View Full Version : Moving a constraint and chain together

07 July 2010, 05:01 AM
I have gotten myself all confused trying to do this, I thought I would ask for help.

I created a palm tree (to be referenced into another scene) and decided I wanted to have it sway a little. Seemingly simple enough, I built a joint chain (9 or so total) right up the trunk (which is not straight). I created an IK Handle on the whole chain, smooth skinned it and it works properly. Yay.

So I made a nurbs circle for a handle, put it above the tree and used a point constraint from it to the IK Handle. That works, double Yay.

That is, it all worked fine until I referenced it into the scene and tried to move it from 0,0,0. I selected my root joint and moved the tree, the top stayed back underneath the circle. Yup, the circle was still a child of the world.

I have tried numerous ways to fix this (in the original file it is reproducible, the issue is not related to referencing). In my last iteration I have the joint chain and effector in one heirarchy, the tree trunk, fronds, IK Handle and my nurbs circle all grouped as a set.

I would have thought that would cure it. No, I can only manage to move this by selecting both the root joint and the nurbs circle and move them to their new location at the same time (or otherwise the tree top stays back where it started at.

So how would I place the nurbs circle in a hierarchy such that it stayed above the root when I relocate the tree (by moving the root)?

I am not in a panic, because my workaround works, for now. But I know it isn't right because I did something similar in a character by parenting a nurbs circle to a head and constraining each eye to it (an aim constraint was used there). It works as expected, I place it out in front and when the character walks, it moves on. I relocate it to one side, and the eyes follow.

<* Wes *>

I solved this (in my sleep, I think). The solution problem was that my 'root' was a part of the IK chain, when I put the handle into the hierarchy, it makes a sort of loop, where the handle is moved by the root, and the root is rotated by the IK, and that moves the handle and so on.

The simple solution was to rename the root joint, make a new root joint, and parent the old root and the handle to it.

07 July 2010, 03:27 PM
you can use any object you want to do this..

ie this works just as well. Because you are moving everything as a whole. Not that I wrote a tutorial ( or anything on the subject (

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07 July 2010, 03:27 PM
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