• Adobe After Effects Expressions

  Expressions Noob-Using null to drive y position of a layer

  Posted by Brian T prairie on March 17, 2013 at 3:50 pm

  I am just starting to teach myself expressions.

  I am rigging a scene and want to use a null with a slider to drive just the y position of another layer. I’m not really sure where to start.

  Any advice would be much appreciated.

  Thanks, Brian.

  Brian T prairie replied 13 years, 5 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Paul Roper

  March 18, 2013 at 12:24 pm

  Select your null layer, and add an expression slider by choosing Effect > Expression Controls > Slider Control.

  In your timeline, open up the null layer to show this expression slider control.

  Select your other layer. Press p to show the Position. Right-click the word Position and choose ‘Separate Dimensions’. It will now show the x and y (and z if it’s a 3D layer) separately.

  alt-click on the stopwatch next to ‘Y Position’. An expression will appear. While the text in the expression is still highlighted, drag the pick-whip (the little spiral thing) onto the word ‘Slider’ on the null layer. This will replace that expression text with text describing the null layer’s slider expression. Press Enter (not Return) to confirm the expression. Drag your slider around to see the other layer move.

  That’s it.

  – Paul
• 

  Brian T prairie

  March 18, 2013 at 7:50 pm

  Thanks Paul. That did the trick. Much appreciated!

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