/* DDA Line Drawing Algorithm */

#include <graphics.h>
#include <stdio.h>
#include <math.h>
#include <conio.h>

void ddaLine(int x1,int y1,int x2,int y2)
{
	float x=x1,y=y1,dx,dy;
	int length,i;

	putpixel(x1,y1,WHITE);

	if(abs(x2-x1)>=abs(y2-y1))
		length=abs(x2-x1);
	else
		length=abs(y2-y1);
	dx=(float)(x2-x1)/length;
	dy=(float)(y2-y1)/length;
	for(i=1;i<=length;i++)
	{
		x=x+dx;
		y=y+dy;
		putpixel((int)x,(int)y,WHITE);
	}
}

void main()
{
	int x1,y1,x2,y2;
	int gdriver = DETECT, gmode;
	initgraph(&gdriver, &gmode, "");

	printf("Enter the starting co-ordinates: ");
	scanf("%d %d",&x1,&y1);
	printf("Enter the ending co-ordinates:   ");
	scanf("%d %d",&x2,&y2);

	ddaLine(x1,y1,x2,y2);
	getch();
}