Передача по ссылке полигона

void PaintScene::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
pol.clear();
Curve *item = new Curve(QPen(ii.col,ii.val),pol, event->scenePos());
item->setPos(event->pos());
tempFigure = item;
this->addItem(tempFigure);
}

void PaintScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
    tempFigure->setEndPoint(event->scenePos());
    this->update(QRectF(0,0,this->width(), this->height()));
    if (m_typeFigure == CurveT)
    {
    pol.push_back(event->scenePos());
    }
}

{
class Curve : public Figure
..
public:
    explicit Curve(QPen pen, QPolygonF &pol, QPointF point);
    ~Curve();
}

{
     Curve::Curve(QPen pen, QPolygonF &pol, QPointF point, QObject *parent) :
    {
        Q_UNUSED(point)
        Figure::penn = pen;
        polyg = &pol;
     }
...
     void Curve::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    painter->setPen(penn);
    painter->drawPolyline(*polyg);
...
}

class Figure
...
public:
...
    QPolygonF *polyg;
...