In an ESRI shapefile, a polygon can have multiple parts. Each part is a closed ring. Rings that wrap clockwise are... um... rings. Rings that wrap counterclockwise are holes in (some upstream) rings.
Suppose I want a polygon to represent the land portions of: a) a state, b) with a lake in the state, and c) with an island on the lake.
Would it be common to represent this as a single polygon with three parts: a) a clockwise ring for the state, b) a counterclockwise ring for the lake, and c) another clockwise ring for the island?
Similarly, a state with two lakes each with one island would have 5 parts.
If so, do I have to figure out, own my own, which parts are clockwise and which are counterclockwise, and which parts are contained in other parts; or is there some more direct way of figuring this out?
If not, what is the proper representation?
I am processing the shapefile on my own (in C#) to learn how it's done. I'm not really looking for links to libraries that do everything for me.