[vtkusers] Depth peeling and Qt

[Ignacio Fernández Galván]

Hi all,

I'm trying to get depth peeling and Qt interface to work together with 
VTK 6.2.0 (Ubuntu 16.04) and python, and I'm not having much success.

Depth peeling with "plain" VTK works fine 
(http://vtk.1045678.n5.nabble.com/Enable-depth-peeling-after-initialization-td5746070.html), 
but then problems start

I can't try PyQt4 because "import vtk" crashes (see 
https://gitlab.kitware.com/vtk/vtk/issues/16009).

So I modified 
https://www.vtk.org/Wiki/VTK/Examples/Python/Widgets/EmbedPyQt to work 
with PyQt5. I also modified QVTKRenderWindowInteractor to use PyQt5 and 
configure the RenderWindow with:

self._RenderWindow.SetMultiSamples(0)
self._RenderWindow.SetAlphaBitPlanes(1)

but (a): the sphere looks weird, like some facets being inside out and 
not being rendered, and (b): depth peeling is not enabled with the 
translucent object that works without Qt.

If I use an external (non-Qt) render window, it works fine, but then the 
event loop conflicts with Qt and I get a working VTK window and a frozen 
Qt interface.

I would appreciate some help or a working example, or even the assertion 
that it will never work.

Thanks,
Ignacio