#include<stdio.h>
#include<graphics.h>
#include<math.h>
main()
{
long d1,d2;
int i,gd,gm,x,y;
long rx, ry, rxsq,rysq,tworxsq,tworysq,dx,dy;
/* Read the radius x and y
---------------------------- */
printf("Enter the x radius of the ellipse :");
scanf("%ld",&rx);
printf("Enter the y radius of the ellipse :");
scanf("%ld",&ry);
/* initialise graphics
------------------------ */
detectgraph(&gd,&gm);
initgraph(&gd,&gm,"C:\\TC\\BGI");
rxsq = rx * rx;
rysq = ry * ry;
tworxsq = 2 * rxsq;
tworysq = 2 * rysq;
x = 0;
y = ry;
d1 = rysq - rxsq * ry + (0.25 * rxsq) ;
dx = tworysq * x;
dy = tworxsq * y;
do
{
putpixel(200+x,200+y,15);
putpixel(200-x,200-y,15);
putpixel(200+x,200-y,15);
putpixel(200-x,200+y,15);
if (d1 < 0)
{
x = x + 1;
y = y;
dx = dx + tworysq;
d1 = d1 + dx + rysq;
}
else
{
x = x + 1;
y = y - 1;
dx = dx + tworysq;
dy = dy - tworxsq;
d1 = d1 + dx - dy + rysq;
}
delay(10);
}
while( dx < dy);
d2 = rysq* (x+0.5) * (x+0.5)+rxsq*(y-1)*(y-1)-rxsq*rysq ;
do
{
putpixel(200+x,200+y,15);
putpixel(200-x,200-y,15);
putpixel(200+x,200-y,15);
putpixel(200-x,200+y,15);
if(d2 > 0)
{
x = x;
y = y -1;
dy = dy -tworxsq;
d2 = d2 - dy + rxsq;
}
else
{
x = x+1;
y = y -1;
dy = dy -tworxsq;
dx = dx + tworysq;
d2 = d2 + dx - dy + rxsq;
}
}
while (y > 0);
getch();
closegraph();
}
SAMPLE OUTPUT:
