support for vtkPolyhedron?

[hugoledoux]

I would like to export my data to a VTK Unstructured Grid where each cell is a vtkPolyhedron.

This doesn't seem possible with your library, is it? I see in the examples that to store a icosahedron you decomposed it into tetrahedra, but I would like to have one cell in the mesh, not 20...

[phmkopp]

I just saw that you mentioned a polyhedron not a polygon, sorry for overreading that.

There is quite a lot of vtk functionality that is not documented in the official standard. In the sources

https://vtk.org/doc/nightly/html/vtkCellType_8h.html#ab1d6fd1f3177b8a2a32bb018807151f8a4e629d0fd13254bd0bc44e377ac3d8ee

you find

VTK_POLYHEDRON = 42

Let me try to create an example of that.

[phmkopp]

Oh I see what you mean. I deleted the first two messages because they weren't relevant.

You are right that we don't support giving faces at the moment and these seem to be required, right?

I found this file that works for me.

Being able to pass faces would require quite some restructuring, I have to think about this. I don't think there is a quick and easy way of doing this unfortunately. You could always hack it in if you need it and don't want to use VTK.

[phmkopp]

Let me know if you want to implement it in your local version, I think it should be quite easy.

[hugoledoux]

Thanks for your prompt reply and efforts!

I think I'll use VTK directly, there's a clear example where surfaces are defined:
https://examples.vtk.org/site/Cxx/GeometricObjects/Polyhedron/

If you eventually implement it then I'd be happy to use your header-only library!

[phmkopp]

Alright, no worries :)

We had similar requests about rather niche features before and I think we will eventually try to create something generic.

Good luck!