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Parenting Position Retaining Orig Position of Child
I’ve search for a reference to this specific question for quite a bit of time. I seems rudimentary, but I would love some closure.
I have to objects on a comp (layer “A” and layer “B”)- I would like to use an expression to parent the position of the one to the other (A as parent, B as child). I’ve been unable to find an expression that does not change the original position of B when entering the expression.
It either places B directly at the same position as A with this expression
thisComp.layer(“A”).transform.position
or displaces B to a different position using this expression
L = thisComp.layer(“A”);
fromWorld(L.toWorld(L.thisComp.layer(“A”).position))Both of course then allow B to then follow A’s position, but I’m curious if there is a way to have B remain its orig position.
My work around has been to add +value to the expression and move B back to its orig position.
Any help would be greatly appreciated.
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5 Replies
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One way to do it is to add layer B’s current position to the amount that Layer A has moved since time zero:
p = thisComp.layer(“A”).transform.position;
value + p – p.valueAtTime(0)This won’t do anything until you actually animate layer A’s position though.
Dan
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Thanks Dan! Works Great!
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Thank you Dan! I was looking for this answer for years.
I am trying to add a delay on this expression but is not working. Should I add at the end on valueAtTime(0)?Thank you!
Gus -
It would depend on what you’re doing exactly, but this would be my guess:
delay = .25;
p = thisComp.layer(“A”).transform.position;
value + p.valueAtTime(time-delay) – p.valueAtTime(0)Dan
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YES! Perfect!
Thank you Dan!
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