[geos-devel] [GEOS] #588: valid polygon when cw, not valid when ccw

[GEOS]

#588: valid polygon when cw, not valid when ccw
------------------------+---------------------------------------------------
 Reporter:  olivier80   |       Owner:  geos-devel@…              
     Type:  defect      |      Status:  new                       
 Priority:  major       |   Milestone:  3.3.6                     
Component:  Default     |     Version:  3.3.5                     
 Severity:  Unassigned  |    Keywords:                            
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 Geos says this polygon is valid :

 {{{
 POLYGON ((
 -86.3958130146539250 114.3482370100377900,
 64.7285128575111490 156.9678884302379600,
 138.3490775437400700 43.1639042523018260,
 87.9271046586986810 -10.5302909001479570,
 87.9271046586986810 -10.5302909001479530,
 55.7321237336437390 -44.8146215164960250,
 -86.3958130146539250 114.3482370100377900))
 }}}


 Now, I reverse the points :

 {{{
 POLYGON ((
 -86.3958130146539250 114.3482370100377900,
 55.7321237336437390 -44.8146215164960250,
 87.9271046586986810 -10.5302909001479530,
 87.9271046586986810 -10.5302909001479570,
 138.3490775437400700 43.1639042523018260,
 64.7285128575111490 156.9678884302379600,
 -86.3958130146539250 114.3482370100377900))
 }}}


 Geos notices me "Self-intersection at or near point 87.927104658698681
 -10.530290900147953".

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Ticket URL: <http://trac.osgeo.org/geos/ticket/588>
GEOS <http://geos.refractions.net/>
GEOS (Geometry Engine - Open Source) is a C++ port of the Java Topology Suite (JTS).