I think that the main implication of allowing self intersecting edges of a polygon (like the possibly 5, probably 2 1/2 sided polygon from @davidhassell above) is people may use the wrong inside/outside algorithms and get unexpected results. The main ones are left-hand/right-hand, winding number, and counting crossings from infinity. [SVG explains this well](https://urldefense.us/v3/__https://www.w3.org/TR/2008/REC-SVGTiny12-20081222/painting.html*FillProperties__;Iw!!G2kpM7uM-TzIFchu!lIB46xeb5nsg2wV7IoDKCNIKLo7_2QKW5ufYHnvhvMZdkU_QvWQJFseoAfGRLiGTZSfr9KW70vQ$ ).
As people often choose the wrong algorithm anyway, I think allowing self-intersecting edges is OK, as it is the most general case, and "less is more". Whether implementations cope with multi-part, self-intersecting polygons is another issue. -- Reply to this email directly or view it on GitHub: https://urldefense.us/v3/__https://github.com/cf-convention/cf-conventions/issues/354*issuecomment-1033729094__;Iw!!G2kpM7uM-TzIFchu!lIB46xeb5nsg2wV7IoDKCNIKLo7_2QKW5ufYHnvhvMZdkU_QvWQJFseoAfGRLiGTZSfrlUYk9WQ$ You are receiving this because you are subscribed to this thread. Message ID: <cf-convention/cf-conventions/issues/354/[email protected]> This list forwards relevant notifications from Github. It is distinct from [email protected], although if you do nothing, a subscription to the UCAR list will result in a subscription to this list. To unsubscribe from this list only, send a message to [email protected].
