-
What does this expression do?
This expression, from YT “Create Particles Along A Path”, makes a CC Particle world emitter follow the keyframes of a Null Layer:
target = thisComp.layer(“Null”);
(target.positions[0]-(thisComp.width/2))/thisComp.widthWhat’s all that jazz in the 2nd line about? I can’t parse it: does it have something to do with CC Particle emitters being registered at the center of the comp instead of the upper left? (I think I’m close, but I don’t get it….)
Thnx for any enlightenment.
-
2 Replies
-
That’s because the Particle World Producer property expects its X coordinate (in this example) to be a percentage of comp width relative to the comp center. So the the second line of the expression calculates how far the null’s x position is from the x position of the comp center and divides that by the comp width to get a normalized value between -.5 and +.5.
-
Ahhh! PERCENTAGE of comp width! ::the light dawns::
Thank you, Mister Ebberts!
Reply to this Discussion! Login or Sign Up