to jump around when i move the tip.

I have enabled Offset for all rotation constraints, so that i can rotate each bone individually. But this seems to be not enough to solve this problem.

Actually i wonder if this can be solved at all.

Answer 1

What you are trying to do is to have FK control and IK control on the same bone chain.

As you stated there are dependency issues, and this cannot ever work.

What you need to do is to make 2 separate chains - FK and IK, and a 3rd deform chain that blends between them.

Another thing you can do is to have main IK chain for the general shape, and then FK chain that copies the main one and is there only for fine minor tweaks - but this will break the endpoint location.