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Ellipse Using Mid Point Algorithm C++ Program

#include<conio.h>
#include<stdio.h>
#include<Graphics.h>

void main() {
int gd = DETECT,gm;
initgraph(&gd,&gm,"C:\\TC\\BGI");

int xc,yc,x,y;
long rx,ry;
float d;

printf("Enter Coordinates of Centre of Ellipse: ");
scanf("%d%d",&xc,&yc);
printf("Enter Radius along X-AXIS: ");
scanf("%ld",&rx);
printf("Enter Radius along Y-AXIS: ");
scanf("%ld",&ry);

//Region 1
d=((ry*ry)-(rx*rx*ry)+(rx*rx))/4;
x=0;       y=ry;

while(2.0*ry*ry*x < = 2.0*rx*rx*y)
{
       if(d < 0)
       {
             x++;
             d = d+(2*ry*ry*x)+(ry*ry);
       }
       else
       {
             x++;y--;
             d = d+(2*ry*ry*x)-(2*rx*rx*y)-(ry*ry);
       }
       putpixel(xc+x,yc+y,15);
       putpixel(xc+x,yc-y,15);
       putpixel(xc-x,yc+y,15);
       putpixel(xc-x,yc-y,15);
}

//Region 2

d =ry*ry*(x+0.5)*(x+0.5) + (rx*rx*(y-1)*(y-1)) - (rx*rx*ry*ry);

   while(y > 0)
   {
       if(d<= 0)
       {
             x++;    y--;
             d = d + (2*ry*ry*x) - (2*rx*rx*y) + (rx*rx);
       }
       else
       {
             y--;
             d = d - (2*rx*rx*y) + (rx*rx);
       }

       putpixel (xc+x,yc+y, 15 );
       putpixel (xc+x,yc-y, 15 );
       putpixel (xc-x,yc+y, 15 );
       putpixel (xc-x,yc-y, 15 );
   }
getch();
closegraph();
}

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