Implementation of Bresenhams algorithm - Ellipse

Implementation of Bresenhams algorithm - Ellipse

Enginer's Portal   1.c.) Implementation of Bresenhams algorithm - Ellipse  

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,"h:\\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;

/* REGION 1 */

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);

/* REGION 2*/

                  

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);

                    return;

}

Output :

Enter The Radius Value(Rx,Ry)           :     10      30

                   

Enter The xcenter and ycenter Values  :     300    150    

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