#include "stdio.h"

#include "conio.h"

#include "math.h"

#include "graphics.h"

main()

{

int gd=DETECT,gm;

int xcenter,ycenter,rx,ry;

int p,x,y,px,py,rx1,ry1,rx2,ry2;

initgraph(&gd,&gm,"c:\\tc\\bgi");

printf("Enter The Radius Value:\n");

scanf("%d%d",&rx,&ry);

printf("Enter The xcenter and ycenter Values:\n");

scanf("%d%d",&xcenter,&ycenter);

ry1=ry*ry;

rx1=rx*rx;

ry2=2*ry1;

rx2=2*rx1;

/* REGION 1 */

x=0;

y=ry;

plotpoints(xcenter,ycenter,x,y);

p=(ry1-rx1*ry+(0.25*rx1));

px=0;

py=rx2*y;

while(px<py)

{

x=x+1;

px=px+ry2;

if(p>=0)

y=y-1;

py=py-rx2;

if(p<0)

p=p+ry1+px;

else

p=p+ry1+px-py;

plotpoints(xcenter,ycenter,x,y);

/* REGION 2*/

p=(ry1*(x+0.5)*(x+0.5)+rx1*(y-1)*(y-1)-rx1*ry1); while(y>0)

{

y=y-1;

py=py-rx2;

if(p<=0)

{

x=x+1;

px=px+ry2;

}

if(p>0)

p=p+rx1-py;

else

p=p+rx1-py+px;

plotpoints(xcenter,ycenter,x,y);

}

}

getch();

return(0);

}

int plotpoints(int xcenter,int ycenter,int x,int y)

{

putpixel(xcenter+x,ycenter+y,6);

putpixel(xcenter-x,ycenter+y,6);

putpixel(xcenter+x,ycenter-y,6);

putpixel(xcenter-x,ycenter-y,6);

}