:py:mod:`gnome.utilities.geometry.poly_clockwise`
=================================================

.. py:module:: gnome.utilities.geometry.poly_clockwise

.. autoapi-nested-parse::

   code for checking if a polygon is cockwise or counter-clockwise

   There are two versions:

   is_clockwise_convex only works for convex polygons -- but is faster,
   it only needs to check three points.

   is_clockwise checks all points, but works for convex and cocave
     (note: that's the same as the area calculation)

   from:
   http://paulbourke.net/geometry/clockwise/



Module Contents
---------------


Functions
~~~~~~~~~

.. autoapisummary::

   gnome.utilities.geometry.poly_clockwise.is_clockwise
   gnome.utilities.geometry.poly_clockwise.is_clockwise_convex



.. py:function:: is_clockwise(poly)

   returns True if the polygon is clockwise ordered, false if not

   expects a sequence of tuples, or something like it (Nx2 array for instance),
   of the points:

   [ (x1, y1), (x2, y2), (x3, y3), ...(xi, yi) ]

   See: http://paulbourke.net/geometry/clockwise/


.. py:function:: is_clockwise_convex(poly)

   returns True if the polygon is clockwise ordered, false if not

   expects a sequence of tuples, or something like it, of the points:

   [ (x1, y1), (x2, y2), (x3, y3), ...(xi, yi) ]

   This only works for concave polygons. See:

   http://paulbourke.net/geometry/clockwise/