let xpos, ypos;

let oldypos,oldxpos;

let s;

​

let lines = [];

let lineArr = [];

​

function setup() {

  createCanvas(400, 400);

  xval =0;

  xspeed = .0005;

  yval = .5;

  s = 1

}

​

function draw() {

  background(220);

  xval += xspeed;

  xpos = map(xval,0,1,0,width);

  ypos = map(yval,1,0,0,height);

  fill(0);

  ellipse(xpos,ypos,2*s,2*s);

  ellipse(width/2,height/2,10*s,10*s);

  for(let i=0; i< lines.length; i++)

  {

    let curArr = lines[i];

    line(curArr[0],curArr[1],curArr[2],curArr[3]);

  }

  if(random(1) < 0.3)

  {

    yval += random(-0.01,.01);

    lineArr = [oldxpos,oldypos,xpos,ypos];

    lines.push(lineArr);

  }

  oldypos = ypos;

  oldxpos = xpos;

}