• Adobe After Effects

  Using the slider control and gradient ramp to only effect the x property (a series of lines)

  Posted by Jo Willard on June 26, 2020 at 1:27 pm

  Hi,

  I’ve stumbled across a really useful tutorial to create a halftone effect using the size controller with a gradient ramp to animate the movement:

  https://www.youtube.com/watch?v=1UaZNcVobhg

  I’d like to do this to a series of lines instead of dots but the slider control just seems to have one control for both x and y axis and not one for one or the other. I only want the width of the line effected and not the length.

  I actually got in contact with Mike the tutor to see if it was a matter of adjusting the expression but I didn’t understand what he sent!

  The expression in the tutorial placed on the shape’s scale property is:
  x = thisComp.layer(“Gradient”).sampleImage(transform.position, [.5,.5]/2, true, time)[0];100*[x,x]

  Mike said adding [0] to the end.

  [0] x property
  [1] y property
  [2] z property

  but end of where? It didn’t work by putting it at the end of the expression.

  Is anyone able to help? Thanks so much for reading my waffle!!!

  Jo

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  Jo Willard replied 6 years, 3 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Graham Quince

  June 27, 2020 at 9:16 am

  Looking at the expression, I think what you’re after is to adjust the X scale, but not the Y scake. Mike used a little bit of a shortcut, which I think is the source of your confusion. If I rewrite the expression, it might be clearer:

  
x = thisComp.layer("Gradient").sampleImage(transform.position, [.5,.5]/2, true, time)[0];
y = x;
100*[x,y];


  If you only want the X scale to be adjust and have y be a fixed scale:

  
x = thisComp.layer("Gradient").sampleImage(transform.position, [.5,.5]/2, true, time)[0];
y = value[1];
100*[x,y];


  This picks up the current . user specified value for Y, but leaves X to be whatever you want. Now Mike has also used a 100*[x,x] in his expression, which might be easier to write as:

  
x = thisComp.layer("Gradient").sampleImage(transform.position, [.5,.5]/2, true, time)[0]*100;
y = value[1];
[x,y];


  This way you’ll only be multiplying X by 100 and leaving Y to the value you set.

  http://www.YouTube.com/ShiveringCactus – After Effects Tutorials
• 

  Jo Willard

  June 27, 2020 at 11:57 am

  Perfect! Thank you so much Graham! I still don’t understand how expressions work and would never have been able to figure this out but you gave me the answer. Appreciate your time.

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