C Program to implement Window to Viewport Transformation

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: