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


 # define Xc -0.3
 # define Yc  0.3
 # define Zc -1.0


 void show_screen( );

 void draw_3d_polygon(int [5][3],int [8][2],int [5][5]);
 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 vertices[5][3]={
                {245,325,75},      //  base front left
                {395,325,75},      //  base front right
                {395,325,-75},     //  base back right
                {245,325,-75},     //  base back left
                {320,125,0}        //  top
              };

       int edges[8][2]={
             // first is starting point vertex number// second is ending point vertex number
             {0,3} , {3,2} , {2,1} , {1,0} , {0,4} ,
             {3,4} , {2,4} , {1,4}
               };

       int surfaces[5][5]={
                 // First entry is number of edges// Rest entries are edge numbers
                 {4,0,1,2,3}, {3,0,4,5} , {3,1,5,6} ,
                 {3,2,6,7} , {3,3,4,7}
              };

       for(int i=0;i<5;i++)
      get_projected_point(vertices[i][0],vertices[i][1],vertices[i][2]);

       setcolor(15);
     draw_3d_polygon(vertices,edges,surfaces);

       settextstyle(2,0,4);
     setcolor(11);
       outtextxy(300,355,"S1");
       outtextxy(260,270,"S2");
       outtextxy(310,250,"S3");
       outtextxy(370,280,"S4");
       outtextxy(310,317,"S5");

     setcolor(10);
       outtextxy(255,315,"E1");
       outtextxy(320,291,"E2");
       outtextxy(403,315,"E3");
       outtextxy(310,337,"E4");
       outtextxy(250,250,"E5");
       outtextxy(288,240,"E6");
       outtextxy(390,240,"E7");
       outtextxy(356,260,"E8");

     setcolor(14);
       outtextxy(212,344,"V1");
       outtextxy(255,293,"V2");
       outtextxy(420,293,"V3");
       outtextxy(370,350,"V4");
       outtextxy(320,115,"V5");

       getch( );
       closegraph( );
       return 0;
    }

 /************************************************************************///-------------------------  draw_3d_polygon( )  -----------------------///************************************************************************/void draw_3d_polygon(int vertices[5][3],int edges[8][2],int surfaces[5][5])
    {
       for(int i=0;i<5;i++)
      {
         for(int j=1;j<=surfaces[i][0];j++)
        {
           int x_1=vertices[edges[surfaces[i][j]][0]][0];
           int y_1=vertices[edges[surfaces[i][j]][0]][1];
           int x_2=vertices[edges[surfaces[i][j]][1]][0];
           int y_2=vertices[edges[surfaces[i][j]][1]][1];

           Line(x_1,y_1,x_2,y_2);
        }
      }
    }

 /************************************************************************///---------------------  get_projected_point( )  -----------------------///************************************************************************/void get_projected_point(int& x,int& y,int& z)
    {
       float projection_matrix[4][4]={
                      { -Zc,0,0,0 },
                      { 0,-Zc,0,0 },
                      { Xc,Yc,0,1 },
                      { 0,0,0,-Zc }
                   };

       float matrix3d[4]={x,y,z,1};
       float matrix2d[4]={0,0,0,0};

       for(int count_1=0;count_1<4;count_1++)
      {
         for(int count_2=0;count_2<4;count_2++)
        matrix2d[count_1]+=
               (matrix3d[count_2]*projection_matrix[count_2][count_1]);
      }

       x=(int)(matrix2d[0]+0.5);
       y=(int)(matrix2d[1]+0.5);
       z=(int)(matrix2d[2]+0.5);
    }

 /*************************************************************************///--------------------------  Line( )  ------------------------///*************************************************************************/void Line(constint x_1,constint y_1,constint x_2,constint y_2)
    {
       int color=getcolor( );

       int x1=x_1;
       int y1=y_1;

       int x2=x_2;
       int y2=y_2;

       if(x_1>x_2)
      {
         x1=x_2;
         y1=y_2;

         x2=x_1;
         y2=y_1;
      }

       int dx=abs(x2-x1);
       int dy=abs(y2-y1);
       int inc_dec=((y2>=y1)?1:-1);

       if(dx>dy)
      {
         int two_dy=(2*dy);
         int two_dy_dx=(2*(dy-dx));
         int p=((2*dy)-dx);

         int x=x1;
         int y=y1;

         putpixel(x,y,color);

         while(x<x2)
        {
           x++;

           if(p<0)
              p+=two_dy;

           else
              {
             y+=inc_dec;
             p+=two_dy_dx;
              }

           putpixel(x,y,color);
        }
      }

       else
      {
         int two_dx=(2*dx);
         int two_dx_dy=(2*(dx-dy));
         int p=((2*dx)-dy);

         int x=x1;
         int y=y1;

         putpixel(x,y,color);

         while(y!=y2)
        {
           y+=inc_dec;

           if(p<0)
              p+=two_dx;

           else
              {
             x++;
             p+=two_dx_dy;
              }

           putpixel(x,y,color);
        }
      }
    }

 /*************************************************************************///--------------------------  show_screen( )  ---------------------------///*************************************************************************/void show_screen( )
    {
       setfillstyle(1,1);
     bar(205,26,438,38);

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

     setcolor(11);
       outtextxy(214,29,"Polygon-Mesh Representation");

     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(227,450,"  Press any key to exit ");
    }