<div dir="ltr"><div><div><div>Hello Kathleen,<br><br></div>Could you try with the 
latest VTK (master branch)? I encountered a bug that sounds very similar to what you are
 describing and a patch has been integrated in VTK recently:<br><a href="https://gitlab.kitware.com/vtk/vtk/commit/a7988f5c530d6db31d6d9a774049c5247a9ac80c">https://gitlab.kitware.com/vtk/vtk/commit/a7988f5c530d6db31d6d9a774049c5247a9ac80c</a><br><br></div>Hope this helps,<br><br></div>Francois<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Mar 30, 2018 at 4:18 PM, Kathleen S. Biagas <span dir="ltr"><<a href="mailto:biagas2@llnl.gov" target="_blank">biagas2@llnl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello,<br>
<br>
I used the Offscreen Renderer example from here:<br>
<a href="https://lorensen.github.io/VTKExamples/site/Cxx/Utilities/OffScreenRendering/" rel="noreferrer" target="_blank">https://lorensen.github.io/<wbr>VTKExamples/site/Cxx/<wbr>Utilities/OffScreenRendering/</a><br>
<br>
But I modified it for use with VTK-8 by removing the Factory logic that<br>
sets up Mesa classes.<br>
<br>
This works great.<br>
<br>
However, when I duplicate all the code (probably more than is strictly<br>
necessary) to create a second render window, then it segv's in a call to<br>
XQueryExtension during vtkXOpenGLRenderWindow::<wbr>PopContext.<br>
<br>
If I comment out the logic that turns on OffScreen Rendering, then it<br>
doesn't crash.<br>
<br>
I compiled VTK-8.1 with gcc 6.2, qt 5.10.1, python 2.7.14, and system<br>
GL.<br>
<br>
This *should* work, shouldn't it?<br>
<br>
I've attached the OffScreenRendering source code I used, as well as<br>
output from a call to 'ReportCapabilities' on the vtkRenderWindow.<br>
<span class="HOEnZb"><font color="#888888"><br>
Kathleen<br>
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