Convex Hulls and Mesh Boundaries
================================

If the input is a vertex set (rather than a PSLG), Triangle produces its convex
hull as a by-product in the output's segments if you use the -c switch. There
are faster algorithms for finding a two-dimensional convex hull than triangulation,
of course, but this one comes for free. In the example below, the data `dots` is
read, and its convex hull produced in `dots.1`.

.. plot:: plot/convex_hull.py

If the input is an unconstrained mesh (you are using the -r switch but not the
-p switch), Triangle produces a list of its boundary edges (including hole
boundaries) as a by-product when you use the -c switch. If you also use the -p
switch, the output will contain all the segments from the input as well. For
example, consider the mesh described by `face.1`.


.. plot:: plot/face.py

::

    triangulate(get_data('face.1'), 'rc')
    triangulate(get_data('face.1'), 'rpc')

In each case, the boundary segments can be found in face.2.poly. 

.. plot:: plot/bndries.py