constructor(x, y) {

    this.x = x;

    this.y = y;

    this.t = 0;

    this.speed = 0;

    this.start = 0;

    this.end = 100;

    this.start2 = 0;

    this.end2 = size;

  }

  display() {

    let x = (this.t - this.start) / (this.end - this.start);

    this.speed = this.start2 + easeInOutQuad(x) * (this.end2 - this.start2);

    push();

    translate(this.x, this.y);

    fill(255);

    rect(0, 0, size, size);

​

    fill(0);

    ellipse(this.speed - size/2, this.speed - size/2, size/2, size/2);

    // ellipse(this.speed, this.speed, size/2, size/2);

    ellipse(this.speed + size/2, this.speed + size/2, size/2, size/2);

    // ellipse(this.speed + size, this.speed + size, size/2, size/2);

    ellipse(this.speed + 3/2*size, this.speed + 3/2*size, size/2, size/2);

    pop();

​

    if (this.t >= size) {

      this.t = 0;

    } else {

      this.t += 1;

    }

  }

}