I'm trying to work out this shoulder deformation. I can't figure it out.

enter image description here

Is there anything wrong in my armature?

Should i add bones and keep more control of my mesh or use shape keys?

Here is my file blend.


First there should be a twist on the upper arm - so when the arm is rotated like that the twisting is distributed in the upper arm and not in the shoulder joint.

enter image description here

There are 3 bones in the upper arm

  • a control bone that the animator interacts with - the one with custom shape - goes through the whole upper arm. Has no deforms.

  • 2 segment bones both parented to the control bone. The one closer to the shoulder has Copy Rotation turned off and a Damped Track constraint to the second segment bone

The twisting is done with blending bone weights between both segment bones.

The setup of twist is the same for FK rigs, IK rigs, and when there is FK/IK switching it's best to make it on the deform bones.

Second the motion of lifting the arm up is combined of raising the upper arm and the collar bone. The upper arm can lift about only horizontally, then the collar bone takes over and the whole shoulder raises. The lower the arm is the more the raising is done with the upper arm. As the arm goes higher, more movement is done with the collar bone. Having a smooth transition in both rotations is important for it to look natural.

enter image description here

CC attribution: www.sintel.org, model by Angela Guenette, rig by Nathan Vegdahl

  • $\begingroup$ Sorry I'm trying to create the twist on the upper arm but i can't find the way on blender. Can you give me an advice please? $\endgroup$
    – Fuboski
    Nov 17 '15 at 11:35
  • $\begingroup$ @Fuboski Sure, pls explain what you struggle with - is it blending the bone weights?. You can also ask a new question if it's worth it. $\endgroup$ Nov 17 '15 at 12:55
  • $\begingroup$ Can you further elaborate on the bones setup? I'm confused as to how to setup the constraints. Or could you upload an example blend file with this rig set up? $\endgroup$
    – CPLTarun
    Mar 29 '18 at 1:52
  • $\begingroup$ @CPLTarun You can study and download the rig here: blendswap.com/blends/view/7093. $\endgroup$ Mar 29 '18 at 8:57
  • $\begingroup$ That rig is a bit of a confused mess, I can't make heads or tails of it. $\endgroup$ Dec 20 '20 at 19:29

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