C++ Program to implement translation in graphics

 A translation is an affine transformation but not a linear transformation, homogeneous coordinates are normally used to represent the translation operator by a matrix and thus to make it linear. Thus we write the 3-dimensional vector w = (w_x, w_y, w_z) using 4 homogeneous coordinates as 
w = (w_x, w_y, w_z, 1).^[1]

https://en.wikipedia.org/wiki/2D_computer_graphics

Program

#include <iostream.h>
#include <conio.h>
#include <graphics.h>
void main()
{
int gd=DETECT,gm,x1,x2,y1,y2,tx,ty;
initgraph(&gd,&gm,"C:\\Tc\\BGI");
cout<<"Enter the first co-ordinate of a line:";
cin>>x1>>y1;
cout<<"Enter the second co-ordinate of a line:";
cin>>x2>>y2;
line(x1,y1,x2,y2);
cout<<"Enter the translation vector:";
cin>>tx>>ty;
setcolor(RED);
x1=x1+tx;
y1=y1+ty;
x2=x2+tx;
y2=y2+ty;
line(x1,y1,x2,y2);
getch();
closegraph();
}