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["Sebastien Loriot (GeometryFactory)" <>]

Same here, the outer boundary should be oriented counterclockwise

Sebastien.

CGALFan wrote:
> Hi!
>
> Im struggeling with this problem many days now and i couldn't find a
> solution: I coded an application to compute the offset polygons of a given
> polygon. It worked with my initial test polygon, but when i tried another
> one the program failed.
> I tested now the Show_offset_polygon.cpp from the examples and it also
> didn't work with my polygon and also not the sample_4.dat.
>
> The code is:
>
> #include<vector>
> #include<iterator>
> #include<iostream>
> #include<iomanip>
> #include<string>
> #include <fstream>
>
> #include&lt;boost/shared_ptr.hpp&gt;
>
> #include&lt;CGAL/Exact_predicates_inexact_constructions_kernel.h&gt;
> #include&lt;CGAL/Polygon_with_holes_2.h&gt;
> #include&lt;CGAL/create_offset_polygons_from_polygon_with_holes_2.h&gt;
>
> #include "dump_to_eps.h"
>
> typedef CGAL::Exact_predicates_inexact_constructions_kernel K ;
>
> typedef K::Point_2                    Point ;
> typedef CGAL::Polygon_2<K>            Polygon ;
> typedef CGAL::Polygon_with_holes_2<K> Polygon_with_holes ;
>
> typedef boost::shared_ptr<Polygon_with_holes> Polygon_with_holes_ptr ;
>
> typedef std::vector<Polygon_with_holes_ptr> Polygon_with_holes_ptr_vector ;
>
> int main( int argc, char* argv[] )
> {
>   Polygon_with_holes input ;
>   
>   if ( argc > 0 )
>   {
>     std::string name = "polygon.dat"; //argv[1] ;
>   
>     std::cout << "Input file: " << name << std::endl ;
>       
>     std::ifstream is(name.c_str()) ;
>     if ( is )
>     {
>       is >> input ;
>       
>       double lOffset = 0.25 ;
>       
>       if ( argc > 2 )
>         lOffset = std::atof(argv[2]);
>       
>       std::cout << "Offsetting at: " << lOffset << std::endl ;
>
>       Polygon_with_holes_ptr_vector offset_polygons =
> CGAL::create_interior_skeleton_and_offset_polygons_with_holes_2(lOffset,input);
>
>       std::string eps_name ;
>       if ( argc > 3  )
>            eps_name = argv[3];
>       else eps_name = name + ".offset.eps" ;
>       
>       std::ofstream eps(eps_name.c_str()) ;
>       if ( eps )  
>       {
>         std::cerr << "Result: " << eps_name << std::endl ;
>         dump_to_eps(input,offset_polygons,eps);
>       }
>       else
>       {
>         std::cerr << "Could not open result file: " << eps_name << std::endl
> ;
>       }  
>     }  
>     else
>     {
>       std::cerr << "Could not open input file: " << name << std::endl ;
>     }  
>   }
>   else
>   {
>     std::cerr << "Computes the interior offset of a polygon with holes and
> draws the result in an EPS file." << std::endl 
>               << std::endl 
>               << "Usage: show_offset_polygon <input_file> [offset_distance]
> [output_eps_file]" << std::endl
>               << std::endl 
>               << "       intput_file  Text file describing the input polygon
> with holes." << std::endl
>               << "         (See inputfile_format.txt for details)" <<
> std::endl
>               << "       offset_distance [default=0.25]." << std::endl 
>               << "       output_file     [default='innput_file.offset.eps']"
> << std::endl ; 
>   }
>
>   return 0;
> }
>
>
> My polygon.dat is:
>
> 6
> 714.279947091038 700.8634379411073
> 928.4204862107923 634.3685299163473
> 1036.226377703022 541.314748318798
> 1063.559817470496 471.3282081692817
> 756.8882581986625 329.5089199763363
> 658.0658590822038 508.0303788777358
> 0
>
>
> The error is:
>
> terminate called after throwing an instance of 'CGAL::Assertion_exception'
>   what():  CGAL ERROR: assertion violation!
> Expr: lParent
> File: /usr/local/include/CGAL/arrange_offset_polygons_2.h
>
> Please help me!
>
> Nice greets
> Gernot
>
> --
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