• Adobe After Effects Expressions

  Random Lines Expression

  Posted by David Rodriguez on October 9, 2007 at 4:11 am

  I am using Dan Ebbert’s random lines expression
  https://www.motionscript.com/expressions-lab-ae65/random-lines.html

  how can I change the expression for horizontal bars?
  I cant figure out what part of the expression changes [x,y]

  tMin = .5; //minimum segment duration
  tMax = 2; //maximum segment duration

  end = 0;
  j = 0;
  while (time >= end){
  j++;
  seedRandom(j,true);
  start = end;
  end += random(tMin,tMax);
  }
  endVal = random(thisComp.width);
  seedRandom(j – 1,true);
  x = random(); //this is a throw-away value
  startVal = random()*this_comp.width;
  x = ease(time,start,end,startVal,endVal);
  [x,value[1]]

  David Rodriguez replied 18 years, 10 months ago 2 Members · 4 Replies
• 4 Replies

• 

  Mike Clasby

  October 9, 2007 at 6:15 am

  This seems to work on a horizontal line’s position:

  tMin = .5; //minimum segment duration
  tMax = 2; //maximum segment duration

  end = 0;
  j = 0;
  while (time >= end){
  j++;
  seedRandom(j,true);
  start = end;
  end += random(tMin,tMax);
  }
  endVal = random(thisComp.height);
  seedRandom(j – 1,true);
  y = random(); //this is a throw-away value
  startVal = random()*this_comp.width;
  y = ease(time,start,end,startVal,endVal);
  [value[0], y]

  I just replaced the x’s with y’s (lines 14, 16, and 17). Then in line 17 “value[0]” means use the x value, and their places are reversed since the left side is the x, and where the y is in line 17 is the y value (it was value[1] meaning use the y value).

  Also I changed the “width” in line 12 to “height”, so the lines stay within the screen:

  endVal = random(thisComp.width);

  to

  endVal = random(thisComp.height);

  So in case I was vague above,
  value[0] is the x value
  and value[1] is the y value
  and value[2] is the z value
• 

  David Rodriguez

  October 9, 2007 at 6:29 am

  Thank you so much. This is very close to what I need. For some reason the lines do not stay on screen they go way off the bottom but not the top.

  Thanks for you help
  David
• 

  Mike Clasby

  October 9, 2007 at 7:02 am

  Yikes, I forgot a width to height change on line 15, it should be this:

  startVal = random()*this_comp.height;

  And the whole expression, this:

  tMin = .5; //minimum segment duration
  tMax = 2; //maximum segment duration

  end = 0;
  j = 0;
  while (time >= end){
  j++;
  seedRandom(j,true);
  start = end;
  end += random(tMin,tMax);
  }
  endVal = random(thisComp.height);
  seedRandom(j – 1,true);
  y = random(); //this is a throw-away value
  startVal = random()*this_comp.height;
  y = ease(time,start,end,startVal,endVal);
  [value[0], y]
• 

  David Rodriguez

  October 9, 2007 at 7:26 am

  Thank you, it is perfect!

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