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 [DPRG] math I once knew Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] Previous message: [DPRG] math I once knew Next message: [DPRG] math I once knew Subject: [DPRG] math I once knew From: Kipton Moravec kip at kdream.com Date: Fri Dec 20 10:34:01 CST 2002 ```Actually you can do it with 90 degrees and reflect it to all 4 points. There are a bunch of ways to do this and I will show the first one to pop in my head. I am assuming you have a sin() and cos() function. sin() is the ratio of opposite side from the angle over hypotenuse cos() is the ratio of adjacent side from the angle over the hypotenuse >From the center point, radius * sin(angle) = Y radius * cos(angle) = X If the angle goes through 0 through 90 degrees, then you reflect for the other 3 quadrants. (X,Y), (-X,Y), (X,-Y), (-X,-Y) This assumes the center of the circle is at 0,0. To have a different circle center, add the coordinates of the circle to the final result. (X+Xcenter,Y+Ycenter), (-X+Xcenter,Y+Ycenter), (X+Xcenter,-Y+Ycenter), (-X+Xcenter,-Y+Ycenter) Now you have the answer you are looking for.. Kip ----- Original Message ----- >From: "Sluggy!" To: "dprg" Sent: Friday, December 20, 2002 9:49 AM 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 > ``` Previous message: [DPRG] math I once knew Next message: [DPRG] math I once knew Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the DPRG mailing list