protected function setPositionProperty(array &$properties, $positionX, $positionY, $positionZ = null)
    {
        $position = array((float)$positionX, (float)$positionY);
        if ($positionZ) {
            array_push($position, (float)$positionZ);
        }
        $this->setProperty($properties, "pos", implode(" ", $position));
        return $this;
    }