• Adobe After Effects Expressions

  Move random distance along X, hold, then random distance along Y

  Posted by Andre Ash on March 27, 2017 at 6:14 am

  I’m trying to get null to move randomly following a grid. That is; it can only move up, down, left or right at any one time.

  I’d like it to move, stop, then change direction and move again.

  The length of the move would be set to a random distance with a min/max.

  I’ll then be adding a tracer to the null.

  Andre Ash replied 9 years, 5 months ago 1 Member · 2 Replies
• 2 Replies

• 

  Andre Ash

  March 27, 2017 at 6:22 am

  I think I found it

  origin = [10,10]; //upper left hand corner of grid
dimX = 8; //number of columns
dimY = 6; //number of rows
gap = 20; // distance between cells (pixels)
gridRate = 300; //speed (pixels per second)
holdTime = .2; //(seconds)

  end = 0;
  j = 0;

  while (time >= end){
  seedRandom(j,true);
  startX = Math.floor(random(dimX))*gap + origin[0];
  startY = Math.floor(random(dimY))*gap + origin[1];
  j +=1;
  seedRandom(j,true)
  start = end;
  endX = Math.floor(random(dimX))*gap + origin[0];
  endY = Math.floor(random(dimY))*gap + origin[1];
  deltaX = Math.abs(endX - startX);
  deltaY = Math.abs(endY - startY);

  end += (deltaX + deltaY)/gridRate + 2*holdTime;
  }

  p1 = start + deltaX/gridRate;
  p2 = p1 + holdTime;
  p3 = p2 + deltaY/gridRate;

  if (time < p1){
ease(time,start,p1,[startX,startY],[endX,startY])
}else if (time < p2){
[endX,startY]
}else if (time < p3){
ease(time,p2,p3,[endX,startY],[endX,endY])
}else{
[endX,endY]
}

• 

  Andre Ash

  March 27, 2017 at 6:24 am

  As always, it was thanks to Dan.

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