/* To implement Bezier Curve */
#include<dos.h>
#include<graphics.h>
#include<conio.h>

int a[20],b[20],m,n=0,j,d;
float bx[5000],by[5000],u;
union REGS i,o;

initmouse()
{
	i.x.ax=0;
	int86(0x33,&i,&o);
	return(o.x.ax);
}

void showmouseptr()
{
	i.x.ax=1;
	int86(0x33,&i,&o);
}

void restrictmouseptr(int x1,int y1,int x2,int y2)
{
	i.x.ax=7;
	i.x.cx=x1;
	i.x.dx=x2;
	int86(0x33,&i,&o);
	i.x.ax=8;
	i.x.cx=y1;
	i.x.dx=y2;
	int86(0x33,&i,&o);
}

void getmousepos(int *button,int *x,int *y)
{
	i.x.ax=3;
	int86(0x33,&i,&o);
	*button=o.x.bx;
	*x=o.x.cx;
	*y=o.x.dx;
}

void hidemouseptr()
{
	i.x.ax=2;
	int86(0x33,&i,&o);
}

int compco()
{
	int k,coeff=1;
	for(k=d+1;k<=n;k++) coeff=coeff*k;
	for(k=2;k<=n-d;k++) coeff=coeff/k;
	return coeff;
}

float blenval()
{
	int k;
	float blend;
	blend=compco();
	for(k=1;k<=d;k++) blend=blend*u;
	for(k=1;k<=n-d;k++)	blend=blend*(1.0-u);
	return blend;
}

void bezier()
{
	float blend1;
	bx[j]=0;by[j]=0;
	for(d=0;d<=n;d++)
	{
		blend1=blenval();
		bx[j]+=a[d]*blend1;
		by[j]+=b[d]*blend1;
	}
}

void curve()
{
	for(j=0;j<m;j++) putpixel(bx[j],by[j],GREEN);
}

void drawi()
{
	for(j=0;j<=m;j++)
	{
		u=(float)j/m;
		bezier();
	}
	curve();
}

void main()
{
	int gd=DETECT,gm;
	int button,tx,ty;
	clrscr();
	m=4990;
	initgraph(&gd,&gm,"");
	cleardevice();
	showmouseptr();
	while(!kbhit())
	{

	   getmousepos(&button,&tx,&ty);
	   if((button & 1) == 1)
	   {
			hidemouseptr();
			setcolor(MAGENTA);
			a[n]=tx;
			b[n]=ty;
			//printf("%d %d\n",a[n],b[n]);
			putpixel(tx,ty,WHITE);
			circle(tx,ty,2);
			n++;
			delay(1000);
			showmouseptr();
		}
	}
	n--;
	drawi();
	getch();
}