I have an arbitrary collection of nodes connected by edges. I am trying to find a good way to tell if an edge/vertex is on the border or not.
The red nodes and blue lines are considered on border. Black lines and black nodes are considered interior.
All nodes are fixed to points on the Cartesian plane. It is a planar graph (no edges will cross over each other. They will intersect only at a node). Always one graph / connected shape in total (as opposed to multiple independently connected components).