This example script linked below generates a surface with a vtk-shaped hole using vtkDelaunay2D. I think I understand the all of the script except for line 94: polys.InsertNextCell(28)
The script generates outer points and inner points, and a vtkCellArray. The cell array adds the first inner point (line 81) and then all outer points counter-clockwise (lines 92-93). Then the array adds point 28 (line 94), then all inner points clockwise (line 95-122)
If I comment out line 94, the hole collapses.
My question: Why is line 94 necessary?
https://gitlab.kitware.com/vtk/vtk/-/blob/v9.3.0/Filters/Core/Testing/Python/constrainedDelaunay.py
[edit] - It was a misreading on my part. It is not inserting cell point 28, it is inserting the next cell which will contain 28 points