#include "graphics.h"
#include <stdio.h>
#define PONT 4

void curvedraw(pont2d G[PONT], float M[4][4], int s)
{
    pont2d C[4]={0},P;
    int i,j,tipus=0;
    float a=0,b=1;

    if( M[2][2] == 1 )
    {
      tipus = 1; // 1: Hermit
      a = -1;
      b = 2;
    }

    float t=a,eps=(b-a)/s;

    for(i=0; i<4; i++)
    {
        for(j=0; j<4; j++)
        {
                 C[i].x += G[j].x * M[j][i];
                 C[i].y += G[j].y * M[j][i];
        }
    }

   if( tipus == 0 )
     moveto(
       (int) (C[0].x*t*t*t + C[1].x*t*t + C[2].x*t + C[3].x),
       (int) (C[0].y*t*t*t + C[1].y*t*t + C[2].y*t + C[3].y)
     );
   else
     moveto( (int)G[0].x, (int)G[0].y );

    for(t=a; t<=b; t+=eps)
    {
             P.x = (int) C[0].x*t*t*t + C[1].x*t*t + C[2].x*t + C[3].x;
             P.y = (int) C[0].y*t*t*t + C[1].y*t*t + C[2].y*t + C[3].y;
             lineto( (int)P.x, (int)P.y );
    }

    moveto( (int)G[0].x, (int)G[0].y );
    for(i=1; i<4; i++)
      lineto( (int)G[i].x, (int)G[i].y );
}

int main()
{
    int gd,gm,ap,i,j,page=0;
    pont2d pontok[PONT], G[4];

    float H[4][4] = 
    {
           {-1.0/6,  1.0/2, -1.0/3, 0},
           { 1.0/2, -1,     -1.0/2, 1},
           {-1.0/2,  1.0/2,  1,     0},
           { 1.0/6,  0,     -1.0/6, 0}
    };

    float B[4][4] = 
    {
           {-1.0/6,  3.0/6, -3.0/6, 1.0/6},
           { 3.0/6, -6.0/6,  0.0,   4.0/6},
           {-3.0/6,  3.0/6,  3.0/6, 1.0/6},
           { 1.0/6,  0.0,    0.0,   0.0}
    };

    gd = VGA;
    gm = VGAMAX;
    initgraph(&gd,&gm,"");

    for(i=0, j=50; i<PONT; i++, j+=50)
    pontok[i].x = pontok[i].y = j;

    while(42)
    {
        setactivepage(page);
        cleardevice();

        if(!balgomb)
          ap = getactivepoint((pont2d*)pontok,PONT,3);

        if(ap>=0 && balgomb)
        {
          pontok[ap].x = egerx;
          pontok[ap].y = egery;
        }

        for(i=0; i<PONT-3; i++)
        {
          G[0]=pontok[i];
          G[1]=pontok[i+1];
          G[2]=pontok[i+2];
          G[3]=pontok[i+3];
          curvedraw(G, B, 100);
        }

        for(i=0; i<PONT; i++)
          fillellipse( (int)pontok[i].x, (int)pontok[i].y, 3, 3 );

        setvisualpage(page);
        page = 1-page;

        if (kbhit())
          break;
    }

    closegraph();
    return 0;
}