Page 65 - DCAP313_LAB_ON_COMPUTER_GRAPHICS

Unit 4: Implementing Circle Algorithm

5. If D is outside the circle, choose (xn+1, yn–1) as the next pixel. Notes
(a) True (b) False

4.3 Bresenham’s Circle Drawing Algorithm

The following steps of Bresenham’s Circle Drawing 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
4.3.1 Bresenham’s Circle Drawing Algorithm Using C Programming
#include<stdio.h>
#include<conio.h>
#include<graphics.h>
void main()
{
int gd=DETECT, gm;
int x,y,r;
void cir(int, int, int);
printf(“Enter the Mid points and Radious:”);
scanf(“%d%d%d”, &x, &y, &r);
initgraph(&gd, &gm, “”);
cir(x, y, r);
getch();
closegraph();
}
void cir(int x 1 , int y 1 , int r)
{
int x=0,y=r,p=1–r;
void cliplot(int, int, int, int);
cliplot(x 1 , y 1 , x, y);
while(x<y)

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