Date:	Sun, 2 Feb 1997 13:53:50 +0000 ( )
From:	Gurunandan R Bhat <grbhat AT unigoa DOT ernet DOT in>
To:	Benjamin D Chambers <chambersb AT juno DOT com>
Cc:	djgpp AT delorie DOT com
Subject:	Re: ellipses at an angle
In-Reply-To:	<19970201.211349.4943.1.chambersb@juno.com>
Message-Id:	<Pine.LNX.3.91.970202135028.202A-100000@aditya.unigoa.ernet.in>
Mime-Version:	1.0

On Sun, 2 Feb 1997, Benjamin D Chambers wrote:
> 
> On 1 Feb 1997 20:32:31 GMT hotpulp AT netidea DOT com writes:

> >I was wondering: how would I go about drawing an ellipse that has its
> >major and minor axis at an angle? If you're having trouble 


> Well, you could use the original definition of an ellipse (that is, from
> any point on the ellipse, the sum of the distances from that point to the
> two foci equals 1).  The math gets a little messy though.

its not very different from drawing a circle. for an ellipse, you do:

x = r1 * cos(t); y = r2 * sin (t)

if r1 is the same as r2 you get a circle. if you want a shifted ellipse, 
by an angle a say, do this:

x = r1 * cos(t + a) ; y = r2 * sin(t + a)

for a whole set of values of t from 0 to 360. there was a thread here 
earlier discussing how this could be done with integers. try the mail 
archives for that.

gurunandan bhat
goa, india

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