Roll No : 59 Name : Sayali Kulkarni
Date of Submission : 8 August 2024 Semester : 3
Subject Name : Computer Graphics Subject Code :
EXPERIMENT 3
Title IMPLEMENTATION OF BRESENHAM’S ALGORITHM FOR
CIRCLE
Objective To write a C Program for implementing Bresenham’s algorithm for circle
drawing.
Algorithm 1. Start
2. Input the radius r and the center (xc,yc) and obtain the first point
on the circumference of a circle centered on the origin as
(x0,y0) = (0,r)
3. Calculate the initial value of the decision parameter as
P0 = 5/4 – r
4. At each xk position, starting at k = 0, perform the following test
If Pk < 0, the next point along the circle centered on (0,0) is (xk+1,yk)
and Pk+1 = Pk +2xk+1+1
Otherwise, the next point along the circle is (xk+1,yk-1) and Pk+1 = Pk
+2xk+1+1- 2yk+1 where 2x k+1 = 2x k + 2 and 2yk+1 = 2y k - 2
5. Determine symmetry points in the remaining seven octants
6. Move each calculated pixel position (x,y) onto the circular path
centered on (xc,yc) and plot the coordinate value x = x+xc , y = y+ yc
7. Repeat steps 3 to 5 until x >= y
8. Stop
Program
#include<dos.h>
#include<stdio.h>
#include<conio.h>
#include<graphics.h>
void draw_circle (int,int,int);
void symmetry(int,int,int,int);
void main()
int xc,yc,R;
int gd=DETECT,gm;
initgraph(&gd,&gm,"C:\\TurboC3\\BGI");
printf("Xc=");
scanf("%d",&xc);
printf("Yc=");
scanf("%d",&yc);
printf("enter the radius of circle:");
scanf("%d",&R);
draw_circle(xc,yc,R);
getch();
closegraph();
void draw_circle(int xc,int yc,int rad)
int x=0;
int y=rad;
int p=1-rad;
symmetry(x,y,xc,yc);
for (x=0;y>x;x++)
if (p<0)
p+=2*x+3;
else{
p+=2*(x-y)+5;
y--;
symmetry(x,y,xc,yc);
delay(50);
void symmetry(int x, int y, int xc, int yc)
putpixel(xc+x,yc-y,GREEN); //for pixel(x,y)
delay(50);
putpixel(xc+y,yc-x,GREEN); //for pixel (y,x)
delay(50);
putpixel(xc+y,yc+x,GREEN); //for pixel (y,-x)
delay(50);
putpixel(xc+x,yc+y,GREEN); //for pixel(x,-y)
delay(50);
putpixel(xc-x,yc+y,GREEN); //for pixel(-x,-y)
delay(50);
putpixel(xc-y,yc+x,GREEN); //for pixel(-y,-x)
delay(50);
putpixel(xc-y,yc-x,GREEN); //for pixel(-y,x)
delay(50);
putpixel(xc-x,yc-y,GREEN); //for pixel(-x,y)
delay(50);
Output
Outcome Midpoint Circle Generation algorithm for drawing a line was written and
executed.
Conclusion Thus a C Program to implement Midpoint Circle Generation algorithm for
drawing a circle was written and executed.
