• Adobe After Effects Expressions

  Expression Help, Shifting Position

  Posted by Byron Purvis on April 13, 2008 at 10:03 am

  I was using one of Andrew Kramer’s tutorials on creating a light saber effect. I got all the way through keyframing my shot and realized that I should not have moved the white solid layer to position the start of light saber effect, since my solid’s edges now don’t line up with the composition when it gets close to the edges. Ugg… then I thought, but HEY an expression might work to fix it!

  I just need to subtract the x & y keyframe values with the amount of pixels that I moved the white solid back into position. My original position was at 1328,640. Now it’s back to 960,540 for a difference of 368,100.

  I tried just making an expression with a -368 and -100, but that didn’t work. I really don’t understand the expression system yet, but I will eventually 🙂 Anyone know what I would need to plug into an expression to shift my keyframes left 368 and up 100?

  Thanks in advance!

  Byron Purvis replied 18 years, 2 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Filip Vandueren

  April 13, 2008 at 2:57 pm

  hi,

  2D position values are decribed as an array: [x,y]
  what you need is this expression:

  
value-[36,100];


  meaning simply: take the current value and subtract the value of [36,100].
• 

  Byron Purvis

  April 13, 2008 at 11:14 pm

  Sweet, worked like a charm! I ended up having to add those values instead of subtracting, but it works now! Thanks a bunch 🙂

  Now it’s time for me to dig into that PDF guide on the install disk 😉

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