Qwt 6.3.0 with Qt 6.8.2 - Antialiasing problem with QwtPlotOpenGLCanvas

Antialiasing does not seem to work in Qwt version 6.3.0 with the QwtPlotOpenGLCanvas class. This can also be observed in the Qwt example refreshtest. Antialiasing was still working with Qwt 6.2.0 and Qt 6.7.1. Does anyone have an idea how to improve the quality of the curves?

What happens when doing the following:

Code:

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auto canvas =  new QwtPlotOpenGLCanvas();
 
auto fmt = canvas->format();
fmt.setSamples( 16 );
 
canvas->setFormat( fmt );
...

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Thank you very much for your quick response.
Bye

Be aware that multisampling increases the GPU load and you might have an impact on the performance by choosing too many samples. So 16 might be too much.
Another question is of course why multisampling is enabled in your application with Qt 6.7 and not with Qt 6.8.

Uwe

Quote:

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Originally Posted by Uwe

Another question is of course why multisampling is enabled in your application with Qt 6.7 and not with Qt 6.8.

Uwe

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In the previous version of my application I work with Qwt 6.2.0 and Qt 6.5.3 (not Qt 6.7.1). Here QSurfaceFormat::samples() returns 4. So multisampling is enabled.
In the new verion of my application I use Qwt 6.3.0 and Qt 6.8.0. Here QSurfaceFormat::samples() returns -1. That means that multisampling is disabled and I have to use QSurfaceFormat::setSamples.

I now tried to use setSamples(8) in the previous version of my application, but I only see a black screen. Is this because of Qt or Qwt? Is there another solution.