let particleSystem = [];

​

​

function setup() {

  createCanvas(400, 400);

  colorMode(HSB);

}

​

function draw() {

  background(220);

  //create a new particle object

  let particle = new Particle();

  //put new object into array

  particleSystem.push(particle);

​

  //for every particle in the array, draw it, move it, and check if it needs to be removed

  for(let p in particleSystem){

    particleSystem[p].draw();

    particleSystem[p].move();

    //if checkAlive function returns false, take out particle

    if(!particleSystem[p].checkAlive()){

      particleSystem.splice(p,1);

    }

  }

}

​

class Particle {

  constructor(){

    //position

    this.x = random(width);

    this.y = random(height);

    //speed

    this.vx = random(-2,2);

    this.vy = random(-2,2);

    //color, using HSB mode!

    this.hue = random(360);

    this.c = color(this.hue,100,100);

    //life span

    this.alive = true;

  }

  //displays particle on screen

  draw(){

    this.c = color(this.hue, 100, 100);

    fill(this.c);

    noStroke();

    ellipse(this.x,this.y,20,20);

  }

  //adjusts position

  move(){

    this.x += this.vx;

    this.y += this.vy;

   // this.brightness += 0.5;

​

  }

  //checks if particle has hit edge of screen, returns true if it hasn't, returns false if it has

  checkAlive(){

    if(this.x > width || this.x < 0){

      this.alive = false;

    }

    if(this.y >height || this.y <0){

      this.alive = false;

    }

    return this.alive; 

  }

}