Article View: net.graphics
Article #1358Polygon breaking revisited
From: Timothy Beres
Date: Mon, 04 Aug 1986 19:33
Date: Mon, 04 Aug 1986 19:33
26 lines
1642 bytes
1642 bytes
Hi,
<thanks>
A while back I asked for some help on decomposing a polygon
into trapezoids. The response was excellent! Thank you everyone.
I ended up implementing "An algorithm for shading of regions on
vector display devices" by Brassel and Fegeas, ACM 1979. They
deal with trapezoidation of polygons in the first part of the paper.
It was pretty easy to figure out what had to be done, though *lots*
of examples and extrapolation were necessary to figure out some of the
little "exercise left to the reader*" items in the algorithm. I ended up
drawing lots of polygon chunks to identify these.
<followup request>
The above algorithm works fine for non-intersecting polygons;
now, does anyone know of an algorithm to seperate a polygon into non-
intersecting parts? The above algorithm will take it from there.
* Thank God for Calculus I: (Y - Y1) = M * (X - X1). Just be sure to
check for an infinite slope!
Tim
--
...!ihnp4!{duke, akgua}!ucf-cs!tslvax!tim Tim Beres
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site tslvax.UUCP Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!burl!ulysses!bellcore!whuxcc!lcuxlm!akgua!akguc!codas!peora!ucf-cs!tslvax!tim From: tim@tslvax.UUCP (Timothy Beres) Newsgroups: net.graphics Subject: Polygon breaking revisited Message-ID: <116@tslvax.UUCP> Date: Mon, 4-Aug-86 15:33:46 EDT Article-I.D.: tslvax.116 Posted: Mon Aug 4 15:33:46 1986 Date-Received: Thu, 7-Aug-86 01:59:32 EDT Distribution: net Organization: Tech-Source Labs, Altamonte Springs, Florida Lines: 26