In this article, we’ll be discussing meaning of window, viewport, window to viewport mapping and implementing the concept in form of code.
Window
It is a world coordinate. It is a region which is used for displaying an object.
Viewport
A viewport is considered as a device coordinate after it got normalized. It is a part of a screen in which object requires to display. Basically, world coordinate gets mapped into device coordinate. So that an object gets fitted in respective to a viewport.
What is Window to Viewport Transformation ?
It is the process of transforming world coordinate in respective to device coordinate. Usually, the size of a mapped object in the viewport is smaller than a window, but it can be possible to have a greater size than the Window.
C program for window to viewport transformation
Program:
#include<graphics.h>
#include<conio.h>
#include<stdio.h>
void main ()
{
int W_xmax, W_ymax, W_xmin, W_ymin;
int V_xmax, V_ymax, V_xmin, V_ymin;
float sx, sy;
int x, x1, x2, y, y1, y2;
int gr = DETECT, gm;
initgraph (&gr, &gm, "C:\\TURBOC3\\BGI");
printf ("\n****** Window to Viewport ***********\n");
printf ("Enter the coordinates for triangle \n x and y = ");
scanf ("%d %d", &x, &y);
printf ("\n x1 and y1 = ");
scanf ("%d %d", &x1, &y1);
printf ("\n x2 and y2 = ");
scanf ("%d %d", &x2, &y2);
printf ("Please enter Window coordinates \n First enter XMax, YMax =");
scanf ("%d %d", &W_xmax, &W_ymax);
printf ("\n Now, enter XMin, YMin =");
scanf ("%d %d", &W_xmin, &W_ymin);
cleardevice ();
delay (50);
//Window
rectangle (W_xmin, W_ymin, W_xmax, W_ymax);
outtextxy (W_xmin, W_ymin - 10, "Window");
//drawing a triangle
line (x, y, x1, y1);
line (x1, y1, x2, y2);
line (x2, y2, x, y);
// viewport
V_xmin = 300;
V_ymin = 30;
V_xmax = 550;
V_ymax = 350;
rectangle (V_xmin, V_ymin, V_xmax, V_ymax);
outtextxy (V_xmin, V_ymin - 10, "Viewport");
// calculatng Sx and Sy
sx = (float) (V_xmax - V_xmin) / (W_xmax - W_xmin);
sy = (float) (V_ymax - V_ymin) / (W_ymax - W_ymin);
x = V_xmin + (float) ((x - W_xmin) * sx);
x1 = V_xmin + (float) ((x1 - W_xmin) * sx);
x2 = V_xmin + (float) ((x2 - W_xmin) * sx);
y = V_ymin + (float) ((y - W_ymin) * sy);
y1 = V_ymin + (float) ((y1 - W_ymin) * sy);
y2 = V_ymin + (float) ((y2 - W_ymin) * sy);
// drawing triangle
line (x, y, x1, y1);
line (x1, y1, x2, y2);
line (x2, y2, x, y);
getch ();
closegraph ();
}
Output: 
