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New here.

I've been implementing some basic IK stuff for a rig of mine. The arms, the legs, etc. Overall I'm happy with how it's been going, but there is a problem.

Whenever I go to push the rig's arms into a more complicated position (in this case, a casual "hands on hips" sort of pose) I end up with some very twisty deformation at the wrists and shoulders.

enter image description here

enter image description here

There's an option to "preserve volume" for the mesh on the armature modifier, and that would be a decent enough band-aid except I need to export the model into Unreal Engine, which won't accept modifiers.

I think this might be a common issue for newbs like me, but I haven't found a clear solution online yet. Hopefully someone here has some suggestions! Any help is appreciated.

EDIT: Here's a PasteAll link to the .blend file if anyone wants to take a direct look: Blend File Link.

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For the elbow, it looks like your arm is pivoting on itself. Think of like a rope you hold tight with one hand and you twist with your other hand. It's what's happening here.
A solution for that would be to lock the bone's rotation on its Y axis. Either through a Limit Rotation constraint, either in the bone's Inverse Kinematics panel:
demo pic

Otherwise, understand that bones do only one thing: rotating vertices around. The "preserve volume" does help to keep the volumes, but it doesn't do any miracles. When two bones rotate on each other, there's always a point when some vertices go the wrong way.

And that's why we use "Corrective Shape Keys". Just make some of those and you will be fine. Also, there are some addons out there (like that one) that might help you create your CSP faster. But start manually, so that you learn how it works and understand how everything works.

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  • $\begingroup$ Took me a minute to find the right configuration, but I think it's looking good! Thank you for your help! $\endgroup$ – Cinebeast Dec 14 '18 at 17:46

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