Develop the program for DDA Line drawing algorithm.

Digital Differential Analyzer (DDA) Algorithm

Step 1: Read the input of the 2 end points of the line as (x1, y1) & (x2, y2) such that x1 != x2 and y1 != y2

Step 2: Calculate dx = x2 – x1 and dy = y2 – y1

Step 3:

if(dx>=dy)

step=dx

else

step=dy

Step 4: xin = dx / step & yin = dy / step

Step 5: x = x1 + 0.5 & y = y1 + 0.5

Step 6: 

for(k = 0; k < step; k++)

{

x = x + xin

y = y + yin

putpixel(x, y)

}

 

Program

#include <graphics.h>

#include <stdio.h>

#include <math.h>

#include <dos.h>

 

void main( )

{

float x,y,x1,y1,x2,y2,dx,dy,step;

int i,gd=DETECT,gm;

 

initgraph(&gd,&gm,"c:\\turboc3\\bgi");

 

printf("Enter the value of x1 and y1 : ");

scanf("%f%f",&x1,&y1);

printf("Enter the value of x2 and y2: ");

scanf("%f%f",&x2,&y2);

 

dx=abs(x2-x1);

dy=abs(y2-y1);

 

if(dx>=dy)

step=dx;

else

step=dy;

 

dx=dx/step;

dy=dy/step;

 

x=x1;

y=y1;

 

i=1;

while(i<=step)

{

putpixel(x,y,5);

x=x+dx;

y=y+dy;

i=i+1;

delay(100);

}

 

closegraph();

}