​

let bands = [];

​

const minWidth = 10;

const maxWidth = 150;

​

const maxChange = 15;

​

function setup() {

  createCanvas(400, 400);

  colorMode(HSB);

  initBands();

}

​

function draw() {

  let x = 0;

  for(let b = 0; b < bands.length; b ++) {

    const band = bands[b];

    for(let i = 0; i < band.x; i ++) {

      stroke(band.y, 255, 255);

      line(x + i, y, x + i, height);

    }

    x += band.x;

  }

  modifyBands();

  y ++;

}

function modifyBands() {

  let x = 0;

  bands = bands.filter(band => {

    band.x += random(-maxChange, maxChange);

    if(band.x <= 0) {

      return false;

    }

    x += band.x;

    return true;

  });

  while(x < width) {

    const band = newBand();

    x += band.x;

    bands.push(band);

  }

}

​

function initBands() {

  bands = [];

  let x = 0;

  while(x < width) {

    const band = newBand();

    bands.push(band);

    x += band.x;

  }

}

​

function newBand() {

  let w = random(minWidth, maxWidth);

  let h = random(255);

  return createVector(w, h);

}