Issue with ik when character turns
Moderators: Víctor Paredes, Belgarath, slowtiger
-
- Posts: 5
- Joined: Sat Jul 19, 2025 4:38 pm
Issue with ik when character turns
Hey everyone! Working on my first rig.
Any ideas why isn't IK working on this leg? Works perfectly fine on the other leg but if i turn my character the ik moves away from the bones, and does not work properly
Thanks!
https://drive.google.com/file/d/1D9aQrQ ... p=drivesdk
Any ideas why isn't IK working on this leg? Works perfectly fine on the other leg but if i turn my character the ik moves away from the bones, and does not work properly
Thanks!
https://drive.google.com/file/d/1D9aQrQ ... p=drivesdk
- synthsin75
- Posts: 10333
- Joined: Mon Jan 14, 2008 2:20 pm
- Location: Oklahoma
- Contact:
Re: Issue with ik when character turns
Probably a bone inadvertently keyframed in the turn action.
- Wes
Donations: https://www.paypal.com/paypalme/synthsin75 (Thx, everyone.)
https://www.youtube.com/user/synthsin75
Scripting reference: https://mohoscripting.com/
Donations: https://www.paypal.com/paypalme/synthsin75 (Thx, everyone.)
https://www.youtube.com/user/synthsin75
Scripting reference: https://mohoscripting.com/
-
- Posts: 5
- Joined: Sat Jul 19, 2025 4:38 pm
Re: Issue with ik when character turns
I checked the keyframes from the turning action, but there aren’t any strange keyframes in the IK bone or the leg bone.
When I turned the legs, I did it by moving their IKs. I’m not sure if that could be the problem. I just can’t figure out why it only happens to that leg
Can you show me, like, with an example of how can I fix it?
When I turned the legs, I did it by moving their IKs. I’m not sure if that could be the problem. I just can’t figure out why it only happens to that leg
Can you show me, like, with an example of how can I fix it?
Re: Issue with ik when character turns
Hi!
I agree with Synthsin75; it looks like a conflict in one or more Smart Bones.
Can you post the project? You can remove the artwork if you wish, as it's likely that only the bones are needed for troubleshooting. Otherwise, it's just a guessing game.
I agree with Synthsin75; it looks like a conflict in one or more Smart Bones.
Can you post the project? You can remove the artwork if you wish, as it's likely that only the bones are needed for troubleshooting. Otherwise, it's just a guessing game.
NEW! Visit our Little Green Dog Channel on YouTube!
D.R. Greenlaw
Artist/Partner - Little Green Dog
Little Green Dog Channel | Greenlaw's Demo Reel Channel
D.R. Greenlaw
Artist/Partner - Little Green Dog
Little Green Dog Channel | Greenlaw's Demo Reel Channel
-
- Posts: 5
- Joined: Sat Jul 19, 2025 4:38 pm
- synthsin75
- Posts: 10333
- Joined: Mon Jan 14, 2008 2:20 pm
- Location: Oklahoma
- Contact:
Re: Issue with ik when character turns
None of the turn actions have any other bones keyframed, so I can't see the problem shown in your video.
- Wes
Donations: https://www.paypal.com/paypalme/synthsin75 (Thx, everyone.)
https://www.youtube.com/user/synthsin75
Scripting reference: https://mohoscripting.com/
Donations: https://www.paypal.com/paypalme/synthsin75 (Thx, everyone.)
https://www.youtube.com/user/synthsin75
Scripting reference: https://mohoscripting.com/
-
- Posts: 5
- Joined: Sat Jul 19, 2025 4:38 pm
Re: Issue with ik when character turns
I'm trying to animate a walk from the side view of my character. The problem is that when I turn my character to side in the mainline, and then I move the ik anywhere, it doesn't work correctly.
In the video, when I turned the character, I moved the ik upwards to show that the ik was moving away
In the video, when I turned the character, I moved the ik upwards to show that the ik was moving away
Re: Issue with ik when character turns
Hi Farenzzzzno,
I didn't have time to look deeply, but at a glance, it seems you have many bones, including other smart bones, under the control of GIRO CUERPO. In the image below, Moho is highlighting all the bones controlled by GIRO CUERPO.

I mainly suspect that the rotation of the thigh bone is being 'locked' by the GIRO CUERPO Smart Bone because that's how it's keyframed, and this can make the IK appear to be broken. In other words, the IK is fine, but the Smart Bone is overriding the leg rotation.
My guess is that your intention was to keyframe only the X movement of some bones in the Smart Bone, so you might want to check that.
For example, here in the GIRO CUERPO Smart Bone timeline, I see rotation keys for the Thigh and Shin bones, and the Thigh bone is keyframed to stay between 180-182 degrees (pointing downward.)

This makes the IK do this in the Mainline...

But after I remove the rotation keyframes to allow the bones to move freely, it looks like this...

The above is more correct, but we probably want the leg to bend the other direction, which is a different issue. To correct this, we need to 'hint' the Thigh bone to bend in that direction, so it looks like this...

