CGAL users discussion list

[Obergude <>]

Hi guys,

i am really new to CGAL and i have some problems with it. So here it is:
I am trying to get the maximal outer boundary of a 3d-house-model and using:

        vector<Polygon_2> polygonList;
        Polygon_set_2 S;

        for(int i = 0; i<polygonCounter; i++){
                S.join (polygonListe[i]);
        }

to generate the outer boundary.

For the outer boundary of the house, i don't need to store the z-coordinate
of the polygon-vertices - only need to get a 2d-stamp of the house.
So i just create some "Polygon_2 p (Point_2(x,y))" and store the
x-y-coordinate. The problem is that i get some degenerated polygons because
of some vertical polygons in my 3d-model - like the walls of the house. The
vertices are like: Point_2(0,0), Point_2(1,0), Point_2(1,0), Point_2(0,0).
The problem is, that i get this error when a start the application:
       
        CGAL error: precondition violation!
        Expression: ! is_degen
        File: \cgal-3.5.1\include\cgal\arr_segment_traits_2.h
        Line: 125

because of the degenerate polygons.

So how can i test, if a polygon is degenerated? Or superiorly - how can i
get the outer boundary with a degeneratet polygon (like a wall (without
size) that is not under a roof).

I am really sorry about my bad english and i hope you get what i mean.
Thank you for help.

Cheers Obergude 
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