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


 # define  f                 0.3
 # define  projection_angle   45


 void show_screen( );

 void apply_rotation_along_y_axis(constint,constint,constint,constint);
 void multiply_matrices(constfloat[4],constfloat[4][4],float[4]);

 void draw_circle(constint,constint,constint);
 void get_projected_point(int&,int&,int&);

 void Line(constint,constint,constint,constint);


 int main( )
    {
       int driver=VGA;
       int mode=VGAHI;

       initgraph(&driver,&mode,"..\\Bgi");

       show_screen( );

       int x=0;
       int y=250;
       int z=200;

      setcolor(15);
     draw_circle(x,y,z);

       setcolor(15);
       settextstyle(0,0,1);
     outtextxy(50,415,"*** Press any key to make a 3D solid object i.e. Tube.");

       getch( );

       for(int angle=0;angle<=360;angle++)
      apply_rotation_along_y_axis(x,y,z,angle);

       getch( );
       return 0;
    }


 /*************************************************************************///-------------------  apply_rotation_along_y_axis( )  ------------------///*************************************************************************/void apply_rotation_along_y_axis(constint x,constint y,
                        constint z,constint theta)
    {
       int _x=x;
       int _y=y;
       int _z=z;

       float angle=(theta*(M_PI/180));

       float matrix_a[4]={_x,_y,_z,1};

       float matrix_b[4][4]={
                   { cos(angle),0,-sin(angle),0 } ,
                   { 0,1,0,0 } ,
                   { sin(angle),0,cos(angle),0 } ,
                   { 0,0,0,1 }
                };

       float matrix_c[4]={0};

       multiply_matrices(matrix_a,matrix_b,matrix_c);

       _x=(int)(matrix_c[0]+0.5);
       _y=(int)(matrix_c[1]+0.5);
       _z=(int)(matrix_c[2]+0.5);

       draw_circle(_x,_y,_z);
    }

 /************************************************************************///----------------------  multiply_matrices( )  ------------------------///************************************************************************/void multiply_matrices(constfloat matrix_1[4],
                  constfloat matrix_2[4][4],float matrix_3[4])
    {
       for(int count_1=0;count_1<4;count_1++)
      {
         for(int count_2=0;count_2<4;count_2++)
        matrix_3[count_1]+=
               (matrix_1[count_2]*matrix_2[count_2][count_1]);
      }
    }

 /************************************************************************///--------------------------  draw_circle( )  -------------------------///************************************************************************/void draw_circle(constint x,constint y,constint z)
    {
       int _x=x;
       int _y=y;
       int _z=z;

       get_projected_point(_x,_y,_z);

       _x+=320;

       setcolor(15);
     circle(_x,_y,30);
    }

 /************************************************************************///---------------------  get_projected_point( )  -----------------------///************************************************************************/void get_projected_point(int& x,int& y,int& z)
    {
       float fcos0=(f*cos(projection_angle*(M_PI/180)));
       float fsin0=(f*sin(projection_angle*(M_PI/180)));

       float Par_v[4][4]={
                {1,0,0,0},
                {0,1,0,0},
                {fcos0,fsin0,0,0},
                {0,0,0,1}
             };

       float xy[4]={x,y,z,1};
       float new_xy[4]={0};

       multiply_matrices(xy,Par_v,new_xy);

       x=(int)(new_xy[0]+0.5);
       y=(int)(new_xy[1]+0.5);
       z=(int)(new_xy[2]+0.5);
    }

 /*************************************************************************///--------------------------  show_screen( )  ---------------------------///*************************************************************************/void show_screen( )
    {
       setfillstyle(1,1);
     bar(154,26,476,38);

       settextstyle(0,0,1);
     setcolor(15);
       outtextxy(5,5,"******************************************************************************");
       outtextxy(5,17,"*-**************************************************************************-*");
       outtextxy(5,29,"*----------------                                           -----------------*");
       outtextxy(5,41,"*-**************************************************************************-*");
       outtextxy(5,53,"*-**************************************************************************-*");

     setcolor(11);
       outtextxy(162,29,"Rotational Sweep Representation Method");

     setcolor(15);

       for(int count=0;count<=30;count++)
          outtextxy(5,(65+(count*12)),"*-*                                                                        *-*");

       outtextxy(5,438,"*-**************************************************************************-*");
       outtextxy(5,450,"*-------------------------                          -------------------------*");
       outtextxy(5,462,"******************************************************************************");

     setcolor(12);
       outtextxy(229,450,"Press any Key to exit.");
    }