Clipping Algorithms

[luser- -droog]

Hodgman-Sutherland works on convex clipping regions,
requiring additional code to decompose concave paths
into multiple convex paths. Can operate upon a concave
path.

Weiler-Atherton works on concave clipping regions
and concave paths.

Vatti algorithm makes amazing claims, but I haven't dug
up any useful details, yet.


So far, I've just borrowed Cassleman's hodgman-sutherland
code. It's not clear to me how to coordinate the two
winding-rules with any of the above. Postscript, of course,
offers all its relevant operators in pairs: fill/eofill,
clip/eoclip.