let spin = false;

​

// circle class

class Circle {

  constructor(x, y, size) {

    this.x = x;

    this.y = y;

    this.size = size;

    this.fill = color(random(255), random(255), random(255), 150);

    this.speedX = random(-5, 5);

    this.speedY = random(-5, 5);

    this.angle = 0;

  }

  //   display the circles

  display() {

    fill(this.fill);

    ellipse(this.x, this.y, this.size, this.size);

  }

  //  move the circles

  move() {

    //     change the speed

    this.x += this.speedX;

    this.y += this.speedY;

​

    //   bounce the circles off the edges of the canvas

    if (this.x + this.size / 2 >= width || this.x - this.size / 2 <= 0) {

      this.speedX = -this.speedX;

    }

    if (this.y + this.size / 2 >= height || this.y - this.size / 2 <= 0) {

      this.speedY = -this.speedY;

    }

  }

  //  spin the circles from the center

  spinAround() {

    //     calculate center

    let centerX = width / 2;

    let centerY = height / 2;

    this.angle += 0.05;

    this.x =

      centerX +

      (this.x - centerX) * cos(this.angle) -

      (this.y - centerY) * sin(this.angle);

    this.y =

      centerY +

      (this.x - centerX) * sin(this.angle) +

      (this.y - centerY) * cos(this.angle);

  }

}

​

function setup() {

  createCanvas(400, 400);

  noStroke();

}

​

function draw() {

  background(0);

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

    circles[i].display();

    if (spin) {

      circles[i].spinAround();

    }

    if (keyIsPressed && key === " ") {

      circles[i].move();

    }

  }

  let size = random(10, 100);

  let x = random(width);

  let y = random(height);

  //   keep adding new circles but if array holds more than 100 circles start deleting

  let circle = new Circle(x, y, size);

  circles.push(circle);

  if (circles.length > 100) {

    circles.splice(0, 1);

  }

}

// if mouse is pressed, spin the circles

function mousePressed() {

  spin = !spin;

  if (spin) {

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

      circles[i].x = (width / circles.length) * i;

      circles[i].y = height / 2;

    }

  }

}

​