OpenGL antialiasing problem

Xumepoc

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);

if(refreshAll)
{
        QPixmap tmpP(width(), height());
        tmpP.fill(QColor(90,90,90));
        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;
}
painter.drawPixmap(0,0,BackGroundMapP);

//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.

SGaist

Hi,

What version of Qt ? On what OS ?

Xumepoc

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

Devopia53

@Xumepoc

Hi.

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

Xumepoc

Well I set the attribute for the app

a.setAttribute(Qt::AA_UseDesktopOpenGL);

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

Devopia53

@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.

Xumepoc

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