#include <graphics.h>
#include <conio.h>
#include <time.h>

#define N 11
#define width 640
#define length 480
#define R 20

void change(int *rx, int *ry, int *x, int *y);
void wcircle(int *x, int *y);

void main()
{
	initgraph(640,480);
	int x[N], y[N];
	int rx[N], ry[N];
	int i;
	srand((unsigned)time(NULL));
	for(i = 0;i < N;i++)
	{
		x[i] = rand()%320;
		y[i] = rand()%240;
		rx[i] = rand()%2 + 1;
		ry[i] = rand()%2 + 1;	
	}
	while(1)
	{		
		cleardevice();
		BeginBatchDraw();
		for(i = 0;i < N;i++)
		{
			wcircle(&x[i], &y[i]);
			change(&rx[i], &ry[i], &x[i], &y[i]);
		}
		FlushBatchDraw();			
		Sleep(10);			
	}
	getch();
	closegraph();
}


void wcircle(int *x, int *y)
{
	setfillcolor(RED);
	fillcircle(*x, *y, R);
}


void change(int *rx, int *ry, int *x, int *y)
{
	if((*x+20) > width || (*x-20) < 0)
	{
		*rx *= -1;
	}
	if((*y+20) > length || (*y-20) < 0)
	{
		*ry *= -1;
	}	
	*x += *rx;
	*y += *ry;	
}