[vtkusers] Re: How do I get triangles from the vtkPolyData that vtkDelaunay2D produces?

[Grant Edwards]

On 2007-09-04, Grant Edwards <grante at visi.com> wrote:
> On 2007-09-03, Sylvain Jaume <sylvain.jaume at kitware.com> wrote:
>> Hi Edwards,
>>
>> You can use:
>>
>> vtkIdType npts, *pts;
>>
>> o->GetPolys()->InitTraversal();
>>
>> while(o->GetPolys()->GetNextCell(npts,pts))
>>    {
>>    cout << "triangle [" << pts[0] << " " << pts[1] << " " << pts[2] << "]" << endl;
>>    }
>
> Thanks for the example.
>
> The Python binding of the vtk library doesn't support the
> GetNextCell() and GetCell() methods for the vtkCellArray object
> returned by o->GetPolys().  Is there any other way to get the
> triangle info out?


I ended up having to call GetData and parse the polygon indexes
out of the raw data:

  o = delny.GetOutput()
  vertexes = [o.GetPoint(i) for i in xrange(o.GetNumberOfPoints())]

  pdata = polys.GetPolys().GetData()

  values = [int(pdata.GetTuple1(i)) for i in xrange(pdata.GetNumberOfTuples())]

  triangles = []
  while values:
      n = values[0]       # number of points in the polygon
      triangles.append(values[1:n+1])
      del values[0:n+1]

IMO, it's pretty lame to have to do it this way, but it seems
to work.

-- 
Grant Edwards                   grante             Yow! I've read SEVEN
                                  at               MILLION books!!
                               visi.com