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View Full Version : IK joint rotation/ik deformation problem


JesseDavis
12-30-2004, 10:33 AM
Hi all. I think this could be a common problem for beginners, and I've done extensive searching on the topic, but here it goes anyways.

In short, how do I change the way the IK handles rotate the joints without effecting an attached skin?

In long,
So I setup my rig, and character, did the skinning, and setup all the controls. I am now doing my IK setup for the arms (Gnomon seems to say that you can do IK after you skin or before, doesn't matter.) Here is the setup so far:

www.digital-infusion.com/ftp/1.jpg (http://www.digital-infusion.com/ftp/1.jpg)

However when I add an Ik handle to it, and move it, it does this:

www.digital-infusion.com/ftp/2.jpg (http://www.digital-infusion.com/ftp/2.jpg)[/url]

Obviously an elbow isn't supposed to bend down, but on the (in this case) z axis. So when I try to adjust for it by rotating the pole vector of the IK handle, it screws up the mesh (and doesn't achieve the results anyways):

[url="http://www.digital-infusion.com/ftp/3.jpg"]www.digital-infusion.com/ftp/3.jpg (http://www.digital-infusion.com/ftp/1.jpg)

So I was wondering what I can do to fix this, other than rejointing and reskinning the entire bloody thing. I know that I can use the copy skin weights thing (which works whether people think it does or not), but will screw a lot of other things up.

Thank you.

poly-phobic
12-30-2004, 02:54 PM
u can delete the ik, and teak your local rotation axis of the elbow to rotate in the proper direction, i would assume it would rotate in the -x direction looking at your 90 degrees are set up there.
and be sure to set a prefered angle before you apply your ik handle since u placed the joints in a straight line.

JesseDavis
12-30-2004, 10:37 PM
ya that's the thing, the joints aren't in a straight line. Should I align them manually (and therefore lose the skinning weights?) or would rotating the joint pivot fix it. (i have a feeling that will alter the mesh as well) I'll try it and see what happens. Thank you for responding.

JesseDavis
12-30-2004, 11:12 PM
well, i just ended up deleteing the joints, copying the previous skin weights, and now I have to clean it all up again. But at least the arms work.

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