id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
13096	boost::geometry::intersection results depend on polypoints inputorder	kle@…	Barend Gehrels	"Hello,

when calculating the intersection of the givin polygons, the result depends on the order of the inputpoints.


{{{

#include <boost/geometry/geometry.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/point_xy.hpp>

int main(int argc, char* argv[])
{
  typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double>> boost_polygon;

  boost_polygon RedPoly, GreenPoly, RedPolyReverted, GreenPolyReverted;
  boost::geometry::read_wkt(""POLYGON((864.11024748062812 524.94908797221251, 881.01048034069004 524.77831898197212, 877.68802698783907 501.82023487475703, 860.75736496460991 501.99865072086430, 864.11024748062812 524.94908797221251))"", RedPoly);
  boost::geometry::read_wkt(""POLYGON((864.62221751510151 524.94391475320754, 868.20628459909278 524.90769942280622, 864.93694798456659 502.47800172931238, 861.34657616182551 502.51580174027310, 864.62221751510151 524.94391475320754))"", GreenPoly);
  boost::geometry::read_wkt(""POLYGON((860.75736496460991 501.99865072086430, 877.68802698783907 501.82023487475703, 881.01048034069004 524.77831898197212, 864.11024748062812 524.94908797221251, 860.75736496460991 501.99865072086430))"", RedPolyReverted);
  boost::geometry::read_wkt(""POLYGON((861.34657616182551 502.51580174027310, 864.93694798456659 502.47800172931238, 868.20628459909278 524.90769942280622, 864.62221751510151 524.94391475320754, 861.34657616182551 502.51580174027310))"", GreenPolyReverted);

  boost::geometry::correct(RedPoly);
  boost::geometry::correct(GreenPoly);
  boost::geometry::correct(RedPolyReverted);   // reverts order of points and is now equal it RedPoly
  boost::geometry::correct(GreenPolyReverted); // reverts order of points and is now equal it GreenPoly

  std::list<boost_polygon> output;
  boost::geometry::intersection(RedPoly, GreenPoly, output);  // error: output is empty

  std::list<boost_polygon> outputReverted;
  boost::geometry::intersection(RedPolyReverted, GreenPolyReverted, outputReverted); // correct: outputReverted.front equals GreenPoly

  return 0;
}
}}}
"	Bugs	new	To Be Determined	geometry	Boost 1.64.0	Problem		intersection