Vedo: Cannot show Volume on Plotter in qtwindow

[pasha009]

I am following the code given in the examples but i could not get the volume view in qtwindow. I get a blank screen when i try to show Volume derived from ndarray but works fine on predefined shapes.

import sys
from PyQt5 import Qt
import numpy as np
from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor
from vtkplotter import Plotter, Volume, Cube, Sphere

class MainWindow(Qt.QMainWindow):
    def __init__(self, parent=None):

        Qt.QMainWindow.__init__(self, parent)
        self.frame = Qt.QFrame()
        self.vl = Qt.QVBoxLayout()
        self.vtkWidget = QVTKRenderWindowInteractor(self.frame)
        self.vl.addWidget(self.vtkWidget)

        vp = Plotter(qtWidget=self.vtkWidget, bg='black')

        c = Cube(side=30)
        s = Sphere(r=15)
        X, Y, Z = np.mgrid[:30, :30, :30]
        scalar_field = ((X-15)**2 + (Y-15)**2 + (Z-15)**2)/225
        vol = Volume(scalar_field)
        vol.alpha([0, 0, 0.4, 0.9, 0.9])

        # vp.show(c)
        # vp.show(s)
        vp.show(vol)

        self.frame.setLayout(self.vl)
        self.setCentralWidget(self.frame)

        self.show()    # <--- show the Qt Window

    def onClose(self):
        print("Disable the interactor before closing to prevent it from trying to act on a already deleted items")
        self.vtkWidget.close()


if __name__ == "__main__":
    app = Qt.QApplication(sys.argv)
    window = MainWindow()
    app.aboutToQuit.connect(window.onClose) # <-- connect the onClose event
    app.exec_()

The same Volume can be rendered without Plotter

import numpy as np
from vtkplotter import Volume

def main():
    X, Y, Z = np.mgrid[:30, :30, :30]
    scalar_field = ((X-15)**2 + (Y-15)**2 + (Z-15)**2)/225
    vol = Volume(scalar_field)
    vol.alpha([0, 0, 0.4, 0.9, 0.9])
    vol.show(bg="black")

if __name__ == '__main__':
    main()

[marcomusy]

Uhmm that is strange because your first script works perfectly for me:

what python/vtk/vtkplotter version are you using?

[pasha009]

vtkplotter 2019.4.11 | vtk 8.1.2 | python 3.6
and pyqt version = 5.13.1

[marcomusy]

Same vtk and vtkplotter here, so I guess it's due to pyqt..
I've got python 3.7 from the latest anaconda which apparently comes with PYQT_VERSION_STR 5.9.2

What if you try:

        # vp.show(c)
        # vp.show(s)
        vp.show(vol, interactive=0)
        vp.interactor.Render()
        vp.interactor.Start()

[pasha009]

No, still a blank view. I also downgraded to pyqt 5.9.2 and python 3.7 but couldn't get the view.

[marcomusy]

Can you run the following:
(adapetd from here)

import sys
import vtk
from PyQt5 import Qt
from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor

from vtkplotter import load, datadir
vol = load(datadir+'embryo.tif')

class MainWindow(Qt.QMainWindow):

    def __init__(self, parent=None):
        Qt.QMainWindow.__init__(self, parent)

        self.frame = Qt.QFrame()

        self.vl = Qt.QVBoxLayout()
        self.vtkWidget = QVTKRenderWindowInteractor(self.frame)
        self.vl.addWidget(self.vtkWidget)

        self.ren = vtk.vtkRenderer()
        self.vtkWidget.GetRenderWindow().AddRenderer(self.ren)
        self.iren = self.vtkWidget.GetRenderWindow().GetInteractor()

        # Create source
        source = vtk.vtkSphereSource()
        source.SetCenter(0, 0, 0)
        source.SetRadius(1000.0)

        # Create a mapper
        mapper = vtk.vtkPolyDataMapper()
        mapper.SetInputConnection(source.GetOutputPort())

        # Create an actor
        actor = vtk.vtkActor()
        actor.SetMapper(mapper)

        self.ren.AddActor(actor)
        self.ren.AddVolume(vol)

        self.ren.ResetCamera()

        self.frame.setLayout(self.vl)
        self.setCentralWidget(self.frame)

        self.show()
        self.iren.Initialize()


if __name__ == "__main__":

    app = Qt.QApplication(sys.argv)

    window = MainWindow()

    sys.exit(app.exec_())

[pasha009]

Weird i cannot see the embryo when i run the above code. The ball comes fine.

[pasha009]

This workaround is functioning for me. But no idea why.
Just added

import vtk.qt
vtk.qt.QVTKRWIBase = "QGLWidget"

before any vtk imports

[marcomusy]

Thanks @pasha009 ! I will add a comment in the example.