movable elbow joints

I have seen many rigs where the elbow joint can slide up and down the hand.  And I wanted to try this on my hand rig, while still being able to keep it Bendy. Apart form this, I wanted a automation control, where the elbow can be moved to any place, and then by adjusting a BEND variable, one could control the curvature of the bend.

I dint spend a lot of time online doing this research. I instead wanted to try this out on my own. I have no idea how the others do it in their rigs. But mine is just a simple combination of constraints. And the bend is controlled procedurally to make the rig respond faster.

Here are the tests:

basic joint structure, with the joints inbetween being used to bend the arms.

 

Move the elbow to any position. notice that the inBetween joints have oriented to move in the correct direction.

 

2 separate attributes on the NURBS circle controls the curvature of the bend in the correct orientation to give a smooth curve.

 

We can now get a smooth curve from shoulder to wrist, or get a S curve, or bend and deform these two regions independent of the other.

 

 

Recap:

– So, I now have an arm where I can move the elbow to any location I want.

– By controlling attributes, I can choose to keep the arm straight, or apply different curvature to it.

 

I have been working primarily with FK.. I should next try the same setup on an FK/IK arm.

and while I am at it, also do an IK/FK snap and see if all this still works.

and finally, to scale the entire rig and test.

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