Unable to Obtain Surface Plot

[Radhika Prasad]

I have tried using the pyqtgraph surface plot example for obtaining a surface plot. Unfortunately, nothing appears. Please help.

Even in the example code, if I comment out everything else except for the saddle surface plot, then also nothing appears.

Here is the code:

from pyqtgraph.Qt import QtCore, QtGui

import pyqtgraph as pg

import pyqtgraph.opengl as gl

import numpy as np

## Create a GL View widget to display data

app = QtGui.QApplication([])

w = gl.GLViewWidget()

w.show()

w.setWindowTitle('pyqtgraph example: GLSurfacePlot')

#w.setCameraPosition(distance=50)

g = gl.GLGridItem()

g.scale(2,2,1)

g.setDepthValue(10)  # draw grid after surfaces since they may be translucent

w.addItem(g)

x = np.linspace(-8, 8, 50)

y = np.linspace(-8, 8, 50)

#z = np.exp((-x.reshape(50,1) ** 2) - (y.reshape(1,50) ** 2))

z = x.reshape(50,1)+y.reshape(1,50)

p = gl.GLSurfacePlotItem(x=x, y=y, z=z, shader='normalColor')

#p2.translate(-10,-10,0)

w.addItem(p)

[vas...@gmail.com]

Add to end of your code:

while w.isVisible():
    app.processEvents()

That's all,

Vasilije

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[Radhika Prasad]

Thanks. It works.

Just curious: This command is not mentioned in the documentation so how does one learn more about it?

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[Carlos Pascual]

processEvents is a QCoreApplication method documented here:

https://doc.qt.io/qt-5/qcoreapplication.html#processEvents

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[vas...@gmail.com]

Other way to make your app working is to add:

## Start Qt event loop unless running in interactive mode or using pyside.
if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

to the end of your code.

That's way is mentioned in most of the examples http://www.pyqtgraph.org/downloads/0.10.0/pyqtgraph-0.10.0-deb/pyqtgraph-0.10.0/examples/, but I think that is easier for start to have your own while loop instead to use update() function as in some examples.

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