Iterate over Triangles in Tetrahedron Data (without redundancies)

[Flashtim]

Hey there!
I am currently working with a vtkUnstructuredGrid object that is made up of a collection of tetrahedron cells. I now want to iterate over all triangles.
One way to do so ist to use the GetCellData(); function, but this will lead to a list of tetrahedra, which I can then use to visit all faces. This leads to several triangles being visited twice, which is a significant overhead. Does VTK offer a better way that I just haven’t found yet?

There was a similar question, which was never really answered.

Iterate over the faces of an UnstructuredGrid

What’s the most efficient way to iterate over all the faces of an UnstructuredGrid? I know I can iterate over the cells first and then get its faces for each cell, but this will lead me to visit the same face two times (one per each cell that shares the face). Is there a way to just iterate over all the faces? Thanks.

Thanks for any responses,
-Flashtim

[will.schroeder]

I answered your question in the discourse thread…

[Flashtim]

Thanks for the suggestion, I thought of a similar way to approach this.
But you would also say, that there is no straightforward function that would provide, e.g., an array of all unique triangles?

[will.schroeder]

That’s a good suggestion, but I believe the current philosophy is that such a face structure would be too slow and too memory inefficient. However, for all I know there may be a filter (or filter combination) that can do what you want but nothing is coming to me at the moment. Are you willing to try writing some code and creating a MR? It could be added to vtkUnstructuredGridBase with an implementation in vtkUnstructuredGrid.

[Flashtim]

Yeah, I was thinking about doing that. Let’s see, it might result as a sideproduct of my current project.
Thanks for your suggestions.