On 11/17/18 8:37 PM, Graham Hardman wrote: > Hi, > > The documentation for the geopoly module states that the vertices must > be defined in a counter-clockwise order so that the interior of the > polygon is on the left of the element as it is drawn. > > However, I have discovered that a polygon transformed with geopoly_xform > can result in a polygon having vertices reading clockwise. For instance, > a polygon mirrored about either the x or y axis will produce this > effect. The geopoly module allows these transformed polygons to be added > to the table. If I then create an exact same polygon shape having > counterclockwise order for the vertices and use the geopoly_overlap > function to test it against the one with clockwise order I find the > result = 4, meaning the polygons are regarded as identical. > > My question then is, is it really necessary to ensure a counterclockwise > order when a polygon shape is entered for the first time in the table. > > regards, > > Graham > My guess would be that SOME operations will need the vertices in the right order, and others will work regardless of order.
-- Richard Damon _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
