# VTK Examples - Graph Testing
**URL:** https://discourse.vtk.org/t/vtk-examples-graph-testing/5561
**Category:** Development
**Created:** [April 17, 2021, 1:50am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561 "2021-04-17T01:50:01Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [April 17, 2021, 1:50am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/1 "2021-04-17T01:50:01Z")
I have come across an interesting discrepancy in testing [vtk-examples](https://gitlab.kitware.com/vtk/vtk-examples). The following five tests all pass in Windows but fail in Linux:
- [ConstructGraph](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/ConstructGraph)
- [EdgeWeights](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/EdgeWeights)
- [RandomGraphSource](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/RandomGraphSource)
- [ScaleVertices](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/ScaleVertices)
- [SideBySideGraphs](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/SideBySideGraphs)
These five examples in Linux mirror the graph image around a central vertical axis when compared to the Windows image. All the examples above show the windows image, for Linux I am getting an image like this:
for `ConstructGraph`, compare this with the Windows image here: [ConstructGraph](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/ConstructGraph).
Alternatively this shows the mirroring around the central vertical line of the image more clearly:
for `ScaleVertices`, compare this with the Windows image here: [ScaleVertices](https://kitware.github.io/vtk-examples/site/Cxx/Graphs/ScaleVertices).
The tests were run using Windows 10 Visual Studio 2019 16.4 and Kubuntu gcc (Ubuntu 10.2.0-13ubuntu1) 10.2.0 using the latest VTK Master.
Has anyone any ideas why these examples show this reflection in Linux when compared to Windows? If someone has time and a Mac I would be interested to know if the Mac image matches either Windows or Linux.
At this stage around 1000 of the C++ VTK Examples examples are tested with just two failures in Windows and these five failures in Linux (with an additional one: [XGMLReader](https://kitware.github.io/vtk-examples/site/Cxx/InfoVis/XGMLReader/)).
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### Author:  [@toddy](https://discourse.vtk.org/u/toddy)
#### Post date: [April 17, 2021, 5:33am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/2 "2021-04-17T05:33:56Z")
Perhaps it is not mirroring but showing the image from behind. i.e. flipping the z axis. Maybe left handed vs right handed coordinate systems for Windows vs Linux or vice versa?
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### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [April 17, 2021, 7:11am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/3 "2021-04-17T07:11:16Z")
That’s a possibility. However the labelling is Ok. This is puzzling because the same classes are used elsewhere in the examples and results are identical in Windows and Linux.
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### Author:  [@toddy](https://discourse.vtk.org/u/toddy)
#### Post date: [April 17, 2021, 7:14am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/4 "2021-04-17T07:14:05Z")
Can you display the camera axes in each?
Examples for shapes with a YZ plane of symmetry would appear to be identical.
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### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [April 17, 2021, 7:30am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/5 "2021-04-17T07:30:03Z")
That’ s a good point. I’ll have a go at that tomorrow.
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### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [April 29, 2021, 6:50am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/6 "2021-04-29T06:50:31Z")
The problem seems to be that the default layout: `Simple 2D` seems to give different results in Linux and Windows. I updated these examples to use `Force Directed` and the results now are consistent across Linux and Windows.
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### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [May 15, 2021, 7:37pm UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/7 "2021-05-15T19:37:36Z")
Please file an issue that `Simple 2D` is platform-dependent.
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### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [May 16, 2021, 6:16am UTC](https://discourse.vtk.org/t/vtk-examples-graph-testing/5561/8 "2021-05-16T06:16:48Z")
Done, please see: [https://gitlab.kitware.com/vtk/vtk/-/issues/18212](https://gitlab.kitware.com/vtk/vtk/-/issues/18212)