[vtkusers] contour(s) of a vtkPolyData : points ordered and counter-clockwise

[Pascal Guehl]

Hello,

I work with C++, and VTK 5. I don't use the VTK graphics pipeline. I 
work with a custom real-time 3D engine and VTK is used to process 
scientific data.

I have to find the intersection between a mesh of radioactivity 
(vtkPolyData), and a contour of a city (vtkPoints), to see the impact on 
the city. To do this, I use a vtkClipPolyData with the vtkPolyData as 
input and a clip function vtkImplicitSelectionLoop built from the 
vtkPoints. I retrieve the intersected vtkPolyData.

I would like to retrieve the contour of the resulting vtkPolyData. It 
might be separated in several parts, so I need all contours of all 
largest regions.

I've seen the source code of the filter vtkExtractEdges, 
vtkLinearExtrusionFilter and the VTK book. I 've seen part of code that 
could help me : iteration on cells, then iteration on each each edges, 
and then test if there are neighbors, if not, that is an edge of one 
contour.

First, I would like to know if there is already a filter that do this ? 
I only find a of filter for vtkStructuredGrid : the 
vtkStructuredGridOutlineFilter…

Then, my problem is that I have to give this contour to a custom 
triangulator that must receive each point ordered and counter-clockwise. 
So my points must be inserted ordered and counter-clockwise. Is there a 
mean to do this with VTK, or I need to do this by myself in my algorithm ?

Best Regards,
Pascal