Xref: utzoo comp.graphics:4473 sci.math:5687 comp.sources.wanted:6359
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!gatech!ukma!jgary
From: jgary@ms.uky.edu (James E. Gary)
Newsgroups: comp.graphics,sci.math,comp.sources.wanted
Subject: Re: looking for a fast ellipse algorithm
Summary: Hold on! He said _FAST_
Keywords: ellipse, graphics, circle
Message-ID: <11081@s.ms.uky.edu>
Date: 15 Feb 89 01:51:59 GMT
References: <399@peritek.UUCP> <1311@ndmath.UUCP>
Reply-To: jgary@ms.uky.edu (James E. Gary)
Organization: U of Kentucky, Mathematical Sciences
Lines: 17

In article <1311@ndmath.UUCP> krueger@ndmath.UUCP (Andreas Krueger) writes:
>In article <399@peritek.UUCP>, dig@peritek.UUCP (David Gotwisner) writes:
>> 
>> 	I am looking for an algorithm (or code) which will allow circle
>> generation onto a graphics device which drives a monitor with non-square
>> pixels.
>
[ lots of calculus stuff deleted ]

That is perfectly fine, but the title said he wanted a _FAST_ ellipse
algorithm. Almost any computer graphics book will contain Bresenham's
circle drawing algorithm which is very fast. It requires no trig function
evaluation, only addition, subtraction, and multiplication by 2 and 4,
which can be accomplished quickly by shifts. Uses only integer variables
also. It also takes advantage of the symmetry of the problem. I don't
think it gets no faster than that. If you can't find the algorithm in
a book somewhere, let me know and I'll post it. It is quite short.