To fix this, I made a slight bend in the knee at frame 0, which tells IK to bend the knee in this direction. It's not necessary to 'bend' the artwork to match; the bend is there only to inform the IK. Here's what this looks like...

As you animate the character, you may wish to bend the knee in the other direction. To do this, keyframe the knee rotation to bend the other way, and IK will understand your intention. (It's typically two keyframes near each other: one to hold the pose for the first direction, and a second to transition the bend to the opposite direction.)
Tip: This is just me, but I generally don't use Smart Bones to control the transforms of many bones in my rigs because that can limit the posing possibilities and make performances look mechanical. (Which is fine if that's the intention.)
I suspect there's more to fix here, but I hope this info gives you clues for where to look.
Good luck!
I didn't have time to look deeply, but at a glance, it seems you have many bones, including other smart bones, under the control of GIRO CUERPO. In the image below, Moho is highlighting all the bones controlled by GIRO CUERPO.

I mainly suspect that the rotation of the thigh bone is being 'locked' by the GIRO CUERPO Smart Bone because that's how it's keyframed, and this can make the IK appear to be broken. In other words, the IK is fine, but the Smart Bone is overriding the leg rotation.
My guess is that your intention was to keyframe only the X movement of some bones in the Smart Bone, so you might want to check that.
For example, here in the GIRO CUERPO Smart Bone timeline, I see rotation keys for the Thigh and Shin bones, and the Thigh bone is keyframed to stay between 180-182 degrees (pointing downward.)

This makes the IK do this in the Mainline...

But after I remove the rotation keyframes to allow the bones to move freely, it looks like this...

The above is more correct, but we probably want the leg to bend the other direction, which is a different issue. To correct this, we need to 'hint' the Thigh bone to bend in that direction, so it looks like this...

To fix this, I made a slight bend in the knee at frame 0, which tells IK to bend the knee in this direction. It's not necessary to 'bend' the artwork to match; the bend is there only to inform the IK. Here's what this looks like...

As you animate the character, you may wish to bend the knee in the other direction. To do this, keyframe the knee rotation to bend the other way, and IK will understand your intention. (It's typically two keyframes near each other: one to hold the pose for the first direction, and a second to transition the bend to the opposite direction.)
Tip: This is just me, but I generally don't use Smart Bones to control the transforms of many bones in my rigs because that can limit the posing possibilities and make performances look mechanical. (Which is fine if that's the intention.)
I suspect there's more to fix here, but I hope this info gives you clues for where to look.
Good luck!
Last edited by Greenlaw on Tue Sep 16, 2025 7:12 am, edited 11 times in total.
NEW! Visit our Little Green Dog Channel on YouTube!
D.R. Greenlaw
Artist/Partner - Little Green Dog
Little Green Dog Channel | Greenlaw's Demo Reel Channel
D.R. Greenlaw
Artist/Partner - Little Green Dog
Little Green Dog Channel | Greenlaw's Demo Reel Channel
Re: Issue with ik when character turns
One more tip: it's a good idea to name all your bones. I like to keep the names short and clearly descriptive.
For example, when I name my right leg bones, I typically call them...
Leg Up R
Leg Lo R
Foot R
Leg Tgt R
This may seem like extra work, but it pays off by making editing and troubleshooting rig issues much easier.
For example, when I name my right leg bones, I typically call them...
Leg Up R
Leg Lo R
Foot R
Leg Tgt R
This may seem like extra work, but it pays off by making editing and troubleshooting rig issues much easier.
NEW! Visit our Little Green Dog Channel on YouTube!
D.R. Greenlaw
Artist/Partner - Little Green Dog
Little Green Dog Channel | Greenlaw's Demo Reel Channel
D.R. Greenlaw
Artist/Partner - Little Green Dog
Little Green Dog Channel | Greenlaw's Demo Reel Channel
-
- Posts: 5
- Joined: Sat Jul 19, 2025 4:38 pm
Re: Issue with ik when character turns
Thank you!! Thanks, Greenlaw and Synthsin75, for your super help
! It solved my problem.
By the way, I was wondering if either of you could give me some feedback, corrections in DM on some animations I'm working on, I’ll have them ready in 3–4 weeks and can send them to you if you’d like. Thanks again

By the way, I was wondering if either of you could give me some feedback, corrections in DM on some animations I'm working on, I’ll have them ready in 3–4 weeks and can send them to you if you’d like. Thanks again
- synthsin75
- Posts: 10333
- Joined: Mon Jan 14, 2008 2:20 pm
- Location: Oklahoma
- Contact:
Re: Issue with ik when character turns
Greenlaw is the expert animator, but I'd take a look if you want a second set of eyes.
- Wes
Donations: https://www.paypal.com/paypalme/synthsin75 (Thx, everyone.)
https://www.youtube.com/user/synthsin75
Scripting reference: https://mohoscripting.com/
Donations: https://www.paypal.com/paypalme/synthsin75 (Thx, everyone.)
https://www.youtube.com/user/synthsin75
Scripting reference: https://mohoscripting.com/