Hi guys, super new to blender, currently following Sabastian Lague’s tutorial on youtube and can’t seem to get the copy rotation bone constraint to work.
I want to copy the rotation of the leg IK bone to the foot bone so that when I rotate the IK bone, the foot and toes bones rotate with it. So as per the tutorial, I add a copy rotation constraint to the foot bone, turn off inherit rotation, set the target to LegIK.L and set the space to local with parent and it doesn’t work as intended.
The problem is, the lower and upper leg bones seem to want to rotate with the newly constrained foot bone, whereas, I’d like the foot to rotate separate from the leg bones, based on my manipulation of the IK bone. I can manage to create my poses and whatnot regardless of this issue, but it is a bit more difficult and I would really appreciate some help!
Also, since I am a new user, the website will not allow me to upload my blend file to my post, I realize that makes things much more difficult to troubleshoot and I apologize.
Thanks in advance,
ManInBlack
This suggests an issue with the IK constraint and not the copy rotation constraint. If you rotate the foot bone directly without using any copy rotation constraints, do the leg bones still do this? Which bone in the chain is the owner (not the target) of the IK constraint, and does this IK constraint have rotation enabled (by default it shouldn’t)?
In general, you’ll want to pay very close attention to which bones inherit any kind of transform from any other bone. Even if you disable “inherit rotation” it can still lead to issues.
If this doesn’t help, my next advice is to keep posting here until you are allowed to post .blends. Then it will be much easier to help!
Thanks for the reply Rocketman, to answer your questions in order:
I removed the copy rotation constraint from the foot bone and tried rotating it directly and the lower leg bone did not move with it this time. But I would like the foot to follow the rotation of the IK bone.
The bone that the IK restraint is applied to is the lower leg bone I’ve double checked and “enable rotation” is definitely turned off.
I suppose I should note that the tutorial I’m following was made in 2017 and uses an older version of blender, I’m currently using 2.8. Lol… I must say this is somewhat frustrating, I’ve spent a lot of time trying to figure this out and it should be relatively simple but it’s probably something my newbie self is missing.
I agree with you, I’ll make a few more posts to enable me to upload my blend file and then hopefully that way we can get to the bottom of this issue.
I’ve looked at your file. I don’t see what the problem is. Foot.L is appropriately copying the rotation of LegIK.L. The rotation of LegIK.L is not affecting the rotation of LowerLeg.L or UpperLeg.L. (Of course, the position of LegIK.L is affecting those rotations, as it is an IK bone.) The IK-driven rotation of the foot’s parent is not affecting the rotation of the foot.
Note that this isn’t quite how I’d do it myself, but I’m not sure that my way is any better, it’s just what I’m familiar with-- I’d probably copy world space rotation from a duplicate of the bone that was reparented to the IK target, or else I’d parent the foot to the IK target and give it a copy position constraint targeting the tail of lowerleg. Just saying, because I’m not exactly sure how all this local-with-parent stuff is going to behave, only that it seems like it’s working in your file.
True, while this isn’t imperative to me being able to complete the pose I suppose I was just wondering why it doesn’t function like it did in the video with the copy rotation restraint applied.
Here is a link to the video that I’m trying to base this manner of rotation off of. You’ll find the clip at 16:06.
You’ll notice that after he has applied the copy rotation constraint to the foot bone, as he rotates the IK, both bones rotate separate from the lower leg bone.
Perhaps this is just due to him using an older version of blender?
In any case, it’s good to hear that it’s functioning properly and I appreciate the insight.
I’m not sure what you mean “separate from the lower leg bone.” In your file, your lower leg bone’s rotation has no affect on the rotation of the foot. That’s as separate as you can get without tearing the foot off the shin (and he doesn’t do that in the video either.)
In the X axis, it is rotating the same way. In the Z and Y axes, you can click the “invert” box on the constraint to make it follow in the opposite direction from what it’s doing. In the video, he mentions that you may need to do this. It’s going to depend on the specific axes (roll) you’ve set up for the bones involved-- presumably, not just the IK target and foot, but the parent of each, although again, I’m not super familiar with doing it this way.
Of course, in that file, you’re also in global mode, rotating about a pivot point rather than the bone origin. So that’s going to affect the exact way that things rotate.
Oo I feel dumb lol -_-… it was the origin of the rotation duhh. Sorry, I’m new.
Well thank you again for your patience and your assistance … currently face palming.
