View Full Version : regarding parent constraints

12 December 2008, 06:16 PM
Hey there, I've got an issue with a rig I'm animating, and instead of waiting forever for the rigger to get back to me I thought I'd run here and see if anybody could help.

It's such a basic problem. I have four leg controls and a root control. I want a parent constraint on the legs to the root so I can key the parent and have them move independently up to a certain point, and then parent to the root and move with it. Simple. Ok, so my problem is once I add the constraint, I can't key the leg controls, everytime I move them and key, they pop back to their original spot.

What am I missing here?

12 December 2008, 09:01 PM
Hey there Michael,

If you want to be able to blend between the foot being parented to the root, and being parented to the world, you need to give the parent constraint a world object.

You can use a node like a locator to do this. When creating your constraint, first select the locator, then the root control, and finally your foot. You will now see in the channel box that your parent constraint has w0 and w1 weight values. Both of them will be set to 1. At this moment the foot control is equally weighted to both, so it will remain halfway between the root and the locator. Set either weight to 1 and the opposing weight to 0 and the foot will move wholly with the root or the locator.

So now you can blend between the world (locator) and the root.

If you want to turn it on/off mid animation, you might have to reposition the locator to 'catch up' with the new position of the root, but I think should be able to figure things out now.

Hope this helps dude :)

12 December 2008, 09:09 PM
Beautiful, just the simple "how come I didn't think of that" solution I was hoping for. Thanks for your help David!

**edit** actually stumbled across an easier method, just grouped the control to itself and applied the parent constraint to the group, not the leg control. Don't know what I didn't think of do it sooner.

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12 December 2008, 09:09 PM
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