By DK (Demian) (64.108.72.114) on Saturday, February 08, 2003 - 01:40 pm:

I'm at my wit's end. I cannot seem to figure out how to create an IK rig for a pair of arms. Maybe I'm expecting too much but, nothing I seem to do results in my being able to move an arm in a logical fashion.

I've tried goals and limits and control bones and yelling at the computer and and and...

I will email my model and scene to anyone who can see it in their heart to help my poor ignorant ass.

Much of the time, when moving the arm goals, I seem to be fighting them for position. Why is this? Why can't I just move them around the scene and have the arms follow?

By Will Silver (Lw_Will) (66.27.96.238) on Sunday, February 09, 2003 - 10:17 am:

Okay... not seeing you rig, I can't comment on how you've gone wrong. So... here are some general parameters.

-Remember to only activate the IK motion on all of the bones you want to move. Usually you don't want to move more than two bones in any chain.

-Conversely, remember to activate the "Uneffected by IK" where you want the IK motion to stop. (IE the shoulder where you want the lower two bones to be IK'd)

-Now, here is the single most easy and complex trick I've learned (from BOTH Larry Shultz and Jennifer Hachigian)is to PRE-MOVE the IK bones.

Say, for instance, that you have the lower bone and the upper arm bone. The lower bone will move (at a max) about 90 degrees in pos y... so, you move it 90 degrees. THEN you activate to goal object, snapping the bone back to its original position. Then, if you move the goal, it will naturally want to move in the "pos y" position.

Then, keep goals in reach should stop your struggle ( I know it did for me. ;-) ).

Also, you might want to use ACS4. A great tool for rigging!

Will

By eric smith (Ericsmith) (4.33.33.44) on Monday, February 10, 2003 - 11:09 am:

Have you checked the pivot rotation of the bones before activating IK? What you're describing sounds like it could be gimbal lock. Try doing a record pivot rotation on the bone before making it IK.

Eric

By DK (Demian) (64.108.72.114) on Tuesday, February 11, 2003 - 10:10 am:

Thanks everyone. This all sounds good. I'm quickly realizing that there's no shortcuts to learning IK...

By Fee ... (Phunky_Fee) (217.204.66.43) on Wednesday, February 12, 2003 - 05:23 am:

Check out the "Fast IK" Plug-in

http://www.flay.com/GetDetail.cfm?ID=1521


maybe it will help you get going.