# Computer Graphics Scan converting a Ellipse

Computer Graphics Scan converting a Ellipse with Computer Graphics Tutorial, Line Generation Algorithm, 2D Transformation, 3D Computer Graphics, Types of Curves, Surfaces, Computer Animation, Animation Techniques, Keyframing, Fractals etc.

# Scan Converting a Ellipse:

The ellipse is also a symmetric figure like a circle but is four-way symmetry rather than eight-way.

### Program to Implement Ellipse Drawing Algorithm:

```#include
#include
#include
#include
void disp();
float x,y;
intxc,yc;
void main()
{
intgd=DETECT,gm,a,b;
float p1,p2;
clrscr();
initgraph(&gd,&gm,"c:\\turboc3\\bgi");
printf("*** Ellipse Generating Algorithm ***\n");
printf("Enter the value of Xc\t");
scanf("%d",&xc);
printf("Enter the value of yc\t");
scanf("%d",&yc);
printf("Enter X axis length\t");
scanf("%d",&a);
printf("Enter Y axis length\t");
scanf("%d",&b);
x=0;y=b;
disp();
p1=(b*b)-(a*a*b)+(a*a)/4;
while((2.0*b*b*x)<=(2.0*a*a*y))
{
x++;
if(p1<=0)
p1=p1+(2.0*b*b*x)+(b*b);
else
{
y--;
p1=p1+(2.0*b*b*x)+(b*b)-(2.0*a*a*y);
}
disp();
x=-x;
disp();
x=-x;
delay(50);
}
x=a;
y=0;
disp();
p2=(a*a)+2.0*(b*b*a)+(b*b)/4;
while((2.0*b*b*x)>(2.0*a*a*y))
{
y++;
if(p2>0)
p2=p2+(a*a)-(2.0*a*a*y);
else
{
x--;
p2=p2+(2.0*b*b*x)-(2.0*a*a*y)+(a*a);
}
disp();
y=-y;
disp();
y=-y;
delay(50);
}
getch();
closegraph();
}
void disp()
{
putpixel(xc+x,yc+y,7);
putpixel(xc-x,yc+y,7);
putpixel(xc+x,yc-y,7);
putpixel(xc+x,yc-y,7);
}
```

Output:

There two methods of defining an Ellipse:

1. Polynomial Method of defining an Ellipse
2. Trigonometric method of defining an Ellipse

Next TopicPolynomial Method