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QCharts look different when using setUseOpenGL(true)

  • I'm trying to generate plots using a QChart with a QLineSeries. When I don't have OpenGL enabled, the plot is smooth and shows every detail. When I set it to true, looks very decimated. And the few points that do exist have the following pattern: there is a vertical line and then a diagonal line from that to another vertical line. Here is with no OpenGL.0_1473707761884_NoOpenGL.png

    Here is with OpenGL.


    All the rest of the code is identical. I just call setUseOpenGL(true) for the second. I'm running this on an Ubuntu 16.04.1 Virtual machine in VMWare Player.

    Thank you for any help and support.

  • Lifetime Qt Champion

    Upload images is currently broken so even you see them, others cannot.
    Its better to use external site and link here.
    Sorry for the inconvenience.

  • OK. Here are some Imgur links.

    Without OpenGL: alt text

    With OpenGL: alt text

  • I ran into exactly this same problem. It's caused by the GLWidget class using floating point precision, y values are fine, but your x values are greater than max float. What you could do is rebase your timestamps by subtracting the min timestamp from your series.

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