Ex.No:7 ELLIPSE GENERATION ALGORITHM

AIM:

To write a program for ellipse generation.

ALGORITHM:

Step 1: Start.

Step 2: Initialize the graphics header files and functions.

Step 3: Declare the required variables and functions.

Step 4: Get the co-ordinates and radius of the ellipse.

Step 5: Draw the ellipse using the algorithm.

Step 6: Display the output.

Step 7: stop.

PROGRAM CODE:

```
#include <stdio.h>
#include <conio.h>
#include <math.h>
#include <graphics.h>
void main()
{
int gd=DETECT,gm;
int xcenter,ycenter,rx,ry;
int p,x,y,px,py,rx1,ry1,rx2,ry2;
initgraph(&gd,&gm,"c:\turboc3\bgi");
scanf("%d%d",&rx,&ry);
printf("n  Enter The xcenter and ycenter Values:");
scanf("%d%d",&xcenter,&ycenter);
ry1=ry*ry;
rx1=rx*rx;
ry2=2*ry1;
rx2=2*rx1;
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);
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();
}
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);
}
```

RESULT:

Thus the program for ellipse generation is written and executed successfully.