View Full Version : rest position - parent constraints - the animators workflow?

07 July 2007, 09:39 AM
hey all
I'm getting a little confuse with maya at the mo when it comes to animating - I'm trying to get my head around using the rest position but I just cant seem to suss out the workflow. either that or its simply not working.

The animation I had was the character running, getting an object (a stickymine) off his hip in his hand then running past a wall and sticking it to a wall.
my prob is I just cant seem to get a nice clean workflow - the only way I could sort it out was 3 locators which the object is parent constrained to and I animate the weight of each one in turn but my prob comes when I'm trying to get it to stay in one position on the hip, then the character picks it up and it is in another position in his hand and finally a third position on the wall.

I thought the rest position was meant to sort this out so its in one rotation position on the hip, then a second position in the hand and finally a third position on the wall. I thought ah if I use the rest position at those points it would hold that position but instead i just find the stickymine completely ignoring it and resting back on the hip.

I'm really stuck here its confusing the hell out of me as theres a weight attribute beneath the parentConstraint node, a blendparent extra attribute and then the rest position - I'm really not sure how they all work together.


07 July 2007, 11:20 AM
I don`t quite understand what`s the problem. The trick is exactly this - select the first, second and third locator and finally the object and parent constraint it. After that you have to animate the weights of the parent constraints first the hip one to 1 and the rest to 0 and 0 and ...etc..

07 July 2007, 11:28 AM
my prob comes if the stickymine I have needs to move or rotate off the point where I parent constrained it to the locators on the various parts of the body and on the wall. If I animate the weights then it works fine but the rotation that was fine for the placement on the utility belt/hip area isn't right for the position in the hand so I rotate and shift the object slightly but as soon as I move on the timeline it snaps back to its original rotation from the hip area. I thought rest position was meant to solve this but it doesn't and I'm just not sure where I'm going wrong.
I had a groupNode above the stickymine that I use then I rotate the mine and position it off the groupNode but i'm sure theres a more effective solution using the constraints.

07 July 2007, 12:31 PM
Well in that case it`s a little tricky thing to do. What I do is building a script for these kind of things wich must do the following:

You have a transfrom on top of the object you need to move /let`s say it`s a sword/
so you build the hierarchy like this:


and parent constraint to the Loc, instead of the object directly

Then the script has to:
1. unparent the Sword_obj /parent it to the world/
2. change the weights of the constraints
3.parent the Sword_obj back to the Sword_loc

That will make the sword stays in the position where you left it.

parent -w Sword_obj;
setAttr "Sword_loc_parentConstraint1.Wall_locW0" 0;
setAttr "Sword_loc_parentConstraint1.Hips_locW1" 1;
setAttr "Sword_loc_parentConstraint1.Hand_locW2" 0;
parent Sword_obj Sword_loc;

Hope that helps.

07 July 2007, 12:54 PM
ant, have you had a look at Hamish McKenzie's zooToolbox (specifically zooCST) ( He has developed a nice system for "space switching". It uses constraints and animated weights as described above, but it makes it possible to easily switch an object from one constraint to another, using a simple right-mouse-button menu, while maintaining the orientation of the object and setting keys.

Here's a quote from the help file: It should be noted that space switching can be used on absolutely anything. I've used it to great effect for prop animation (setting up a prop with multiple dynamic parents makes picking up and putting down props dead simple to animate), on custom rigs, or anywhere else dynamic, easily animated parenting is needed.

The zooTools may look a bit daunting at first, because there are so many of them, but they are well written and worth the effort to learn. Once you figure them out they can save hours of rigging time.

-- David

07 July 2007, 01:23 PM
thanks team - downloaded em now and will have a fiddle tonight ...once I dry out!! (I hate the british climate)

scroll_lock thanks for that little script and technique mate I think I'm doing something similar with the GRP node above the object but I'm having to set everything manually :/ seems to be the only way that I feel confident that maya will do what I ask of it lol (parented more than 100 piston parts to separate locators manually yday evening after me wing chun class lol.... manual manual manual!)

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07 July 2007, 01:23 PM
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