@Don: The sequence of points (x+a, y+b) generated by your algorithm
moves along the arc of the circle from theta = 90 degrees to theta =
45 degrees. Along this arc, the slope of the curve is -1 <= dy/dx <=
0. Thus, rather than moving from (x+a, y+b) to either (x+a+1, y+b) or
(x+a, y+b-1), you should be moving to either (x+a+1, y+b) or (x+a+1, y
+b-1). In words, you always increase a, and decrease b when that gets
you closer to the circle. Furthermore, you can algebraically simplify
the comparison so that no multiplications are required. See, e.g.,
http://homepage.smc.edu/kennedy_john/bcircle.pdf.
Dave
On Aug 5, 1:06 pm, Don <dondod...@gmail.com> wrote:
> // Draw a circle with center (x,y) and radius r
> circle(int x, int y, int r)
> {
> int a = 0;
> int b = r;
> while(a <= b)
> {
> // Draw the current location in all 4 quadrants
> plot(x+a, y+b);
> plot(x-a, y+b);
> plot(x+a, y-b);
> plot(x-a, y-b);
> plot(x+b, y+a);
> plot(x-b, y+a);
> plot(x+b, y-a);
> plot(x-b, y-a);
>
> // Look at two possible next points and pick the better
> int delta1 = r*r - (a+1)*(a+1) - b*b;
> int delta2 = r*r - a*a - (b-1)*(b-1);
> if (delta1*delta1 < delta2*delta2) ++a;
> else --b;
> }
>
> }
>
> On Aug 5, 8:38 am, rShetty <rajeevr...@gmail.com> wrote:
>
>
>
> > Write a routine to draw a circle (x ** 2 + y ** 2 = r ** 2) without
> > making use of any floating point
> > computations at all.- Hide quoted text -
>
> - Show quoted text -
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