OpenGL antialiasing problem

  • Hi fellow programers.
    I have a problem with antialiasing in a QOpenGLWidget dirived widget. In the paintEvent I have

     QPainter painter(this);
     painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing);
            QPixmap tmpP(width(), height());
            QPainter painter_tmp(&tmpP);
            painter_tmp.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing);
          //Some drawing here
           BackGroundMapP = tmpP.copy(0,0,tmpP.width(), tmpP.height()); //BackGroundMapP is s Pixmap
            refreshAll= false;
    //Some more drawing here
    qDebug() << painter.renderHints(); // This is showing that the flags are set OK.

    But the result is without Antialiasing or Text Antialiasing for everything drawn by painter. If I test to see if the flags are set correctly I get that they are. All drawn with painter_tmp is Antialiased though!! So what could be the problem? Apparently there are no driver problems, as everything drawn with painter_tmp is working fine.

  • Lifetime Qt Champion


    What version of Qt ? On what OS ?

  • Hi,
    It is happening with Qt 5.4.1 on Windows 7 and on Qt 5.6.1 on Windows 10.

  • @Xumepoc


    Have you set the surface format for the widget or app.?

  • Well I set the attribute for the app


    Do I have to set the QSurfaceFormat for the widget too?

  • @Xumepoc

    Of course you need to set the surface format for the widget or app.
    A.setAttribute (Qt :: AA_UseDesktopOpenGL) has nothing to do with this problem.

  • Yep :D :D you were completely right. Set it to sample 10 and everything is crisp and smooth. Thank you very much.

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