CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Several way to proceed:

*the lazy one:
put each building blocks in an independent Nef polyhedron and make the
union (join) of all of then. Then you can extract a Polyhedron from it.
see: 
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Nef_3/Chapter_main.html
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Nef_3_ref/Class_Nef_polyhedron_3.html#Function_void_convert_to_polyhedron6Polyhedron__P9_const;

*by hand:
if your blocks shares full edges--if two edges overlap they have the 
same end points--use Halfedge_DS and Arrangement otherwise to extract
edges common to two blocks. Then using Polyhedron_3 with the incremental
builder, it's simply combinatoric to build the topological consistent 
buildings.
see:
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Polyhedron/Chapter_main.html
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Polyhedron_ref/Class_Polyhedron_incremental_builder_3.html

Sebastien.

sahermurad wrote:
> Hi, 
> I am new to CGAl and i want to use B-Rep to extrude building blocks from
> building footprints.
> I have a .txt file that stores the footprints as follow:
> Start
> 5,10
> 15,10
> 15,20
> 5,20
> Height
> 12
> End
> Start
> 15,10
> 25,10
> 35,10
> 45,10
> 45,20
> 15,20
> Height
> 15
> End
> Start
> 45,20
> 55,20
> 55,30
> 45,30
> Height
> 12
> End
> .
> .
> .
>
> My goal is that I have to read the above text file storing building
> footprints,
>  and then store the points in such a way that it should be Topologically
> Consistent.
> Then I have to use that Topologically consistent dataset to extrude
> Buildings which should be topologically as well geometrically consistent.
>
>
>
> Thank you! 
>
> --
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> http://cgal-discuss.949826.n4.nabble.com/How-to-implement-topological-model-in-CGAL-tp4298982p4298982.html
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