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Unexpected results with expand() and make_inverse() for spherical and geographic CS #498

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vissarion opened this Issue Jul 2, 2018 · 0 comments

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vissarion commented Jul 2, 2018

The code below (as posted in boost.geometry mailing list) returns

((0, 0), (5, 5))
((0, 0), (5, 5))
((-180, 0), (180, 5))
((-3.14159, 0), (3.14159, 5))

which is unexpected. There is an issue in the initialization of the box using make_inverse. Note that if the box is initialized by the first point point_type{0,0} of the expansion the result is as expected.

#include <boost/geometry.hpp>
#include <boost/geometry/algorithms/expand.hpp>
#include <boost/geometry/core/cs.hpp>
#include <boost/geometry/geometries/box.hpp>
#include <boost/geometry/geometries/point_xy.hpp>

#include <iostream>

// XXX -- default template parameters correspond to the Boost.Geometry
//        example; see
// https://www.boost.org/doc/libs/1_67_0/libs/geometry/doc/html/geometry/reference/algorithms/expand/expand_2.html
//
template < typename Coordinate = short int
           , typename CS = boost::geometry::cs::cartesian
           >
struct expand_example
{
  static void apply ()
  {
    using point_type = boost::geometry::model::d2::point_xy<Coordinate,CS>;
    using box_type = boost::geometry::model::box<point_type>;

    using boost::geometry::expand;

    box_type box = boost::geometry::make_inverse<box_type>();

    expand(box, point_type{0,0});
    expand(box, point_type{1,2});
    expand(box, point_type{5,4});
    expand(box, boost::geometry::make<box_type>(3,3,5,5));

    std::cout << boost::geometry::dsv(box) << std::endl;
  }
};

int main ()
{
  using namespace boost::geometry;
  expand_example<>::apply();
  expand_example<double,cs::cartesian>::apply();
  expand_example<double,cs::geographic<degree>>::apply();
  expand_example<double,cs::geographic<radian>>::apply();
}```

@vissarion vissarion added the bug label Jul 2, 2018

@vissarion vissarion closed this Jul 10, 2018

@awulkiew awulkiew added this to the 1.68 milestone Jul 10, 2018

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