Homogeneous Transformations

#include <stdio.h>
#include <conio.h>
#include <graphics.h>
#include <math.h>

//Change R to change the number of points of polynomial
#define R 3
#define C 3
#define PI 3.142

float c[R][C]={{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};
float temp[R][C]={{1, 0, 0}, {0, 1, 0}, {0, 0, 1}};

void printM(float a[][C]){
    int i, j;
    for(i = 0; i < R; i++){
        for(j = 0; j < C; j++){
            printf("%.2f\t\t", a[i][j]);
        }
        printf("\n");
    }
    printf("\n\n");
}

void initializeM(float obj[][C]){
    /*int i, j;
    printf("Enter the points:-\n");
    for(i = 0; i < R; i++){
        for(j = 0; j < C; j++){
            if(j<C-1)  scanf("%f", &obj[i][j]);
            else obj[i][C-1] = 1.00;
        }
        printf("\n");
    } */
    obj[0][0]=100;
    obj[0][1]=100;
    obj[0][2]=1;

    obj[1][0]=200;
    obj[1][1]=100;
    obj[1][2]=1;

    obj[2][0]=150;
    obj[2][1]=50;
    obj[2][2]=1;
}

void mul(float a[][C], float b[][C]){
    int i, j, k;
    float sum;
    for(i = 0; i < R; i++){
        for(j = 0;  j < C; j++){
            sum = 0;
            for(k = 0; k < R; k++)
                sum += a[i][k]*b[k][j];
            temp[i][j] = sum;
        }
    }
    for(i=0; i < R; i++)
        for(j=0; j < C; j++)
            c[i][j] = temp[i][j];
}

void startGraphics(){
    int gd=DETECT, gm;
    initgraph(&gd, &gm, "C:\\TURBOC3\\BGI");
}

void showGraphically(float a[][C]){
    int i, j;
    for(i=0, j=1; i<R-1; i++, j++)
        line((int)a[i][0], (int)a[i][1], (int)a[j][0], (int)a[j][1]);
    line((int)a[0][0], (int)a[0][1], (int)a[R-1][0], (int)a[R-1][1]);
}

int main(){
    int choice, choiceref;
    float t;
    float obj[R][C];
    float trans[R][C] = {{1, 0, 0} , {0, 1, 0} , {0, 0, 1}};
    float scale[R][C] = {{0, 0, 0} , {0, 0, 0} , {0, 0, 1}};
    float rot[R][C] = {{0, 0, 0} , {0, 0, 0} , {0, 0, 1}};
    float shear[R][C] = {{1, 0, 0} , {0, 1, 0} , {0, 0, 1}};
    float reflect[R][C] = {{1, 0, 0} , {0, 1, 0} , {0, 0, 1}};
    clrscr();

    initializeM(obj);
    printM(c);
    while(1){
        printf("1.Tranlate 2.Scale 3.Rotate 4.Shear 5.Reflect 6.Exit: ");
        scanf("%d", &choice);
        switch(choice){
            case 1: printf("\nEnter tx and ty values.\n");
                    scanf("%f%f", &trans[2][0], &trans[2][1]);
                    printM(trans);
                    mul(c, trans);
                    break;
            case 2: printf("Enter sx and sy values.\n");
                    scanf("%f%f", &scale[0][0], &scale[1][1]);
                    printM(scale);
                    mul(c, scale);
                    break;
            case 3: printf("Enter theta's value:");
                    scanf("%f", &t);
                    rot[0][0]=cos(t*PI/180);
                    rot[0][1]=sin(t*PI/180);
                    rot[1][0]=-sin(t*PI/180);
                    rot[1][1]=cos(t*PI/180);
                    printM(rot);
                    mul(c, rot);
                    break;
            case 4: printf("Enter shx and shy values.\n");
                    scanf("%f%f", &shear[1][0], &shear[0][1]);
                    printM(shear);
                    mul(c, shear);
                    break;
            case 5: printf("Reflection about 1.X-axis 2.Y-axis 3.Origin 4.y=x 5.y=-x: ");
                    scanf("%d", &choiceref);
                    switch(choiceref){
                        case 1: reflect[1][1] = -1; break;
                        case 2: reflect[0][0] = -1; break;
                        case 3: reflect[1][1] = -1; reflect[0][0] = -1; break;
                        case 4: reflect[1][1] = 0; reflect[0][0] = 0; reflect[0][1] = 1; reflect[1][0] = 1; break;
                        case 5: reflect[1][1] = 0; reflect[0][0] = 0; reflect[0][1] = -1; reflect[1][0] = -1; break;
                        default: printf("Invalid option!");
                    }
                    printM(reflect);
                    mul(c, reflect);
                    reflect[0][0]=1;
                    reflect[0][1]=0;
                    reflect[0][2]=0;

                    reflect[1][0]=0;
                    reflect[1][1]=1;
                    reflect[1][2]=0;

                    reflect[2][0]=0;
                    reflect[2][1]=0;
                    reflect[2][2]=1;
                    break;
            case 6: goto out;
            default: printf("Enter a valid input(1 to 6)\n");
        }
        printM(c);
    }
    out: mul(obj, c);
    printM(c);
    getch();
    startGraphics();
    showGraphically(obj);
    getch();
    showGraphically(c);
    getch();
    closegraph();
    return 0;
}