HI!
 You can do it like this:
 vtkDataSet::GetNumberOfCells();
 for(cellId = 0,cellId<number,cellId++)
{
   vtkCell *cell = vtkDataSet::GetCell(cellID);
   if(cell->GetCellType() == VTK_TRIANGLE)
   nTriangle ++;
}
 It is slow possibly,but I can not find other method!
 
Regards,
				
        beelin
        beelin at sohu.com
          2006-07-11