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Activity Forums Adobe After Effects Expressions Making Expressions Relative

• # Making Expressions Relative

Posted by on September 18, 2005 at 5:57 am

Greetings:

So, I am just getting into expressions. I am trying to set the rotation of one layer to the position keyframes of another layer. Just using the default pick-whip expression causes the layer to turn 90 degrees and just sit there. In Motion Math there was a way to make the expession relative How can I modify the expression to do this?

Thanks.

3 Members · 4 Replies
• 4 Replies
• ### Steve Roberts

September 18, 2005 at 6:14 am

If you pickwhip the rotation value of one layer to (say) the Y-position value of another layer, the rotation value will match the position value. The numbers will match. If the position value is 397, the angle will be 397.

So that’s how they work.

If your position values change, your rotational values should change. Given your stated result, I’d say you either used orientation (not rotation) or the position values didn’t change. Not sure though.

What is the result you want? (not the solution or the method)
Is there a range, where if position goes from 0 to 1094, you want the angle to go from 0 to 90?

• ### Larry Winters

September 18, 2005 at 6:34 am

Thanks for responding.

Here’s what I’m trying to do:
I’m making a character animation. I have the character’s lip as one layer. I have key-framed this layer using only position key frames.

This layer is parented to a head a layer. I want to set the head layer’s rotation to the key frames from the lip layer.

I don’t know if this helps, but I am used to using Motion Math in older AE versions. In Motion Math I used the “copy relative values” script to achieve what I want. I think I just need to modify the expression so that it uses relative position/rotation instead of actual position/rotation.

Does this make sense?

• ### Mylenium

September 18, 2005 at 9:18 am

Use the interpolation methods. Something like

This wil remap you linear motion values to rotation values. Just fill in the appropriate values and experiment a little.

Mylenium

[Pour Myl

• ### Larry Winters

September 19, 2005 at 4:58 pm

Hey, thanks. I have not had a chance yet to try this out due to visiting relatives. Hopefully, I will get to it tonight.

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