Setting offset between two rotating QGraphicsRectItems

Question

I have a red rectangle (QGraphicsRectItem), which position and rotation depends on pressed keys (up, down, left, right, turn right, turn left). I want another - green rectangle to follow red's position and rotation, but with a certain offset, in this manner:

I'd like to know how to achieve it without making the red parent of the green. My code (withotu the desired offset) is:

Game::Game()
{
    player->setRect(0,0,100,100);
    player->setBrush(Qt::red);
    player->setPos(400,300);
    this->addItem(player);
    player->setFocus();
 
    rectItem->setRect(0,0,100,100);
    rectItem->setBrush(Qt::green);
    rectItem->setPos(400,330);
    this->addItem(rectItem);
 
    player->setZValue(10);
    rectItem->setZValue(1);
 
    player->setTransformOriginPoint(player->boundingRect().width()/2 ,
                                    player->boundingRect().height()/2 );
    rectItem->setTransformOriginPoint(player->transformOriginPoint());
}
 
 
void Game::advance()
{
    rectItem->setPos(player->pos().x(), player->pos().y());
    rectItem->setRotation(player->rotation());
}