[Boost-bugs] [Boost C++ Libraries] #11121: Invalid result of difference() for integral coordinates.

Subject: [Boost-bugs] [Boost C++ Libraries] #11121: Invalid result of difference() for integral coordinates.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-03-18 15:04:24

#11121: Invalid result of difference() for integral coordinates.
-------------------------------------------------+-------------------------
 Reporter:  awulkiew                             |      Owner:
     Type:  Bugs                                 |  barendgehrels
Milestone:  To Be Determined                     |     Status:  new
  Version:  Boost Development Trunk              |  Component:  geometry
 Keywords:  difference, integral, setops,        |   Severity:  Problem
  get_turns                                      |
-------------------------------------------------+-------------------------
 For polygons:

 {{{
 green = "POLYGON((-8042 -1485,-8042 250,-8042 250,15943 254,15943
 -1485,-8042 -1485))",
 blue = "POLYGON((-7901 -1485,-7901 529,-7901 529, 15802 544, 15802 -1485,
 -7901 -1485))"
 }}}

 The result of difference(green, blue) and/or difference(blue, green) is
 invalid if the polygons use `int` coordinate type.

 I think it may be related to get_turns/cart_intersect and ratios/fractions
 but it needs further investigation. I noticed that turns has wrong
 coordinates, always endpoints of segments are picked as if internally
 ratios were always truncated to 0.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11121>
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