Geometry Boost List: [geometry] intersects (one geometry) possible issue

Subject: [geometry] intersects (one geometry) possible issue
From: joan (joan.abadie_at_[hidden])
Date: 2013-11-06 09:58:46

Hello,

I have a geometry that self intersects when using intersects (one geometry)
by should not.

<http://boost-geometry.203548.n3.nabble.com/file/n4025738/selfintersectissue_boost.png> 

This is the polygon that produce the self intersection :
 
        polygon myBoostPolygon;
        boost::geometry::read_wkt("POLYGON((137.14632454923444
200.61927877947369,50 224, 323 497,255 169,137.14632454923444
200.61927877947369))", myBoostPolygon);

        //check if boundary segments doesn't intersect with the polygon
        if (boost::geometry::intersects(myBoostPolygon))
        {
                cout << "Self intersects !" << endl;
        }

Regards 

Joan Abadie

Here is the full code to reproduce :

#include <deque>
#include <iostream>
#include <fstream>

#pragma warning(push)
#pragma warning(disable:4100)
#pragma warning(disable:4267)
#pragma warning(disable:4244)

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/linestring.hpp>
#include <boost/geometry/multi/geometries/multi_polygon.hpp>
#include <boost/geometry/multi/geometries/multi_linestring.hpp>
#include <boost/geometry/multi/geometries/multi_point.hpp>

#include <boost/geometry/io/wkt/wkt.hpp>
#include <boost/foreach.hpp>

#pragma warning(pop)

#include <boost/geometry/io/svg/svg_mapper.hpp>

typedef double coordinate_type;

typedef boost::geometry::model::d2::point_xy<coordinate_type,
boost::geometry::cs::cartesian> point_type; 
typedef boost::geometry::model::polygon<point_type> polygon;///	
typedef boost::geometry::model::linestring<point_type> linestring;
typedef boost::geometry::model::multi_point<point_type> multipoint;

using namespace std;

template <typename Geometry1, typename Geometry2>
void create_svg(std::string const& filename, Geometry1 const& a, Geometry2
const& b)
{
        typedef typename boost::geometry::point_type<Geometry1>::type point_type;
        std::ofstream svg(filename.c_str());

        boost::geometry::svg_mapper<point_type> mapper(svg, 400, 400);
        mapper.add(a);
        mapper.add(b);

        mapper.map(a,
"fill-opacity:0.1;fill:rgb(153,204,0);stroke:rgb(153,204,0);stroke-width:1");
        mapper.map(b,
"fill-opacity:0.5;fill:rgb(51,51,153);stroke:rgb(51,51,153);stroke-width:1");
}

int main()
{
        // Declare/fill input
        polygon myBoostPolygon;
        boost::geometry::read_wkt("POLYGON((137.14632454923444
200.61927877947369,50 224, 323 497,255 169,137.14632454923444
200.61927877947369))", myBoostPolygon);

        //check if boundary segments doesn't intersect with the polygon
        if (boost::geometry::intersects(myBoostPolygon))
        {
                cout << "Self intersects !" << endl;
        }

        //export result to svg
        multipoint mp;
        for (auto ite = myBoostPolygon.outer().begin(); ite !=
myBoostPolygon.outer().end(); ite++)
                boost::geometry::append(mp, *ite);
        create_svg("output.svg", myBoostPolygon, mp);

        return 0;
}

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