Twist bones don't move with HI IK w/ file

[Anonymous]

Hi I made a biped with some twist bones and a snapshot of it so I can customize it from "scratch." I added an HI IK and controller to the leg but when I rotate it the twist bones don't seem to follow. Any help?

The twist bones are the grayed out bones inside the limbs.

File link https://drive.google.com/file/d/11Z3QSoqVL03iqi5B5sPnFE3dJB_4Q3iN/view?usp=sharing 

[Anonymous]

I figured out. Just had to link each twist bone to the hand. Since the IK is attached to the hand, they all follow the hand. 

[ads_royje]

Hi again @Anonymous !

Thanks for your file!

As the rig is a Snapshot of Biped, it has the same hierarchy.

The biped twist bones are child of their respective body part's parent, they are siblings.

This setup can work, but would require advanced scripting, This is done in code in biped.

In your current rig, I would suggest to start with a simpler setup.
First, parent the twist bones so they have they are child of their respective body parts; for instance the upper arm twist bone to be child of the upperarm, etc.
See in Max in attached video: Hierarchy_setTwistBonesHierarchy.mp4

To setup the twist bones, I would suggest to follow this tutorial:
https://area.autodesk.com/tutorials/3ds-max-rigging-a-character-roll-bones-part-14/
In that tutorial, the rig setup is similar and explains in great detail how to setup both the upperarm (shoulder) and the lowerarm (wrist) twist bones.

Let me know if that helps or not!
Regards, 

[Anonymous]

Thank you, this is exactly what I needed. I will follow that tutorial and let you know how it goes.

[Anonymous]

Thanks once again, @ads_royje. I am close to being finished, I am working on the wrist bone. Only issue now is that he creates a LookAt Constraint for the forearm roll bone and links it to the *wrist* bone, but I don't seem to have one of those and I didn't see the setting to make one in the options for the biped. I tried constraining it to the hand itself, the controller, and the HI IK crosshairs but it wouldn't give me the same effect he got at 5:30. https://drive.google.com/file/d/1APYUAqFowB5u-d5dkahqlaFbAEDdrJ8X/view?usp=sharing

[ads_royje · Accepted solution]

Hi again @Anonymous  !

Thanks for your file! 🙂

Ha yes I see! A few small differences in the hand/wrist part.

As you saw, the wrist and hand bones can be considered as similar. In the tutorial video the hierarchy is a little more complex indeed.

The principals are the same.
One thing that is not mentioned is the roll bone hierarchy, yes hierarchy again! Hierarchy is very important in animation and rigging! 🙂
I this case, the roll bones comes from a biped rig, and again, these have the biped hierarchy. Usable but requires a little more work.
What to do:
All the forearm roll bones to be child of the forearm directly, so one does not influence another.
The roll bone close the hand, has a Look At constraint to the hand (the wrist in the video) and uses the Hand as an up node. It is the up node feature that makes the roll bone follow the hand rotation on a single axis.
The middle roll bone has the Orientation constraint, in the tutorial video it is constraint to the wrist bone, in your rig that would the Hand bone. But as the roll bone near the hand already follows the Hand, we can use that one instead of the hand (wrist bone). The middle roll bone is also Orientation constraint to the forearm bone (half and half between Hand and Forearm).

Now, when rotating the Hand controller (Circle006), both roll bones will follow the Hand.
See in your file in Max: https://autode.sk/35ZStIM

I hope I explained clear enough to get you going!
Let me know how

[Anonymous]

You're a legend. You've saved me probably a couple days if not weeks of google searching for such a simple solution with your thorough videos (and I don't mind the length of them at all). Thank you.

[ads_royje]

Thank you for your generous feedback! 😄