3 D Translation, Rotation and Scaling

#include <graphics.h>  

#include <conio.h>  

#include <math.h>  

#include <iostream.h>  

float p[8][4]={0,0,0,100,  
          100,0,0,1,  
          0,100,0,1,  
          100,100,0,1,  
          0,0,100,1,  
          100,0,100,1,  
          0,100,100,1,  
          100,100,100,1};  
void change(float b[4][4])  
{  
  for (int i=0;i<8;i++)  
  {  
    float q[4];  
    q[0]=p[i][0]*b[0][0]+p[i][1]*b[0][1]+p[i][2]*b[0][2]+p[1][3]*b[0][3];  
    q[1]=p[i][0]*b[1][0]+p[i][1]*b[1][1]+p[i][2]*b[1][2]+p[1][3]*b[1][3];  
    q[2]=p[i][0]*b[2][0]+p[i][1]*b[2][1]+p[i][2]*b[2][2]+p[1][3]*b[2][3];  
    q[3]=p[i][0]*b[3][0]+p[i][1]*b[3][1]+p[i][2]*b[3][2]+p[1][3]*b[3][3];  
    for (int j=0;j<4;j++)  
      p[i][j]=q[j]/q[3];  
  }  
}  
void scale(float x, float y, float z)  
{  
   float b[4][4]={x,0,0,0,0,y,0,0,0,0,z,0,0,0,0,1};  
   change(b);  
}  
void rotx(float a)  
{  
   float b[4][4]={1,0,0,0,  
          0,cos(a),-sin(a),0,  
          0,sin(a),cos(a),0,  
          0,0,0,1};  
   change(b);  
}  
void roty(float a)  
{  
   float b[4][4]={cos(a),0,sin(a),0,  
          0,1,0,0,  
          -sin(a),0,cos(a),0,  
          0,0,0,1};  
   change(b);  
}  
void rotz(float a)  
{  
   float b[4][4]={cos(a),-sin(a),0,0,  
          sin(a),cos(a),0,0,  
          0,0,1,0,  
          0,0,0,1};  
   change(b);  
}  
void disp()  
{  
  line(p[0][0]+getmaxx()/2,getmaxy()/2-p[0][1],p[1][0]+getmaxx()/2,getmaxy()/2-p[1][1]);  
  line(p[0][0]+getmaxx()/2,getmaxy()/2-p[0][1],p[2][0]+getmaxx()/2,getmaxy()/2-p[2][1]);  
  line(p[3][0]+getmaxx()/2,getmaxy()/2-p[3][1],p[1][0]+getmaxx()/2,getmaxy()/2-p[1][1]);  
  line(p[3][0]+getmaxx()/2,getmaxy()/2-p[3][1],p[2][0]+getmaxx()/2,getmaxy()/2-p[2][1]);  
  int c=4;  
  line(p[0+c][0]+getmaxx()/2,getmaxy()/2-p[0+c][1],p[1+c][0]+getmaxx()/2,getmaxy()/2-p[1+c][1]);  
  line(p[0+c][0]+getmaxx()/2,getmaxy()/2-p[0+c][1],p[2+c][0]+getmaxx()/2,getmaxy()/2-p[2+c][1]);  
  line(p[3+c][0]+getmaxx()/2,getmaxy()/2-p[3+c][1],p[1+c][0]+getmaxx()/2,getmaxy()/2-p[1+c][1]);  
  line(p[3+c][0]+getmaxx()/2,getmaxy()/2-p[3+c][1],p[2+c][0]+getmaxx()/2,getmaxy()/2-p[2+c][1]);  
  line(p[1][0]+getmaxx()/2,getmaxy()/2-p[1][1],p[1+c][0]+getmaxx()/2,getmaxy()/2-p[1+c][1]);  
  line(p[2][0]+getmaxx()/2,getmaxy()/2-p[2][1],p[2+c][0]+getmaxx()/2,getmaxy()/2-p[2+c][1]);  
  line(p[3][0]+getmaxx()/2,getmaxy()/2-p[3][1],p[3+c][0]+getmaxx()/2,getmaxy()/2-p[3+c][1]);  
  line(p[4][0]+getmaxx()/2,getmaxy()/2-p[4][1],p[4+c][0]+getmaxx()/2,getmaxy()/2-p[4+c][1]);  
}  
void main()  
{  
  int gd=DETECT, gm=VGAHI;  
  initgraph(&gd,&gm,"");  
  char cho='1';  
  disp();  
  while (cho!='0')  
  {  
    cout<<"Enter choice ";  
    cin>>cho;  
    float ang;  
    switch (cho)  
    {  
      case '1':  
      float x,y,z;  
      cout<<"Enter x,y,z";  
      cin>>x>>y>>z;  
      scale(x,y,z);  
      break;  
      case '2':  
      cout<<"Enter x angle ";  
      cin>>ang;  
      ang*=M_PI/180;  
      rotx(ang);  
      break;  
      case '3':  
      cout<<"Enter y angle ";  
      cin>>ang;  
      ang*=M_PI/180;  
      roty(ang);  
      break;  
      case '4':  
      cout<<"Enter z angle ";  
      cin>>ang;  
      ang*=M_PI/180;  
      rotz(ang);  
      break;  
    }  
    cleardevice();  
    disp();  
  }  
  getch();  
}
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