Bresenham’s algorithm for ellipse coding c program computer graphics

 Bresenham’s  algorithm for ellipse coding c program computer graphics

BRESENHAM’S ALGORITHM


AIM :

     To  implement the Bresenham’s  algorithm for ellipse using a c coding.


ELLIPSE :


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 :

#include "stdio.h"
#include "conio.h"
#include "math.h"
#include "graphics.h"
main()
{
    int gd=DETECT,gm;
    int xcenter,ycenter,rx,ry;
    int p,x,y,px,py,rx1,ry1,rx2,ry2;
    initgraph(&gd,&gm,"c:\\tc\\bgi");
    printf("Enter The Radius Value:\n");
    scanf("%d%d",&rx,&ry);
    printf("Enter The xcenter and ycenter Values:\n");
    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();
    return(0);
            }

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);

}




OUTPUT :

Enter The Radius Value(Rx,Ry)           :  10  30
   
Enter The xcenter and ycenter Values  :  300  150

RESULT:    

                  The Bresenham’s algorithm for ellipse was executed and verified     

                  successfully.