CGAL users discussion list

[Michael Jeulin-L <>]

Hi,

Excuse me If the last question is stupid, but I don`t really know how I can
create Polygons directly from the alpha Shape.

My first Idea was to navigate into all the segment and aggregate all the
segment with one common point together. But This method seems to be awkward
with an awful computational time.

Another way, CGAL may do this stuff automatically :
http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Alpha_shapes_2_ref/Class_Alpha_shape_2.html#Cross_link_anchor_995

--> Implementation

"A.number of solid components performs a graph traversal and takes time linear
in the number of faces of the underlying triangulation."

So I don`t know how I could use this perform in order to make polygons :
[
typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Polygon_2<K> Polygone;
typedef vector<Polygone>     Polygones;
] 

directly from my alpha_shape structure...
Thank you very much.