Graphics programming • Unexpected difference between Wayland and X11

Hi,

I maintain a version of the Cura slicer for the Raspberry Pi 4/5. The UI is based on PyQT and uses OpenGL shaders. Until now, the application has been built only for X11 displays and it looks OK when running under Wayland using Xwayland. Recently, I have built a version that uses the Wayland client support that Qt provides and so it runs without using Xwayland. It's mostly functioning OK apart from a crash that occurs when drag/dropping certain file types but it also has a weird visual difference compared to the X11 display.

Here is a picture of the display when the application runs under Xwayland and it renders into a QEGLPlatformContext ...
You can see some discrete banding but it's not too obvious.

And here is a similar view when the application runs using native Wayland and it renders into an QWaylandGLContext ...
Using Wayland, the shading is less smooth with discrete bands very visible.

Does anyone have any idea as to what's causing this?

Thanks,

Mark

Statistics: Posted by burtoogle — Tue Jan 23, 2024 8:58 am

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