QGraphicsItem disappeare during rotation around Qt::XAxis

[radek.z]

Hi,
I can't find the reason, why my object disappearing during transformation around the XAxis.
I am showing here the short code which better expain what I mean.
When I use QTransform on the scene and rotate the view, then if i use high angle the QGraphicsRectItem disappeare.
Or if I make the view window height bigger, which anybody who would help me can try in this small app.

#include <QApplication>
#include <QGraphicsView>
 
 
int main(int argc, char **argv)
{
    QApplication app(argc, argv);
 
    QGraphicsScene scene;
    scene.addRect(QRectF(0,0,100,100), QPen(), QBrush(QColor(Qt::red)));
    QGraphicsView view(&scene);
    view.show();
 
    QTransform transform;
    transform.rotate(80, Qt::XAxis);
    view.setTransform(transform);
 
    return app.exec();
}

#include <QApplication>
#include <QGraphicsView>


int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QGraphicsScene scene;
    scene.addRect(QRectF(0,0,100,100), QPen(), QBrush(QColor(Qt::red)));
    QGraphicsView view(&scene);
    view.show();

    QTransform transform;
    transform.rotate(80, Qt::XAxis);
    view.setTransform(transform);

    return app.exec();
}

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[wysota]

I can see the item just fine. Bear in mind that graphics items are flat, if you rotate them 90 deg. they will disappear because their z size is 0.

[radek.z]

Hi,
did you try to change window size? if I make it vertically bigger the item disappear and again appear when i make the window smaller.
If you tried it and you still can see it then the problem will be somewhere else, but I have no idea where. I was trying on the different comps with kubuntu and and also on windows. The problem was on all of them.

[angelhigh]

Hi, you should know what really you want to do. If you only want to rotate the rect, just use QGraphicsItem::rotate(). The transform will rotate the whole coordinate.

[radek.z]

Hi,
the code above is just simple example to demonstrate what I mean. I am doing chessboard, so there should be option to zoomin and out and to rotate it. But then is coming the problem which I described above.

Radek

[radek.z]

so looks like it was a bug, i have tried on qt 4.5 and the transformation is fine