[vtkusers] vtkExtractEdges changes point IDs?

[David Doria]

> Yes.  Here is what happens.  The "for" loops in the filter traverse
> the geometry, i.e. the cells.  Whenever an input point is needed for
> the output geometry, it is inserted into the output points.  As a
> result, the sorting of the output points is different from the input
> points.
>
> Conversely, for filters that traverse the points (as opposed to
> traversing the cells), the output points are usually kept in the same
> order as the input points.
>
>   David
>

Ah, makes sense. Thanks for the explanation.

David