Answered

IK Twists bones while FK does not, but can not modify FK

Anonymous 3 months ago updated 3 months ago 4

Hi,

As the title states, when using IK it causes the shoulder bones to twist during the animation, while if I leave it on FK, then the bones are not twisting.

I would like to modify this animation slightly, but given the twisting when trying to use IK, it doesn't appear that I am able to since FK isn't letting me modify all of the transforms?

No Twist:

https://gfycat.com/hauntingthoughtfulalpinegoat

Twist:

https://gfycat.com/oldsecretcanary

UMotion Version:
1.22p06
Unity Version:
2019.4.3f1

Answer

Answer
Answered

Hi,
thank you very much for your support request.

You can control the twist (i.e. the pole rotation) using the pole handle (the wired sphere near the elbow). In the gif you can see that the pole handle orbits around the arm causing it to twist. If you keep the pole handle at the desired place, there should be no twisting happening.

Please let me know in case you have any follow-up questions.

Best regards,
Peter

Answer
Answered

Hi,
thank you very much for your support request.

You can control the twist (i.e. the pole rotation) using the pole handle (the wired sphere near the elbow). In the gif you can see that the pole handle orbits around the arm causing it to twist. If you keep the pole handle at the desired place, there should be no twisting happening.

Please let me know in case you have any follow-up questions.

Best regards,
Peter

Is there a way to "lock" it, or do I need to use the move tool and readjust it during each key frame that it is off?

The pole target can be keyed like any other object. So if you e.g. only create one key for its position at the first frame, it is going to maintain its position for the whole animation. In your case, you probably just want to delete the keys that you don't need.

Best regards,
Peter

Awesome, I will do that then. Thank you very much!