public function __construct(Vector $pos, Vector $lookAt)
{
$this->pos = $pos;
$down = new Vector(0.0, -1.0, 0.0);
$this->forward = Vector::norm(Vector::minus($lookAt, $this->pos));
$this->right = Vector::times(1.5, Vector::norm(Vector::cross($this->forward, $down)));
$this->up = Vector::times(1.5, Vector::norm(Vector::cross($this->forward, $this->right)));
}
public static function cross($a, $b)
{
$c = new Vector();
return $c->cross($a, $b);
}
