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Cow Update: Tracking a Child Part 1

In this tutorial, I show you how to track the position of a parented layer using expressions in Adobe After Effects. Special thanks to Michael Natkin and Dan Ebberts for sharing their knowledge.

To track the position of a child layer, use this expression on the layer you want to effect.

L = thisComp.layer(”child_layer”);
P = L.toWorld(L.anchorPoint);

where P[0] gives x, P[1] gives y,  and P[2] gives z.

 

  1. efex Apr 8th 2009

    It’s always a great plasure to watch your tutorials! Looking forwared to the second part :)

    (PS: I choose to get the Sony EX3… )

  2. Shawn Romano Apr 8th 2009

    This is SICK! Thanks!

  3. CAMERON Apr 9th 2009

    AMAZING….ABSOLUTELY AMAZING

  4. Carl Apr 9th 2009

    Thanks, Guys.

    It’s always a blast putting the tutorials together.

  5. tishuggah May 10th 2009

    Hey,

    Thanks for the great tutorial.
    I’ve tryed it using trapcode’s particular to make the “the comet tail”. I manage to match te X and Y position for the emitter position, but it didn’t work for the Z position.
    So if some got the same problem, i found the solution!!

    I just put the code (L = thisComp.layer(”child_layer”);
    P = L.toWorld(L.anchorPoint);) on a nul object and than pickwhip the z emitter position to the z anchor point of the nul object! It works.

    Hope that could help someone.

  6. Saad Ali Nov 18th 2009

    thanks to all the members of telescopemedia
    for sharing a lot of knowledge with us.i m crazy about animation,editing and lot of things like this and this is the rite place for me and for all the ppl like me..thanks again.

  7. Ben Feb 11th 2010

    Hi carl,
    Is there a way of adjusting the code to work for scale and rotation as well?

  8. Carl Feb 12th 2010

    Ben –

    I’m thinking it would be possible to adapt Dan Ebbert’s IK expressions for this purpose, but I don’t have a working solution at the moment.

    Here’s the IK code for your reference.

    http://motionscript.com/design-guide/ik.html

    Are you trying to link Particular or Particle World to your child?

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