[Boost-bugs] [Boost C++ Libraries] #13566: difference and intersection yield wrong result

Subject: [Boost-bugs] [Boost C++ Libraries] #13566: difference and intersection yield wrong result
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2018-05-16 06:51:43

#13566: difference and intersection yield wrong result
--------------------------------------+----------------------------
 Reporter:  Henrik Zimmer <henrik@…>  |      Owner:  Barend Gehrels
     Type:  Bugs                      |     Status:  new
Milestone:  To Be Determined          |  Component:  geometry
  Version:  Boost 1.66.0              |   Severity:  Showstopper
 Keywords:                            |
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 We are developing new algorithm that will hopefully be based on
 boost::geometry. Unfortunately we have come across some errors in the
 difference and intersection computations (possibly related to #13522 and
 #13553), which are a central part of the algorithm.

 I posted my original problem as a comment in #13522
 (https://wandbox.org/permlink/ThHHAW13DOdHbgEx)

 After reading #13553 I tried out the define BOOST_GEOMETRY_NO_ROBUSTNESS
 which at first seemed to work. However, I then ran into a problem at
 another position (https://wandbox.org/permlink/8YH8EiIRMtsUd1LH)
 The two polygons have finite, not too small intersection, but both the
 intersection and the difference are empty.

 The problem seems be that the two geometries overlap almost exactly in one
 vertex (0.0054, -0.02436) - this is the second vertex of the green polygon
 and the first vertex of the blue polygon.

 Changing the coordinate (0.0054) in the green polygon only slightly yields
 the correct result.

-- 
Ticket URL: <https://svn.boost.org/trac10/ticket/13566>
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