#include<stdio.h>
#include<graphics.h>
#include<bios.h>
#include<stdlib.h>
typedef double CoArr[4];

char buf[20];

void BezierCurve(CoArr x, CoArr y, int n, int value)
{
	int i;
	double delta=1.0/n;
	double t=0, T;
	int a,b;

	setcolor(8);

	for(i=0;i<4;i++)
		line(x[i],y[i],x[(i+1)%4],y[(i+1)%4]);

	for(i=0;i<n;i++)
	{
		t+=delta;
		T=1-t;
		a=x[0]*T*T*T+3*t*T*T*x[1]+3*t*t*T*x[2]+t*t*t*x[3];
		b=y[0]*T*T*T+3*t*T*T*y[1]+3*t*t*T*y[2]+t*t*t*y[3];
		putpixel(a,b,value);
	}
}

void main()
{
	CoArr x,y;
	int gdriver = DETECT, gmode;
	int val;
	char *str;
	double  *movex;
	double *movey;
	int key;
	int flag = 3;

  x[0]=100; y[0]=100;
  x[3]=400; y[3]=100;
	x[1]=200; y[1]=350;
	x[2]=300; y[2]=150;

	initgraph(&gdriver,&gmode,"e:\\cpp\\tc\\bgi");

	BezierCurve(x,y,1000,15);
	movex=&x[1];
	movey=&y[1];

	while((key=bioskey(0))!=283)
	{
		//BezierCurve(x,y,1000,0);
		cleardevice();
		switch(key)
		{
		  case 3849:
			if(flag == 0)
			{
				flag = 1;
				movex=&x[0]; movey=&y[0];
			}
			else if(flag == 1)
			{
				flag = 2;
				movex=&x[1]; movey=&y[1];
			}
			else if(flag == 2)
			{
				flag = 3;
				movex=&x[2]; movey=&y[2];
			}
			else if(flag == 3)
			{
				flag = 0;
				movex=&x[3]; movey=&y[3];
			}
			break;

		 case 18432:
			*movey-=5; break;
		 case 20480:
			*movey+=5; break;
		 case 19200:
			*movex-=5; break;
		 case 19712:
			*movex+=5; break;
		 }
		 if(flag ==0)
		 {
			setcolor(4);
			circle(x[3],y[3],3);
		 }
		 else if(flag == 1)
		 {
			setcolor(4);
			circle(x[0],y[0],3);
		 }
		 else if(flag == 2)
		 {
			setcolor(YELLOW);
			circle(x[1],y[1],3);
		 }
		 else if(flag == 3)
		 {
			setcolor(YELLOW);
			circle(x[2],y[2],3);
		 }
		 val = (int)x[1];
		 itoa(val,str,10);
		 setcolor(4);
		 outtextxy(50,50,str);

		 val = (int)y[1];
		 itoa(val,str,10);
		 setcolor(4);
		 outtextxy(80,50,str);

		 val = (int)x[2];
		 itoa(val,str,10);
		 setcolor(4);
		 outtextxy(50,80,str);

		 val = (int)y[2];
		 itoa(val,str,10);
		 setcolor(4);
		 outtextxy(80,80,str);

		 BezierCurve(x,y,1000,15);
	}
//	getch();
}