Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!gem.mps.ohio-state.edu!ginosko!uunet!cditi!josh
From: josh@cditi.UUCP (Josh Muskovitz)
Newsgroups: comp.graphics
Subject: Re: Need an algorithm to calculate area of polygons
Summary: it should be easy
Keywords: Polygon, algorithm
Message-ID: <619@cditi.UUCP>
Date: 4 Oct 89 16:46:09 GMT
References: <484@ctycal.UUCP>
Organization: CDI Technologies Inc., Grand Rapids, MI
Lines: 25

In article <484@ctycal.UUCP>, ingoldsb@ctycal.COM (Terry Ingoldsby) writes:
# I need an algorithm that will calculate (quickly)
# the area of an arbitrary polygon.  It would be *nice* if it could
# handle objects that include arcs, instead of lines for the edges of
# the `polygon'.  I have to be able to handle complicated cases like
# 
#          *--------------------------*
#          |         *________________|
#          |         |
#          |         *_______*
#          |                / 
#          *_____*        /
#               /       /      It's hard to draw diagonal lines!
#             */------*
# 
# -- 
#   Terry Ingoldsby                       ctycal!ingoldsb@calgary.UUCP

You should be able to pick an arbitrary point in the plane, and build a list
of triangles from every pair of adjacent endpoints.  The trick is determining
whether to add or subtract the area of the tirangle from the ongoing subtotal.

Does anyone have an easy way to determine this?

josh @ uunet!cditi