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Position Expression for Puppet Strings

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Adam Palmer
Position Expression for Puppet Strings
on Jan 21, 2011 at 11:25:09 am

Hi Guys,

I'm creating a marionette style puppet for a project I'm working on, and I'm finding it hard to find a way to make the strings follow the hands position, not the rotation, without key framing along with the movement.

I have Null objects as controllers for the limbs, and would like the strings to follow only their position so that they are always rotated to the top.

If this isn't the easiest way, if there is a way to parent the layers, and then some kind of way to stop it following, or counteract the rotation with the same effect, that would be equally as good.

Thanks


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Kevin Camp
Re: Position Expression for Puppet Strings
on Jan 21, 2011 at 10:07:27 pm

[Adam Palmer] "I'm finding it hard to find a way to make the strings follow the hands position, not the rotation"

so it sounds like you tried parenting the string layers to the hands, or to the nulls that the hands were parented to... and you then found that rotation properties were also 'parented'.

a simple way to parent just the position property of the strings is to select a null and a string that you want to link together and type 'p' to show the position properties of both (it will be helpful if you can see both properties in the timeline)

select the position property of the string and choose animation>add expression. this will add an expression field, but also add a few controls to the right of the position property. one is the expression pickwhip, that looks a lot like the parenting pickwhip.

click that pickwhip and drag it to the null's position property (make sure it's to the position property, not the null's layer name).

this should add an expression to the expression field that looks something like this:

thisComp.layer('Null 1').transform.position

the string should now follow the null, however it's anchor point will be aligned with the null's anchor, and the anchor point of the string may not be at the end point of the string... to fix that, adjust the string's anchor point property to be near the end that should be attached to the hand.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Adam Palmer
Re: Position Expression for Puppet Strings
on Jan 22, 2011 at 1:19:51 pm

Thanks Kevin,

I feel like such a fool! I'd tried the pickwhip before, but had always pickwhipped the layer rather than the property!

School boy error!

Thanks

Adam


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