Method plus

code/draw_layout.js:7–9

(other)

    this.x = x; this.y = y;
  }
  plus(other) {
    return new Vec(this.x + other.x, this.y + other.y);
  }
  minus(other) {
    return new Vec(this.x - other.x, this.y - other.y);
  }