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  1. Qt Creator

QT OpenGL GL_POINTS Does not Draw Points on Linux IMX6



    • Type: Task
    • Status: Closed
    • Priority: P2: Important
    • Resolution: Invalid
    • Affects Version/s: Qt Creator 4.1.0
    • Fix Version/s: None
    • Component/s: C/C++/Obj-C++ Support
    • Labels:
    • Environment:

      QT 5.7 Running on Linux based IMX-6

    • Technical Risk:


      I created a subclass of QQuickItem, passing a vector of points in screen coordinates from a background thread to a slot in my subclass. Then, in the updatePaintNode method, I paint the background rectangle and create a node for the points, attaching the node to the main rectangle node. I then cycle through the points setting the vertices x and y value and mark the point node dirty. The size of the QQuickItem is 700 by 700 pixels and the point values in the vector are between 1 and 700 for both the x and y values.

      When I run my example code on an Linux X86 environment, the code works really well. I see the points being rendered on the component with excellent performance. I then recompile the same code for ARM IMX-6 and run it. No points are drawn, just the background rectangle. Both Linux 86 and ARM IMX-6 work when I draw lines in another component, however I need points only in this component, and points are not rendered in the ARM IMX-6 environment.

      I need a high performance rendering, such as what OpenGL can provide, as opposed to a QPainter style, since I am rendering 50000 to 100000 points up to 15 to 20 times per second.

      Does this mean that the OpenGL implementation on my ARM IMX-6 processor does not support point drawing and I have to make little triangles for each point?

      I don't see an example that uses GL_POINTS other than one or two online.

      I will attach the header file and cpp file for the QQuickItem subclass.

      Your feedback is much appreciated.


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            kosjar Nikolai Kosjar
            briangyetko Brian Gyetko
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