[geos-devel] Ring winding?

[Ben Discoe]

I have a somewhat general question about how GEOS stores its polygons.

In the 'old' GIS style, ala ESRI Shapefile, the polygon consists of a single
set of points, where the exterior ring has a counter-clockwise winding, and
the interior rings have a clockwise winding.  Each ring is also closed
(first point is duplicated as the last) so that mathematically, the entire
set of points can be rendered as a single polygon without knowledge of rings
at all.

In the 'new' OGC style of separate rings, ala JTS/GEOS:
  1. Do the exterior and interior rings still differ in winding?  Or are
they all the same winding?
  2. Is each ring closed with a redundant point?

-Ben