private function updateBBox($type, $data)
    {
        $min = $type . 'min';
        $max = $type . 'max';

        if (! isset($this->boundingBox[$min]) || $this->boundingBox[$min] == 0.0 || ($this->boundingBox[$min] > $data[$min])) {
            $this->boundingBox[$min] = $data[$min];
        }
        if (! isset($this->boundingBox[$max]) || $this->boundingBox[$max] == 0.0 || ($this->boundingBox[$max] < $data[$max])) {
            $this->boundingBox[$max] = $data[$max];
        }
    }