[vtkusers] Difference between cells and polygons

David Goldsmith David.L.Goldsmith at noaa.gov
Fri Jul 13 17:36:02 EDT 2007

OK, I have the vtkCellArray "'list' of only the polygonal cells" using 
GetPoly; now, how do I get a cell's id?  If it's using GetCell or 
GetNextCell how do I get those functions' respective arguments?  And 
where is the retrieved value (cell pointer?) put, given that in one case 
the return value is void and in the other it's an int which appears to 
only indicate whether or not the end of list has been encountered?  Or 
is it customary to just use the call as the argument to a method that 
requires a cell id?  Thanks.


David E DeMarle wrote:
> In vtk a polygon is just one type of cell. The vtkPolyData class can 
> hold VTK_VERTEX'es for example, as well as VTK_POLYGONS. See 
> http://www.vtk.org/doc/nightly/html/classvtkPolyData.html 
> <http://www.vtk.org/doc/nightly/html/classvtkPolyData.html> or the 
> books for more information. Use GetPoly's to get a list of only the 
> polygonal cells, then use getcellpoints and getcellneighbors on each 
> cell id from that list.
> cheers
> Dave DeMarle
> On 7/13/07, *David Goldsmith* <d_l_goldsmith at yahoo.com 
> <mailto:d_l_goldsmith at yahoo.com>> wrote:
>     Hi!  In plain English, what is (are) the difference(s) between
>     cells and polygons?  And if I'm trying to loop over the triangles
>     (are these cells or polygons?) created by vtkDelaunay2D from
>     numbered points to get the point numbers of each triangle's
>     vertices, as well as each triangle's neighboring triangle objects,
>     which vtkPolyData method do I use for each of these tasks?  Thanks!
>     DG
>     <http://www.python.org>
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