​

  constructor(ix, iy, ivx, ivy, ir) {

    super(int(ix), int(iy), ivx, ivy, ir);

    this.ballColor = color(255, 255, 0);

​

    let baseHue = random(255);

    this.rotation = random(radians(360));

    let baseVel = this.vel.mag();

    this.angularV = (random(baseVel / 2, baseVel)) / 50.0;

​

    // Create a graphics object 'sprite' for drawing the balls.

    this.sprite = createGraphics(int(this.radius * 2 + 10), int(this.radius * 2 + 10));

    this.sprite.colorMode(HSB);

    this.sprite.noStroke();

    this.sprite.translate(this.sprite.width / 2, this.sprite.height / 2);

    for (let i = 0; i < 3; i++) {

      this.sprite.rotate(radians(120));

      this.sprite.fill((baseHue + (i * (255 / 3.0))) % 255, 200, 255); 

      this.sprite.arc(0, 0, this.radius * 2, this.radius * 2, 0, radians(120));

    }

    this.sprite.fill(255);

    this.sprite.ellipse(0, 0, this.radius * 0.8, this.radius * 0.8);

  }

​

  update() {

    let vMag = this.vel.mag();

    // Update the spin on the ball depending on how fast

    // it is travelling.

    if(vMag > 0.1){

      if(vMag > 1.0){

        this.rotation += this.angularV;    

      }

      else {

        this.rotation += this.angularV * vMag;      

      }

    }

    super.update();

  }

​

  display() {

    push();

    translate(this.loc.x, this.loc.y);

    rotate(this.rotation);

    image(this.sprite, -this.sprite.width / 2, -this.sprite.height / 2);

    pop();

  }

​

  limit() {

    super.limit();

    if (this.loc.y > height - 20 - this.radius) {

      this.loc.y = height - 20 - this.radius;

      this.vel.y = -this.vel.y;

    }

  }

}