//https://www.youtube.com/watch?v=T-HGdc8L-7w&list=PLRqwX-V7Uu6Zy51Q-x9tMWIv9cueOFTFA&index=24

​

let balls = [];

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  //BALLS

  for (let i = 0; i < balls.length; i++) {

    balls[i].rollover(mouseX, mouseY);

    balls[i].show();

    balls[i].move(); //update position

  }

  //TITLE

  fill(0);

  textSize(24);

  textAlign(CENTER);

  text("Click empty space to add balls!", width / 2, 50);

  text("Left-click a ball to clone it!", width / 2, 75);

  text("Right-click a ball to remove it!", width / 2, 100);

}

​

function mousePressed() {

  let hits = [];

​

  //in hits, store indices of balls hit by click

  for (let i = 0; i < balls.length; i++) { 

    if (balls[i].isCover(mouseX, mouseY)) {

      hits.push(i);

    }

  }

​

  //if there are hits, clone or remove depending on button

  if (hits.length > 0) {

    if (mouseButton === LEFT) {

      for (let i = 0; i < hits.length; i++) {

        balls.push(balls[hits[i]].clone());

      }

    }

    else if (mouseButton === RIGHT) {

      //loop backwards since, e.g.

      //removing b from [a, b, c] changes index of c

      //but doesn't change index of a

      for (let i = hits.length - 1; i >= 0; i--) {

        balls.splice(hits[i], 1);

      }

    }

  }

  //else, create new ball

  else {

    let r, g, b, a, ballFill;

    r = random(0, 255);

    g = random(0, 255);

    b = random(0, 255);

    a = random(0, 255);

    ballFill = color(r, g, b, a);

​

    balls.push(new Ball(ballFill, mouseX, mouseY));

  }

}