Implementation of Mid-point Ellipse algorithm with source code in C/C++.

//Mid Point Ellipse

#include<stdio.h>

#include<conio.h>

#include<graphics.h>

#include<math.h>

int ellips(int ,int ,int ,int);

 

int main(void)

{

 

    int gdriver=DETECT,errorcode,gmode;

    int rx,ry,i,x,y;

    start:

    initgraph(&gdriver, &gmode, "C:\\TC\\BGI");

    errorcode=graphresult();

    if(errorcode!=grOk)

    {

        printf("Error");

    }

 

    setcolor(3);

    rectangle(0,70,getmaxx(),getmaxy());

    line(0,getmaxy()/2+35,getmaxx(),getmaxy()/2+35);

    line(getmaxx()/2,70,getmaxx()/2,getmaxy());

 

    printf("Enter the values of rx and ry: ");

    scanf("%d %d",&rx,&ry);

    printf("Enter the coordinates for the center: ");

    scanf("%d %d",&x,&y);

 

    ellips(rx,ry,x,y);

    printf("Press 1 to continue: ");

    scanf("%d",&i);

    if(i==1)

    goto start;

 

return;

 

}

int ellips(int rx,int ry,int x,int y)

{

 

int p1,p2,x1,y1;

x1=x;

y1=y;

x=0;

y=ry;

 

    p1=(ry*ry)-(rx*rx*ry)+(rx*rx)/4;

     //region 1

 

    while((2*ry*ry*x)>=(2*rx*rx*y))

    {

        if(p1<0)

        {

            x++;

            putpixel(getmaxx()/2+x+x1,getmaxy()/2+y+y1+35,3);

            putpixel(getmaxx()/2+x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2+y+y1+35,3);

            p1=p1+2*(ry*ry*x)+(ry*ry);

        }

        else if(p1>=0)

        {

            x++;

            y--;

            putpixel(getmaxx()/2+x+x1,getmaxy()/2+y+y1+35,3);

            putpixel(getmaxx()/2+x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2+y+y1+35,3);

            p1=p1+(2*ry*ry*x)-(2*rx*rx*y)+(ry*ry);

        }

    }

    //region2

 

    p2=(ry*ry)*(x+(1/2))^2+(rx*ry*(y-1)^2)-(rx*rx*ry*ry);

 

    while(y>0)

    {

        if(p2>0)

        {

            y--;

            putpixel(getmaxx()/2+x+x1,getmaxy()/2+y+y1+35,3);

            putpixel(getmaxx()/2+x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2+y+y1+35,3);

 

            p2=p2-2*(ry^2)*y+rx^2;

        }

        else if(p2<=0)

        {

            x++;

            y--;

            putpixel(getmaxx()/2+x+x1,getmaxy()/2+y+y1+35,3);

            putpixel(getmaxx()/2+x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2-y+y1+35,3);

            putpixel(getmaxx()/2-x+x1,getmaxy()/2+y+y1+35,3);

 

            p2=p2+2*(ry^2)*x-2*(rx^2)*y+rx^2;

        }

    }

return ;

}