VTK Examples - Graph Testing

I have come across an interesting discrepancy in testing vtk-examples. The following five tests all pass in Windows but fail in Linux:


for ConstructGraph, compare this with the Windows image here: 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.

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).

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?

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.

Can you display the camera axes in each?

Examples for shapes with a YZ plane of symmetry would appear to be identical.

That’ s a good point. I’ll have a go at that tomorrow.

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.

Please file an issue that Simple 2D is platform-dependent.

Done, please see: https://gitlab.kitware.com/vtk/vtk/-/issues/18212