# Implementing Midpoint Ellipse Algorithm in C++

Here is C++ code for midpoint ellipse algorithm.

```#include<iostream.h>
#include<dos.h>
#include<conio.h>
#include<math.h>
#include<graphics.h>
void display (int xs1, int ys1, int x, int y);
void ellips1(int xs1,int ys1,int rx, int ry)
{
int x,y;
float d1,d2,dx,dy;
x = 0;                  // take start position as (0,ry)
y = ry;             	// finding decision parameter d1
d1 = pow(ry,2) - (pow(rx,2) * ry) + (0.25 * pow(rx,2));
dx = 2 * pow(ry,2) * x;
dy = 2 * pow(rx,2) * y;
do                         // region one
{
display(xs1,ys1,x,y);
if(d1<0)
{
x++;
dx = dx + (2 * (pow(ry,2)));
d1 = d1 + dx +(pow(ry,2));
}
else
{
x++;
y--;
dx = dx + (2 * (pow(ry,2)));
dy = dy - (2 * (pow(rx,2)));
d1 = d1 + dx - dy + (pow(ry,2));
}
}while(dx<dy);      // change over condition for region-2
do                       // region two
{
display(xs1,ys1,x,y);
if(d2>0)
{
x = x;
y--;
dy = dy - (2 * (pow(rx,2)));
d2 = d2 - dy + pow(rx,2);
}
else
{
x++;
y--;
dy = dy - (2 * (pow(rx,2)));
dx = dx + (2 * (pow(ry,2)));
d2 = d2 +dx - dy + pow(rx,2);

}
}while(y>0);
}
void display(int xs,int ys,int x,int y)
{
putpixel(xs+x,ys+y,WHITE); // plot points by using 4 point symmetry
putpixel(xs-x,ys-y,WHITE);
putpixel(xs+x,ys-y,WHITE);
putpixel(xs-x,ys+y,WHITE);
}
int main(void)
{
int xs1,ys1;
float rx1,ry1;
int gd = DETECT,gm;           // Initialise the graphics system
initgraph(&gd,&gm,"c:\\tc\\bgi");
cout<<"\t\tMidpoint Ellipe Drawing Algorithm\n";
cout<<"Enter the Center Co-ordinates\n";
cout<<"xc = \t";
cin>>xs1;
cout<<"yc = \t";
cin>>ys1;
cin>>rx1;
cin>>ry1;
ellips1(xs1,ys1,rx1,ry1);
getch();
closegraph();
}
```

Output:

## One thought on “Implementing Midpoint Ellipse Algorithm in C++”

1. PL says:

bro make the code area wider and remove the scroll

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