[vtkusers] vtkContourFilter on 2D Cells (vtkPolygon)

[Randall Hand]

You're setting the value of all 4 points to "1", and then taking a contour
of 1.  It doesn't intersect anywhere, so I think it's working just right.

Change the scalars to:
  for (int i =0; i <4; i++) scalars->InsertNextValue(i);

And then you'll have 4 different values.

On 2/1/06, Frederic DANESI <fred.danesi at netcourrier.com> wrote:
>
> Dear vtkusers,
>
> I am trying something that I believe quite simple, but without any
> success.
>
> I would like to build some vtkPolygons (2D) and then to use
> vtkContourFilter
> to obtain an isoline (which I assume to match with the boundary of all
> polygons together) ...
>
> Even with only one polygon, vtkContourFilter does not do anything
> (vtkContourFilter (09981DD8): Created: 0 points, 0 verts, 0 lines, 0
> triangles) ...
>
> I enclosed my code hereafter.
>
> I will really appreciate any idea, tips on what I missed or what I'm doing
> wrong, or any code example...
>
> Thanks,
> Fred.
>
> ----
>
> vtkPolygon *polygon = vtkPolygon::New();
>
>   polygon->GetPointIds()->SetNumberOfIds(4);
>   polygon->GetPointIds()->SetId(0,0);
>   polygon->GetPointIds()->SetId(1,1);
>   polygon->GetPointIds()->SetId(2,2);
>   polygon->GetPointIds()->SetId(3,3);
>
>   polygon->GetPoints()->SetNumberOfPoints(4);
>   polygon->GetPoints()->SetPoint(0, 0.0, 0.0, 0.0);
>   polygon->GetPoints()->SetPoint(1, 10.0, 0.0, 0.0);
>   polygon->GetPoints()->SetPoint(2, 10.0, 10.0, 0.0);
>   polygon->GetPoints()->SetPoint(3, 0.0, 10.0, 0.0);
>
>   vtkIntArray * scalars = vtkIntArray::New();
>   scalars->Allocate(5000,10000);
>   for (int i =0; i <4; i++) scalars->InsertNextValue(1);
>
>   vtkPolyData * polygonPolyData = vtkPolyData::New();
>   polygonPolyData->Allocate(1,1);
>   polygonPolyData->InsertNextCell(polygon->GetCellType(),
> polygon->GetPointIds());
>   polygonPolyData->SetPoints(polygon->GetPoints());
>   polygonPolyData->GetPointData()->SetScalars(scalars);
>
>   // mapping and rendering "polygonPolyData" ==> OK ...
>
>   vtkContourFilter * flt = vtkContourFilter ::New();
>   flt->SetInput((vtkDataSet *)output);
>   flt->DebugOn();
>   flt->SetValue(0,1);
>
>   //+ mapping and rendering  ==> vtkContourFilter (09981DD8): Created: 0
> points, 0 verts, 0 lines, 0 triangles ... empty ...
>
> --
> Responsable Département DINCCS
> (Département Ingénierie Numérique Conception Collaborative et Simulation)
> Pole de Haute Technologie
> 08000 Charleville-Mézières
> Tél. 03.24.37.89.89
>
>
>
>
> _______________________________________________
> This is the private VTK discussion list.
> Please keep messages on-topic. Check the FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
> Follow this link to subscribe/unsubscribe:
> http://www.vtk.org/mailman/listinfo/vtkusers
>



--
Randall Hand
Visualization Scientist,
ERDC-MSRC Vicksburg, MS
Homepage: http://www.yeraze.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20060201/d5516f4d/attachment.htm>