I am trying to achieve the hexagon contour look you find in Civilization V:
I want to outline the area a unit can move to on a hexagon grid, so far I can get a list of all the tiles a unit can move to and from that select the tiles that are on the boundary, which looks like this:
Assume the list of boundary tiles are in random order. I can also get a list of all the corners on each hex. As you can see above the island in the middle would create a hole in the contour shape, Civ 5 also seems to handle these holes nicely: