[DPRG] math I once knew
Subject: [DPRG] math I once knew
From: Dan Miner
miner at centtech.com
Date: Fri Dec 20 10:30:02 CST 2002
Dave,
That's close but you have sin/cos backwards.
x = r * cos (theta) + Xc
y = r * sin (theta) + Yc
where (Xc,Yc) is the center of the circle.
 Dan Miner
> Original Message
> From: Dave Hylands [mailto:dhylands at broadcom.com]
> Sent: Friday, December 20, 2002 10:07 AM
> To: 'Sluggy!'; dprg
> Subject: RE: [DPRG] math I once knew
>
>
> Hi Sluggy,
>
> I think that this is what you want:
>
> x = r * sin( theta )
> y = r * cos( theta )
>
> 
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
>
>
> > Original Message
> > From: Sluggy! [mailto:slugmusk at linuxlegend.com]
> > Sent: Friday, December 20, 2002 7:50 AM
> > To: dprg
> > Subject: [DPRG] math I once knew
> >
> >
> > Hey, folks...
> >
> > I have a question about some math I once knew but don't
> remember the
> > details of.
> >
> > I need to be able to plot X and Y coordinates for points
> laying in a
> > circle, in this case, the minute and hour points on a clock face.
> >
> > I used to do this all the time drawing circles and radar
> > screens and the
> > like on the Commodore 64 and even on my first IBM clone. Thus far,
> > everything I have found online seems to be a tool to give you
> > back the
> > picture, not the coordinates for the points.
> >
> > As I recall, the algorithm was such that you plug in the
> > coordinates of
> > the center point, units of diameter and an an angle in
> degrees for a
> > given point. To scribe a circle, you simply stepped through
> > the range on
> > 0 to 359 for the angle, drawing a line between each set of points.
> > Actually, I think there were two steps, one for the X
> coordinate, one
> > for the Y.
> >
> > Anyway, if anyone has a lead on this, it would be appreciated! :)
> >
> > Sluggy!
> >
> > _______________________________________________
> > DPRGlist mailing list
> > DPRGlist at dprg.org
> > http://nimon.ncc.com/mailman/listinfo/dprglist
> >
>
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