[vtkusers] offscreen rendering from gui application in vtk8/opengl2

[Andreas Buykx]

We recently switched our FEA application from vtk7.1 and the OpenGL backend to using 8.1 and the new OpenGL2 backend.

With 7.1 we could make off-screen images from the gui application using a temporary off-screen render window, temporarily moving renderers from the GUI render window to the off-screen render window, render the image and then move all renderers back to the GUI render window.
With vtk8.1 and OpenGL2 this causes OpenGL errors.

I reproduced this with the attached script which on vtk8.1.1 and the current head leads to an openGL error:

ERROR: In path-to/VTK-master/Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx, line 1814
vtkOpenGLPolyDataMapper (0x273dc00): failed after UpdateShader 1 OpenGL errors detected
  0 : (1282) Invalid operation

When the script is run with a global off-screen render window things work out fine.

Is my approach wrong (temporary render window, moving renderers to it temporarily) or is this a bug?

Thanks for your help!

DIANA FEA BV
Software Developers and Analysis Consultants for Civil and Geotechnical Engineering

Delftechpark 19a, 2628XJ, Delft, The Netherlands
Tel: +31 88 34262 15 (Direct) │ Tel: +31 88 34262 00 (Switchboard) │ Fax: +31 88 34262 99
http://dianafea.com<http://dianafea.com/>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://public.kitware.com/pipermail/vtkusers/attachments/20180709/cb80a9fa/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: writetopng.py
Type: application/octet-stream
Size: 1872 bytes
Desc: writetopng.py
URL: <https://public.kitware.com/pipermail/vtkusers/attachments/20180709/cb80a9fa/attachment.obj>