View Full Version : JamSession Huntress Arms Maya 7.0

01 January 2007, 08:54 PM
I am going to focus on the twist for the arms. Try different things to get the ulna radius twist to work soundly and smoothly and to get a slight twist up the upper arm.

I am also going to script in an ik - fk and fk - ik button with no popping or blending, just a simple press of a button.

01 January 2007, 04:49 PM
Interesting approach to the bicepts! Using spline IK to make the muscle bulge. That's a great idea. What exactly are you doing about the radius ulna twist?

01 January 2007, 05:11 PM
For the radius ulna twist, I have 3 bones running down the lower arm. These joints are being controlled by an expression ie.

lf_Twist01.rotateX = lf_wrist02.rotateX * .3;
lf_Twist02.rotateX = lf_wrist02.rotateX * .6;
lf_Twist03.rotateX = lf_wrist02.rotateX * .9;

not the exact expression, but should give you an idea of how they fall off.

I am using blendshapes to control the bulge. The spline IK is to help with upper arm rotations like a ball socket, and it should help smooth out the shoulder area from abrubt angles.

01 January 2007, 10:04 PM

Here is my fk - ik test. I didn't bother painting weights yet, because I like to get all the controls and expressions working correctly before I spend time weighting.

I wrote a script that matches IK 2 FK and it matches FK - IK with a simple click.

For some reason the wrist pops, which I am currently debugging and trying to figure why everything but the wrist works.

Jared's FK 2 IK rig Arm Test (

01 January 2007, 05:56 PM
Unfotunately I am not as familiar with Maya, yet I can tell about a good way I make wrist twist bones in Max. Basically I use 2 point helpers and one expose transform helper. I use the exoseTM helper to see the offset of the wrist bone from the main arm bone, have a set of 3 bones, that represent the wrist, wired to the Exposed Node twist rotation axis through the ExposeTM helper, and then set the wire values to *0.5. That makes each bone rotate a little more then its parent, creating an excellent twist effect. I'll post the screenshots when I'll have access to my PC.

01 January 2007, 12:32 AM
Results are looking good JamSession! More more! :bounce:

In case it's not due to skin weights, the forearm seems to be moving a little too much with the wrist twist. Maybe you wana check that out.

01 January 2007, 01:16 AM
Hey! Its looking good so far! nice model too. but any ways i was wondering how you got the fk-ik button? (or is that classfied?) :-D I'm working on my own rig for advance character rigging and need to create that. any help would be appreciated

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01 January 2007, 01:16 AM
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