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Pat Reilly

how can you delay rotation from a parent objects?

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I'm new to expressions but, I'm working on a cut out character type of animation for a small web video.

 

So how can I delay a rotation from a parent objects in after effects? Ex - I have a top and lower part of the arm. The lower arm is a child of the top arm. So when I key frame the top arm I want the lower arm to have a delay of 2-3 frames.

 

Here is an example of the type of animation I'm looking at -

http://www.adolescent.tv/website/main.php

CMT / Country Fried Home Videos

 

Thanks!

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The way that would afford you the most control over easing would be to just hand keyframe the lower arms rotation just like you do the top. Just forward kinematics. To simply right an expression for it may not give you the control and subtlety that you want in order to avoid it looking like it was just following an expression. Usually doing something by hand will help you get a more natural or organic feel.

 

if you're looking for a systematic way to get started then you could try this: Set simultaneous keys for the upper and lower arms and then offset the lower arm's keys. Once they are offset you can go in and tweak the easing and timing until they look right.

Edited by SaintEfan

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The way that would afford you the most control over easing would be to just hand keyframe the lower arms rotation just like you do the top. Just forward kinematics. To simply right an expression for it may not give you the control and subtlety that you want in order to avoid it looking like it was just following an expression. Usually doing something by hand will help you get a more natural or organic feel.

 

if you're looking for a systematic way to get started then you could try this: Set simultaneous keys for the upper and lower arms and then offset the lower arm's keys. Once they are offset you can go in and tweak the easing and timing until they look right.

 

thanks for the tip I will give it a shot.

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a very easy way would be to pickwhip the rotation properties of the lower part to it's parent (upper part). This will give you the base expression. Then add: valueAtTime(time-.1)

 

This will cause rotation from the anchor point, .1 seconds after the parent moves. Just find the correct value and you are good to go. Make sure the anchor point is at the joint

 

You could also first add a slider expression to the lower arm and express that to the lower arm rotation. Then add the above expression and you have even more control. Might be too much, but at least the first expression will get you close.

 

If you have any problems, upload your project and I will take a look at it

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a very easy way would be to pickwhip the rotation properties of the lower part to it's parent (upper part). This will give you the base expression. Then add: valueAtTime(time-.1)

 

This will cause rotation from the anchor point, .1 seconds after the parent moves. Just find the correct value and you are good to go. Make sure the anchor point is at the joint

 

You could also first add a slider expression to the lower arm and express that to the lower arm rotation. Then add the above expression and you have even more control. Might be too much, but at least the first expression will get you close.

 

If you have any problems, upload your project and I will take a look at it

Cool I should be done with the vid this week, I'll post it when its live. Thanks for your help!

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