Please help. For some reason animation jitters in random ways, sometimes its normal, sometimes its not. And motion path always shows error-like peaks in different places after each update.
This jittering is always inconsistent. And when I bake it it bakes with jittering.
Can it happen because it has different curves rotation keys on different frames?
This happens in Blender 3.6, 4.2.1, 4.3.0.
Hi;
I’d primordially check 2 things:
Dependency Cycles: Toggle System Console < Window < Topbar.
Stacking Transforms
Basically, Stacking Tranforms (e.g., from certain Master Bones in the Skeleton which, like the Hips or Torso Bone, but not the Center of Gravity Bone and probably not the Root Bone) will destroy Arcs of motion. But there are different cases of Stacking Transforms. I’m not referring to Constant type ones (which are simply due to inconsistent Rigging), but to the ones which will only take effect, occasionally, during 3D Animation, because, for example, a Parent Bone of the Mater IK Bone was Posed too far away from a relative/relational, Safe Volume in 3D Space, during a Safe Range of Key Frames.
This demonstration of this effect I’ve made some time ago and it’s not a very clean presentation, but it addresses exactly that mentioned, possible issue, and a way to handle it (I think I’ve set the case of a Jump or some Floating displacement like that as an example near the end of the video).
It could be something else, but I believe it’s that case of Stacking Transforms. They will move the affected Master IK Bone Linearly, and that means you’ll have at least 2 Interpolation F-Curves which Blender will be trying to ‘Mix’ in a completely useless way for most cases of Character Animation, because it is equivalent to ‘inorganic’ mechanical stiff motion (something akin perhaps to 0-Gravity); in other words, it’s pure gargabe, and we need more humane CG Technology for Rigging & Animation.
So, this is why probably you’re getting those strange Motion Paths output in the Viewport.
I’m thinking it’s a cyclic dependency problem. As @Pxy-Gnomes suggests, check blender’s console window for error messages.
Randy
Thank you. I think, that was it. I’ve never seen this error before.
You’re welcome, bro.
Btw, can you just confirm the cause, please? I myself ended up not understanding for sure if it was a Dependency Cycle or the Stacking Transforms case (I interprete it was the first because you mentioned “error” 
).
Thanks!
Yes. It was cycling dependency. Several control bone were copying positions from bones that were in IK chain (I’ve copied those bones carelessly).
Is this best approach? I usually add IK to foot bone. I’m not very good at animation and rigging.
I think there are probably more then one way but i always place the ik on the shin bone.
Here is a tutorial doing it this way: https://www.youtube.com/watch?v=aAE_Az_51sk
The important thing is to unparent the ik control/target bone and add pole
bone.
leg ik.blend (898.1 KB)
