C Program to implement 2D Composite Transformation

Aim

To write a C program to implement 2D composite transformations such as consecutive translation, consecutive rotation, pivot point rotation and consecutive scaling.

Algorithm

Consecutive Translation

1. Input the co-ordinates of the object.
2. Draw the object on the screen.
3. Input the 1st and 2nd translation co-ordinates.
4. For each translation, add the translation co-ordinates to the object co-ordinates.
5. Draw the translated object on the screen.

Consecutive Rotation

1. Input the co-ordinates of the object.
2. Draw the object on the screen.
3. Input the 1st and 2nd rotation angles.
4. For each rotation, calculate r = (Ɵ * 3.14) / 180.
5. Calculate xn = xi * cos(r) - yi * sin(r).
6. Calculate yn = yi * cos(r) + xi * sin(r).
7. Draw the rotated object on the screen.

Pivot Point Rotation

1. Input the co-ordinates of the object.
2. Draw the object on the screen.
3. Input the pivot point co-ordinates.
4. Input the rotation angle.
5. Translate the object to the pivot point co-ordinates.
6. Rotate the object with the given angle.
7. Translate the rotated object back to the original co-ordinates.

Consecutive Scaling

1. Input the co-ordinates of the object.
2. Draw the object on the screen.
3. Input the scaling factors.
4. For each scaling transformation, multiply the object co-ordinates by the scaling factors.
5. Draw the scaled object on the screen.

Program Code

#include <stdio.h>

#include <conio.h>

#include <graphics.h>

#include <math.h>

void drawTri(int x[], int y[])

{

    int i;

    for (i = 0; i < 3; i++)

    {

        if (i == 2)

            line(x[i], y[i], x[0], y[0]);

        else

            line(x[i], y[i], x[i+1], y[i+1]);

    }

}

void main()

{

    int gd = DETECT, gm;

    int choice, x[3], y[3], i, j, n;

    int tx1, tx2, ty1, ty2, theta1, theta2, px, py, sx[10], sy[10];

    float tx, ty, r;

    clrscr();

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

    do

    {

        printf("1. Consecutive Translation\n2. Consecutive Rotation\n3. Pivot Point Rotation\n4. Consecutive Scaling\n5. Exit");

        printf("\nEnter your choice: ");

        scanf("%d", &choice);

        if (choice != 5)

        {

            printf("\nEnter the co-ordinates of Triangle...\n");

            for (i = 0; i < 3; i++)

            {

                printf("(x%d, y%d): ", i+1, i+1);

                scanf("%d %d", &x[i], &y[i]);

            }

        }

        switch (choice)

        {

        case 1:

            printf("\nEnter the 1st translation (tx1, ty1): ");

            scanf("%d %d", &tx1, &ty1);

            printf("\nEnter the 2nd translation (tx2, ty2): ");

            scanf("%d %d", &tx2, &ty2);

            cleardevice();

            drawTri(x, y);

            for (i = 0; i < 3; i++)

            {

                x[i] += tx1;

                y[i] += ty1;

            }

            setcolor(3);

            drawTri(x, y);

            for (i = 0; i < 3; i++)

            {

                x[i] += tx2;

                y[i] += ty2;

            }

            setcolor(GREEN);

            drawTri(x, y);

            getch();

            break;

        case 2:

            printf("\nEnter the 1st rotation angle: ");

            scanf("%d", &theta1);

            printf("Enter the 2nd rotation angle: ");

            scanf("%d", &theta2);

            cleardevice();

            drawTri(x, y);

            r = M_PI * theta1 / 180;

            for (i = 0; i < 3; i++)

            {

                tx = x[i];

                ty = y[i];

                x[i] = tx * cos(r) - ty * sin(r);

                y[i] = tx * sin(r) + ty * cos(r);

            }

            setcolor(3);

            drawTri(x, y);

            r = M_PI * theta2 / 180;

            for (i = 0; i < 3; i++)

            {

                tx = x[i];

                ty = y[i];

                x[i] = tx * cos(r) - ty * sin(r);

                y[i] = tx * sin(r) + ty * cos(r);

            }

            setcolor(GREEN);

            drawTri(x, y);

            getch();

            break;

        case 3:

            printf("\nEnter the pivot point (px, py): ");

            scanf("%d %d", &px, &py);

            printf("Enter the rotation angle: ");

            scanf("%d", &theta1);

            cleardevice();

            drawTri(x, y);

            for (i = 0; i < 3; i++)

            {

                x[i] = x[i] + px;

                y[i] = y[i] + py;

            }

            setcolor(3);

            drawTri(x, y);

            r = M_PI * theta1 / 180;

            for (i = 0; i < 3; i++)

            {

                tx = x[i];

                ty = y[i];

                x[i] = tx * cos(r) - ty * sin(r);

                y[i] = tx * sin(r) + ty * cos(r);

            }

            setcolor(BLUE);

            drawTri(x, y);

            for (i = 0; i < 3; i++)

            {

                x[i] = x[i] - px;

                y[i] = y[i] - py;

            }

            setcolor(GREEN);

            drawTri(x, y);

            getch();

            break;

        case 4:

            printf("\nEnter the number of scaling transformations: ");

            scanf("%d", &n);

            for (i = 0; i < n; i++)

            {

                printf("Enter the scaling unit (sx%d, sy%d): ", i+1, i+1);

                scanf("%d %d", &sx[i], &sy[i]);

            }

            cleardevice();

            drawTri(x, y);

            for (i = 0; i < n; i++)

            {

                for (j = 0; j < 3; j++)

                {

                    x[j] = x[j] * sx[i];

                    y[j] = y[j] * sy[i];

                }

                setcolor(i + 1);

                drawTri(x, y);

            }

            getch();

            break;

        default:

            break;

        }

        clrscr();

        cleardevice();

        setcolor(WHITE);

    } while (choice != 5);

    closegraph();

}