constructor() {

    this.mid = floor((width/size)/2);

    this.x = this.mid;

    this.y = this.mid;

    this.s = 0;

    this.ds = 1;

  }

  display(grid) {

    for (let i=-this.s; i<this.s; i++) {

      for (let j=-this.s; j<this.s; j++) {

        if (grid[(this.x + i + cols) % cols][(this.y + j + rows) % rows] == 1) {

          fill(255);

        } else {

          fill(0);

        }

        rect((this.x + i)*size, (this.y + j)*size, size, size);

      }

    }

    if (this.s > this.mid || this.s < 0) {

      this.ds *= -1;

    } 

    this.s += this.ds;

  }

}