Parenting and IK problems!

# 1 25-08-2006 , 12:28 AM

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Join Date: Nov 2005

Location: England

Posts: 102

Hi all,

I have a problem with a scene I'm doing. Basically the green guy is going to be pushing the orange guy back as he's shouting and panicking at him.

The problem is, I'd like the green guy's hands to be locked in some way to the orange guy so I dont have to keep lining his hands up frame by frame. I'm assuming this has something to do with IK in the green guy's arms and parenting them to the orange guy in some way. I've tried parenting the IK handle to various bones on the orange guy but it's not working the way I'd like user added image

Oh and by the way, can anyone tell me why the IK in the green guy's left arm bends the arm in a different way to the right arm's IK?

Here's the link to the file:

https://www.simontaylorfilms.com/maya...2dontpress.zip

Thanks in advance!
Simon

www.simontayloranimation.com

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# 2 25-08-2006 , 01:51 PM

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Join Date: Feb 2005

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Posts: 220

The reason its's probably not working is that joints rotate, they don't translate. I think this is what you're supposed to do... create a couple of locators. put them into the hierarchy, posistioned where you want the hands to be (more or less). Then, point constrain either whatever control curves you're using, or the iks, to these locators (but not parent constrain them). This should keep the distances correct, but keep the ik handles from behaving oddly during rotations. So, when the constraint is at or near 1, the hands will be snapped to the shoulders (minus whatever offset you give them), and at or near 0, the constraint will have no effect, allowing you to make other keys.

As for right and left arms moving differently.... its probably due to the idiosyncracies of the ikSolver.... you have to rotate the arm over 180 degrees. This shouldn't be as bad as it sounds, due to the fact that you'd need to be able to make these adjustments during normal charachter animation anyways. Although you may need to give yourself more control surfaces....

Book Wise

https://X4nd5r.deviantart.com

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# 3 26-08-2006 , 12:25 AM

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Join Date: Nov 2005

Location: England

Posts: 102

Thanks! Will give that a go

Simon :-)

www.simontayloranimation.com

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# 4 03-09-2006 , 09:50 AM

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Join Date: May 2004

Location: Utah, USA

Posts: 369

I think the IK problem with the arm means that the arms are not mirrored; They are not positioned exactly the same. I usually set up the bones for one arm then mirror them over to the other side. You'll find that staying totally symetrical with your models will save you so much time and head-ache in the end. You can break symetry after the model is rigged.

As far as making the hand of one character "stick" to the body of another character; you might try setting up a simple skin cluster on the model's chest then point constrain the other character's arm IK handle. You could also choose a bone or any other object or locator to constrain to as long as you set the constraint to "maintain offset" When you turn off the constraint, the arm IK is free to do what it wants but when you turn it on, it will stick. Now, you don't just want to turn it on . That will cause the IK to "snap" to the chest. You want to keyframe the constraint changing from 0 to 1 over time. You can turn it off when you're ready for the IK to move away through normal keyframing.

I don't want to give you the impression that this is as easy as what I just explained. It requires that your rig is set up properly and that you know how to effectively animate everything but, it will work.

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Parenting and IK problems!

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