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Parenting "in place" versus "absolute parenting"

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Eric Chard
Parenting "in place" versus "absolute parenting"
on Jul 2, 2013 at 7:12:00 pm

In Lightwave, it used to be that when you parented an object (actually 'childed', but I lost that war on all fronts, including AE) the object would JUMP if the parent were not at 0/0/0 because the child's origin was now moved.

Obviously this can be inconvenient, and Lightwave has long had a (default) option to 'Parent in Place', which is equivalent to how AE does its parenting.

BUT sometimes you want the old behaviour: is there a way in AE that I can parent a layer to another and have the child jump to the Anchor Point of the parent layer?

Tnx!

++++++++++++++++
"Putting the HARM in 'harmonica' since 2005."
++++++++++++++++


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Kevin Camp
Re: Parenting "in place" versus "absolute parenting"
on Jul 2, 2013 at 7:49:42 pm

try this expression:

if (hasParent == true) position+parent.position else value;

it should make the position value of the child relative to the position of the parent (if parented).

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Eric Chard
Re: Parenting "in place" versus "absolute parenting"
on Jul 2, 2013 at 8:17:45 pm

Kevin, thanks so much, but TMK that doesn't work. (see attached, green square.)

I think an expression would have to reference the Anchor Point of the layer in question. The Position channel has been automagically offset by Pan Behind to give the illusion of the parent (gray) not moving.... although it would seem that.. that .... I got nuthin'.

6216_anchorpointexerciseexpression.zip

++++++++++++++++
"Putting the HARM in 'harmonica' since 2005."
++++++++++++++++


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Kevin Camp
Re: Parenting "in place" versus "absolute parenting"
on Jul 3, 2013 at 1:01:25 pm

sorry eric, i can't open the file (cs5 here)...

it does appear to work in a very simple set up i made using the pan behind tool to animate the anchor point and position of a layer and then parent another layer to it. it seems to be erratic if i try to re-zero the child layer while parented, but if i un-parent, zero it, and then re-parent it seems to be fine... however it falls apart in other areas as i work with it a bit.

do you need parenting? or would it be fine to simply link the position property of on layer to the position property of another?

something like this:

L = thisComp.layer("Gray Solid"); // name of your layer in quotes
value + L.position


Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Eric Chard
Re: Parenting "in place" versus "absolute parenting"
on Jul 3, 2013 at 11:28:14 pm

Kevin, thanks for the time you've spent on this-- it's really just an exercise I set for myself, so nothing's at stake except education.

If I had to do this (for pay), I'd probably go for expressions. I would have expected linking the Anchor Point of the layer to the 2nd child would work, but off hand I'm not sure what screen coords the anchor point coords correspond to.

I attach an AE7 version so you can see what I'm goofing around with.

'Parent in Place' in LW also complicates things, compared to the old simple minded way of doing things. It's nice that in LW you can revert to the old methods if it simplifies the setup. That'd be a swell feature for AE also: 'Absolute Parenting', i.e., without spatial compensation. (Scarcely worth implementing though.)

Thanks again for looking into this!

6229_anchorpointae7.zip

++++++++++++++++
"Putting the HARM in 'harmonica' since 2005."
++++++++++++++++


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Eric Chard
Re: Parenting "in place" versus "absolute parenting"
on Jul 2, 2013 at 7:49:45 pm

Like this: the blue child square should follow the Anchor Point around the gray square, but it does not. (I'm sure it's doing what it's mathematically SUPPOSED to do, but not what I'd like it to do.)

6215_anchorpointexercise.zip

++++++++++++++++
"Putting the HARM in 'harmonica' since 2005."
++++++++++++++++


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John Cuevas
Re: Parenting "in place" versus "absolute parenting"
on Jul 3, 2013 at 4:13:01 pm

Like this? 6225_anchorpointexercisev2.aep.zip

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.


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