C Program for BRESENHAM’S CIRCLE DRAWING ALGORITHM

            

To draw a circle using Bresenham circle drawing algorithm.

ALGORITHM:

1.      Start

2.      Initialize the graphics mode.

3.      Read the radius of the circle

4.      Initialize the graphics mode.

5.      Initialize starting points x=0,y=r

6.      Initialize decision variable d=3 – 2 * r

7.      plot(x,y)

a.        plot eight points (+x,+y),(+x,-y),(-x,+y),(-x,-y),(+y,+x) ,(+y,-x),

       (-y,+x),(-y,-x)

8.      If d< =0  , d = d + 4 * x +6  else {d = d + 4 (x-y) +10, y = y-1}

9.      x=x+1

10.  insert delay to observe the drawing process

11.  Repeat 6- 10 until x<y

PROGRAM:

#include<stdio.h>

#include<graphics.h>

#include<conio.h>

main()

{

  int gd=DETECT,gm,x=0,radius,xc,yc,y,p;

  void circleplotpoint(int,int,int,int);

  initgraph(&gd,&gm,"");

  setbkcolor(15);

  setcolor(BLUE);

   outtextxy(160,10,"BRESENHAM'S CIRCLE GENERATION ALGORITHM");

   printf("\n\nEnter The Values (xc,yc):");

   scanf("%d %d",&xc,&yc);

   printf("\n\nEnter The Radius :");

   scanf("%d",&radius);

   cleardevice();

   outtextxy(160,10,"BRESENHAM'S CIRCLE GENERATION ALGORITHM");

   y=radius;

   p=3-2*radius;

   while(x<y)

   {

      x++;

      if(p<0) p+=4*x+6;

      else

      {

            y--;

            p+=4*(x-y)+10;

      }

      circleplotpoint(xc,yc,x,y);

      delay(200);

    }

    getch();

    closegraph();

}

void circleplotpoint(int xc,int yc,int x,int y)

{

  putpixel(xc+x,yc+y,3);

  putpixel(xc-x,yc+y,4);

  putpixel(xc+x,yc-y,5);

  putpixel(xc-x,yc-y,8);

  putpixel(xc+y,yc+x,3);

  putpixel(xc-y,yc+x,4);

  putpixel(xc+y,yc-x,5);

  putpixel(xc-y,yc-x,8);

}

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