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Galakgorr
04-02-2006, 09:08 AM
Hi,

I'm still new to rigging and I'm having an awful time trying to get a control arm / bind arm setup to work. I want IK control with forearm and bicep twist joints in the bind arm, and a "sticky" hand so it keeps its rotation whenever possible. My problem is that the wrist tends to flip around like crazy anytime I move the arm out in front of the body. I've been trying to follow other tutorials I found from forum searches but I couldn't seem to get a straight answer as to what causes this problem and how to fix it. I used dwRiggingTools to try and see if maybe there was something wrong with my skeleton, but that script rigged the arm just fine with my skeleton so I know it's just something with the controls and connections. Any advice? Full tutorials? I've been trying to do this for a long time and I just can't figure it out.

instruct9r
04-02-2006, 07:47 PM
One of the ways is to make you're arm like this one below:

Make a orient contrain from Elbow to Bicep only in the X rotation and from wrist to foreamr..
And it will work... But first Orient youre joints.
The bicep and elbow also the wrist and forearm must have identical orientation of the joints

http://www.geocities.com/instruct9r/ARM.jpg

Galakgorr
04-03-2006, 05:54 PM
Thanks Instruct9r, I think I figured it out. I didn't want to use the setup you listed because I want to be able to eventually use an IK/FK switch, and you need a control arm for that. It turns out that I could prevent the flipping problem at the wrist from happening just by changing the rotate order of the wrist joint and control wrist joint to ZYX instead of XYZ. I'm not entirely sure why it worked but at least it DOES work.

instruct9r
04-03-2006, 09:08 PM
I use this method with IK FK switching and it works fine.

Use this as youre original arm (that will be binded) for the FK and IK arm use only Shoulder, Elbow and Wrist. Make orient contraint from FK shoulder to Original Shoulder and so on and when you rotate the FK or IK arm it Will rotate the original arm and from there the bicep and the Forearm will work fine because they have nothing to do with the FK or IK arm, they just watch for the rotation of the original Elbow and Wrist.

john_homer
04-03-2006, 09:12 PM
Instruct9r is correct.. you will need the extra joints to distribute the twist and get nice deformations.. I would actually recommend 4 rather than only 1..

.j

isoparmB
04-06-2006, 02:55 PM
Instruct9r is correct.. you will need the extra joints to distribute the twist and get nice deformations.. I would actually recommend 4 rather than only 1..

.j


Interesting, so your forearm joints twist in increasing order and you have more joints with varied rotations to distribute the weight over...

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