Qt 3D Billboarding

[guy incognito]

I'm trying to implement billboarding for a QPlaneMesh in Qt 5.8 C++. So far, the plane more or less faces towards the camera when I move around, but often it's upside down. I tried different rotations with QQuaternions with no success.

// camera
Qt3DRender::QCamera* camera = view->camera();
camera ->lens()->setPerspectiveProjection(90.0f, 16.0f/9.0f, 0.1f, 1000.0f);
camera ->setPosition(QVector3D(2.0f, 2.0f, 2.0f));
camera ->setUpVector(QVector3D(0, 1, 0));
camera ->setViewCenter(QVector3D(0, 0, 0));

// controls
Qt3DExtras::QFirstPersonCameraController* camController = new Qt3DExtras::QFirstPersonCameraController(rootEntity);
camController->setCamera(camera);

// signal/slots
QObject::connect(camera, &Qt3DRender::QCamera::positionChanged, plane, &Plane::rotate);

// Plane::rotate
void Plane::rotate(QVector3D target)
{
    planeTransform->setRotation(QQuaternion::rotationTo(planeTransform->translation(), target));
}

So the plane gets rotated towars the position of the camera.
Anyone got an idea how to improve things?