3D Transformation Graphics Program in C

Aim

To write a C program to implement 3D transformations such as translation, rotation and scaling of objects.

Algorithm:

·        Translation

1.     Read the co-ordinates (x, y, z) of the object.

2.     Display the original object.

3.     Read the translation vector (tx, ty, tz).

4.     Calculate the new co-ordinates as follows:

x’ = x + tx

y’ = y + ty

z’ = z + tz

5.     Display the translated object on the screen.

·        Rotation

1.     Read the co-ordinates (x, y, z) of the object.

2.     Display the original object.

3.     Read the rotation angle Ɵ.

4.     For rotation about z-axis, calculate new co-ordinates as follows:

x’ = x * cos(Ɵ) – y * sin(Ɵ)

y’ = x * sin(Ɵ) + y * cos(Ɵ)

z’ = z

5.     Display the object after rotation about z-axis.

6.     For rotation about x-axis, calculate new co-ordinates as follows:

x’ = x

y’ = y * cos(Ɵ) – z * sin(Ɵ)

z’ = y * sin(Ɵ) + z * cos(Ɵ)

7.     Display the object after rotation about x-axis.

8.     For rotation about y-axis, calculate new co-ordinates as follows:

x’ = z * sin(Ɵ) + x * cos(Ɵ)

y’ = y

z’ = z * cos(Ɵ) – x * sin(Ɵ)

9.     Display the object after rotation about y-axis.

10.  Stop

·        Scaling

1.     Read the co-ordinates (x, y, z) of the object.

2.     Display the original object.

3.     Read the scaling factors (sx, sy, sz).

4.     Calculate the new co-ordinates as follows:

x’ = x * sx

y’ = y * sy

z’ = z * sz

5.     Display the scaled object on the screen.

Program Code

#include <stdio.h>

#include <conio.h>

#include <graphics.h>

#include <math.h>

int maxx, maxy, midx, midy;

void drawAxis()

{

    setcolor(CYAN);

    line(midx, 0, midx, maxy);

    line(0, midy, maxx, midy);

    setcolor(WHITE);

}

void main()

{

    int gd = DETECT, gm, choice;

    int tx, ty, sx, sy, sz, ang, r, x1, x2, y1, y2;

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

    setfillstyle(3, 25);

    maxx = getmaxx();

    maxy = getmaxy();

    midx = maxx / 2;

    midy = maxy / 2;

    do

    {

        outtextxy(20, 150, "ORIGINAL OBJECT");

        drawAxis();

        bar3d(midx + 100, midy - 20, midx + 60, midy - 90, 20, 1);

        printf("1. Translation\n2. Rotation\n3. Scaling\n4. Exit");

        printf("\nEnter your choice: ");

        scanf("%d", &choice);

        switch (choice)

        {

        case 1:

            printf("\nEnter the Translation vector (tx, ty): ");

            scanf("%d%d", &tx, &ty);

            cleardevice();

            outtextxy(100, 50, "TRANSLATION");

            drawAxis();

            bar3d(midx + 100, midy - 20, midx + 60, midy - 90, 20, 1);

            setcolor(GREEN);

            bar3d(midx + (tx+100), midy - (ty+20), midx + (tx+60), midy - (ty+90), 20, 1);

            getch();

            break;

        case 2:

            printf("\nEnter the Rotation angle: ");

            scanf("%d", &ang);

            r = ang * 3.14 / 180;

            x1 = 100 * cos(r) - 20 * sin(r);

            y1 = 100 * sin(r) + 20 * sin(r);

            x2 = 60 * cos(r) - 90 * sin(r);

            y2 = 60 * sin(r) + 90 * sin(r);

            cleardevice();

            drawAxis();

            outtextxy(50, 50, "Rotation about Z axis");

            bar3d(midx + 100, midy - 20, midx + 60, midy - 90, 20, 1);

            setcolor(GREEN);

            bar3d(midx + x1, midy - y1, midx + x2, midy - y2, 20, 1);

            getch();

            cleardevice();

            drawAxis();

            outtextxy(50, 50, "Rotation about X axis");

            bar3d(midx + 100, midy - 20, midx + 60, midy - 90, 20, 1);

            setcolor(GREEN);

            bar3d(midx + 100, midy - x1, midx + 60, midy - x2, 20, 1);

            getch();

            cleardevice();

            drawAxis();

            outtextxy(50, 50, "Rotation about Y axis");

            bar3d(midx + 100, midy - 20, midx + 60, midy - 90, 20, 1);

            setcolor(GREEN);

            bar3d(midx + x1, midy - 20, midx + x2, midy - 90, 20, 1);

            getch();

            break;

        case 3:

            printf("\nEnter the Scaling Factor (sx, sy, sz): ");

            scanf("%d %d %d", &sx, &sy, &sz);

            cleardevice();

            outtextxy(100, 50, "SCALING");

            drawAxis();

            bar3d(midx + 100, midy - 20, midx + 60, midy - 90, 20, 1);

            setcolor(GREEN);

            bar3d(midx+(sx*100), midy-(sy*20), midx+(sx*60), midy-(sy*90), 20*sz, 1);

            getch();

            break;

        default:

            break;

        }

        clrscr();

        cleardevice();

        setcolor(WHITE);

    } while (choice != 4);

    closegraph();

}