[PyQt] QOpenGLWidget

[Thomas Caswell]

You should also look at pyqtgraph (http://www.pyqtgraph.org) which places a
premium on speed.

Depending on exactly how much data you have and exactly how fast you need
to go, using blitting it Matplotlib it may be possible to eek out a bit
more performance.

Tom

On Sun, Sep 22, 2019 at 8:03 PM V. Armando Sole <sole at esrf.fr> wrote:

> Hello,
>
> Perhaps you want to give a try at the silx library
> (http://www.silx.org/doc/silx/latest/). I provides high-level PyQt
> visualization widgets with a dual backend (matplotlib and PyOpenGL) so
> that one does not need to know any OpenGL to get the performance.
>
> Best regards,
>
> Armando
>
> On 22.09.2019 17:07, kristof.mulier at telenet.be wrote:
> > Hi,
> >
> > I'm building an application in PyQt5 for which I need to draw 2D live
> > graphs. I'm looking for a way to render them with the GPU.
> >
> > 1. FIRST APPROACH
> >
> > ---------------------
> >
> > My first approach was embedding matplotlib into PyQt5. Matplotlib is
> > not so fast, because _it relies on CPU-rendering only_.
> >
> > 2. SECOND APPROACH
> >
> > ------------------------
> >
> > I build my own PyQt5 widget and override the paintEvent() method to
> > draw a few thousand lines with the QPainter() to display the live
> > graph. The graph points are stored in numpy arrays. I simply draw
> > lines between the points. Unfortunately,  QPainter() relies on the
> > CPU.
> >
> > Right now, it looks like I have several options for GPU-based
> > rendering:
> >
> >  - QOPENGLWIDGET
> >  (see https://doc.qt.io/qt-5/qopenglwidget.html). From what I read on
> > the Qt docs, it looks too good to be true. I would simply need to
> > subclass QOpenGLWidget instead of QWidget. Apparently, I eveb don't
> > have to change anything in the paintEvent() method. Is this real?
> > Where are the pitfalls?
> >
> >  - PYOPENGL
> > Python bindings for OpenGL. I have no OpenGL experience. I found the
> > following tutorial: https://www.labri.fr/perso/nrougier/python-opengl/
> > . Great, but I'm afraid to spend a lot of time on this. When I scroll
> > through the tutorial, it appears to me that the focus is on 3D shapes.
> > I don't need that.
> >
> >  - QGRAPHICSVIEW
> >
> > I remember reading something about QGraphicsView() in a StackOverflow
> > answer. It would be a Qt class to draw lots of shapes. But can it
> > handle thousands of tiny lines that form the live graph? Does it rely
> > on the CPU or the GPU for rendering?
> >
> > Could you point me in the right direction please?
> > _______________________________________________
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-- 
Thomas Caswell
tcaswell at gmail.com
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