Why boost::geometry::intersection does not work correct?

Question

I wrote next test function for Boost Geometry intersection function

typedef boost::geometry::model::polygon<boost::tuple<int, int> > Polygon;

void test_boost_intersection() {
  Polygon green, blue;
  boost::geometry::read_wkt("POLYGON((0 0,0 9,9 9,9 0,0 0))", green);
  boost::geometry::read_wkt("POLYGON((2 2,2 9,9 9,9 2,2 2))", blue);
  std::deque<Polygon> output;
  boost::geometry::intersection(green, blue, output);
  BOOST_FOREACH(Polygon const& p, output)
  {
    std::cout << boost::geometry::dsv(p) << std::endl;
  }
};

I expected output result as:

(((2, 2), (2, 9), (9, 9), (9, 2), (2, 2)))

but I got:

((((1, 9), (9, 9), (9, 2), (2, 2), (1, 9))))

I use Boost 1.54.

If I'd change first polygon, intersection works correct.

EDIT: When I changed type of polygon to

boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> >

it started to work correct. So can't I use previous type for all times?

Please make your sample code selfcontained. People simply don't want to spend 10 minutes making your code compile if you could have included the missing 5 lines of code. — sehe, May 28 '14 at 12:40
@sehe, okay, thank you for that comment and answer, I'll do it next time when have a question. — aptypr, May 29 '14 at 03:15

sehe · Accepted Answer · 2014-05-28T12:47:24.680

You need to correct the input polygons to satisfy the algorithm preconditions: Live On Coliru prints

(((2, 9), (9, 9), (9, 2), (2, 2), (2, 9)))

#include <boost/tuple/tuple.hpp>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>
#include <boost/foreach.hpp>
typedef boost::geometry::model::polygon<boost::tuple<int, int> > Polygon;

BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)

void test_boost_intersection() {
    Polygon green, blue;
    boost::geometry::read_wkt("POLYGON((0 0,0 9,9 9,9 0,0 0))", green);
    boost::geometry::read_wkt("POLYGON((2 2,2 9,9 9,9 2,2 2))", blue);
    boost::geometry::correct(green);
    boost::geometry::correct(blue);
    std::deque<Polygon> output;
    boost::geometry::intersection(green, blue, output);
    BOOST_FOREACH(Polygon const& p, output)
    {
        std::cout << boost::geometry::dsv(p) << std::endl;
    }
}

int main()
{
    test_boost_intersection();
}

Why boost::geometry::intersection does not work correct?

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