LINE DRAWING USING BRESENHAMS ALGORITHM

EX .NO:2                  LINE DRAWING USING BRESENHAMS ALGORITHM

Date:

AIM:

            To write a C program to draw a line using Bresenhams algorithm.

ALGORITHM:

Step1: Start.

Step2:Declare variables x,y,x1,y1,x2,y2,p,dx,dy and also declare gdriver=DETECT,    

          Mode.

Step3: Initialize the graphic mode with the path location in TC folder

Step4: Input the two line end-points and store the left end-points in (x1,y1).

Step5: Load (x1, y1) into the frame buffer; that is, plot the first point put x=x1,y=y1

Step6: Calculate dx=x2-x1 and dy=y2-y1, and obtain the initial value of decision  

          Parameter p as: a.p=(2dy-dx).

Step7: Starting from first point (x,y) perform the following test:

Step8: Repeat step 9 while(x<=x2).

Step9: If p<0, next point is (x+1,y) and p=(p+2dy).

Step10: Otherwise, the next point to plot is (x+1,y+1) and p=(p+2dy-2dx).

Step11: Place pixels using putpixel at points (x,y) in specified colour.

Step12: Close Graph

Step13: Stop.

PROGRAM

#include<stdio.h>

#include<conio.h>

#include<graphics.h>

void main()

{

int x,y,x1,y1,x2,y2,p,dx,dy;

intgdriver=DETECT,gmode;

initgraph(&gdriver,&gmode,"C:\\tc\\BGI:");

printf("\nEnter the x-coordinate of the first point ::");

scanf("%d",&x1);

printf("\nEnter the y-coordinate of the first point ::");

scanf("%d",&y1);

printf("\nEnter the x-coordinate of the second point ::");

scanf("%d",&x2);

printf("\nEnter the y-coordinate of the second point ::");

scanf("%d",&y2);

x=x1;

y=y1;

dx=x2-x1;

dy=y2-y1;

putpixel(x,y,2);

p=(dy-dx);

while(x<=x2)

{   if(p<0)

{   x=x+1;

    p=2*x-dx;

}

 else

{

x=x+1;

y=y+1;

p=p+2*dy;

}

putpixel(x,y,7);

}

getch();

closegraph();

}

OUTPUT:

Enter the x-coordinate of the first point: 200

Enter the y-coordinate of the first point: 300

Enter the x-coordinate of the second point: 300

Enter the y-coordinate of the second point: 300

RESULT:

                      Thus the program of line drawing using Bresenhams  algorithm is executed and output is obtained.