C Program to implement Window to Viewport Transformation

Aim

To write a C graphics program to implement window to viewport transformation.

Algorithm

1. Initialize graphics mode.
2. Draw a window.
3. Get the object.
4. Translate the object together with its window until the lower left corner of the window is at origin.
5. Object and window are scaled until the window has the dimensions of the viewport.
6. Translate the viewport to its correct position on the screen.
7. Display the contents inside the viewport.

Program Code

#include <stdio.h>

#include <conio.h>

#include <graphics.h>

#include <math.h>

void main()

{

    float sx, sy;

    int w1, w2, w3, w4, x1, x2, x3, x4, y1, y2, y3, y4, v1, v2, v3, v4;

    int gd = DETECT, gm;

    initgraph(&gd, &gm, "C:\\TURBOC3\\BGI");

    printf("Enter coordinates for (x1,y1),(x2,y2),(x3,y3)\n");

    scanf("%d %d %d %d %d %d", &x1, &y1, &x2, &y2, &x3, &y3);

    cleardevice();

    w1 = 5;

    w2 = 5;

    w3 = 635;

    w4 = 465;

    rectangle(w1, w2, w3, w4);

    line(x1, y1, x2, y2);

    line(x2, y2, x3, y3);

    line(x3, y3, x1, y1);

    getch();

    v1 = 425;

    v2 = 75;

    v3 = 550;

    v4 = 250;

    sx = (float)(v3 - v1) / (w3 - w1);

    sy = (float)(v4 - v2) / (w4 - w2);

    rectangle(v1, v2, v3, v4);

    x1 = v1 + floor(((float)(x1 - w1) * sx) + 5);

    x2 = v1 + floor(((float)(x2 - w1) * sx) + 5);

    x3 = v1 + floor(((float)(x3 - w1) * sx) + 5);

    y1 = v2 + floor(((float)(y1 - w2) * sy) + 5);

    y2 = v2 + floor(((float)(y2 - w2) * sy) + 5);

    y3 = v2 + floor(((float)(y3 - w2) * sy) + 5);

    line(x1, y1, x2, y2);

    line(x2, y2, x3, y3);

    line(x3, y3, x1, y1);

    getch();

}

Output