DDA algorithm :
1. Define the nodes, i.e end points in form of (x1,y1) and (x2,y2).
2. Calculate the distance between the two end points vertically and horizontally, i.e dx=|x1-x2| and dy=|y1-y2|.
3. Define new variable name ‘pixel’, and compare dx and dy values,
4. if dx > dy then
pixel=dx
else
pixel =dy.
5. dx=dx/pixel
and dy=dy/pixel
6. x=x1;
y=y1;
7. while (i<=pixel) compute the pixel and plot the pixel with x=x+dx and y=y+dy.
DDA ALGORITHM : PROGRAM
#include <graphics.h>
#include <stdio.h>
#include <math.h>
int main( )
{
float x,y,x1,y1,x2,y2,dx,dy,pixel;
int i,gd,gm;
printf("Enter the value of x1 : ");
scanf("%f",&x1);
printf("Enter the value of y1 : ");
scanf("%f",&y1);
printf("Enter the value of x2 : ");
scanf("%f",&x2);
printf("Enter the value of y1 : ");
scanf("%f",&y2);
detectgraph(&gd,&gm);
initgraph(&gd,&gm,"");
dx=abs(x2-x1);
dy=abs(y2-y1);
if(dx>=dy)
pixel=dx;
else
pixel=dy;
dx=dx/pixel;
dy=dy/pixel;
x=x1;
y=y1;
i=1;
while(i<=pixel)
{
putpixel(x,y,1);
x=x+dx;
y=y+dy;
i=i+1;
delay(100);
}
getch();
closegraph();
}
