20 void MP_Ellipse(int xc , int yc , int a, int b)
21 {
22 double sqa = a * a;
23 double sqb = b * b;
24
25 double d = sqb + sqa * (-b + 0.25);
26 int x = 0;
27 int y = b;
28 EllipsePlot(xc, yc, x, y);
29 while( sqb * (x + 1) < sqa * (y - 0.5))
30 {
31 if (d < 0)
32 {
33 d += sqb * (2 * x + 3);
34 }
35 else
36 {
37 d += (sqb * (2 * x + 3) + sqa * (-2 * y + 2));
38 y--;
39 }
40 x++;
41 EllipsePlot(xc, yc, x, y);
42 }
43 d = (b * (x + 0.5)) * 2 + (a * (y - 1)) * 2 - (a * b) * 2;
44 while(y > 0)
45 {
46 if (d < 0)
47 {
48 d += sqb * (2 * x + 2) + sqa * (-2 * y + 3);
49 x++;
50 }
51 else
52 {
53 d += sqa * (-2 * y + 3);
54 }
55 y--;
56 EllipsePlot(xc, yc, x, y);
57 }
58 }
