020402.fla

init();
onEnterFrame = main;
function init() {
	max = 10;
	grav = .6;
	bounce = -.5;
	damp = .98;
	b = new Array();
	for (i=0; i<max; i++) {
		attachMovie("ball", "b"+i, i);
		b[i] = _root["b"+i];
		b[i]._x = Math.random()*500+20;
		b[i]._y = Math.random()*360+20;
		b[i].vx = Math.random()*20-10;
		b[i].vy = Math.random()*20-10;
		b[i].m = Math.random()*20+10;
		b[i]._width = b[i]._height=b[i].m;
		b[i].rad=b[i]._width/2;
	}
}
function main() {
	for (i=0; i<b.length; i++) {
		bi = b[i];
		if (bi._x<220) {
			bi.vx += 1/bi.m;
		} else if (bi._x>320) {
			bi.vx -= 1/bi.m;
		} else {
			bi.vy -= bi._y*.06/bi.m;
			bi.vx -= (270-bi._x)*.03/bi.m;
		}
		bi.vy += grav;
		bi.vx *= damp;
		bi.vy *= damp;
		bi._x += bi.vx;
		bi._y += bi.vy;
		if (bi._x>520-bi.rad) {
			bi._x = 520-bi.rad;
			bi.vx *= bounce;
		}
		if (bi._x<20+bi.rad) {
			bi._x = 20+bi.rad;
			bi.vx *= bounce;
		}
		if (bi._y>370-bi.rad) {
			bi._y = 370-bi.rad;
			bi.vy *= bounce;
		}
	}
	for (i=0; i<b.length-1; i++) {
		for (j=i+1; j<b.length; j++) {
			checkColl(b[i], b[j]);
		}
	}
}
function checkColl(b1, b2) {
	var dx = b2._x-b1._x;
	var dy = b2._y-b1._y;
	var dist = Math.sqrt(dx*dx+dy*dy);
	if (dist<b1.rad+b2.rad) {
		var angle = Math.atan2(dy, dx);
		cosa = Math.cos(angle);
		sina = Math.sin(angle);
		vx1p = cosa*b1.vx+sina*b1.vy;
		vy1p = cosa*b1.vy-sina*b1.vx;
		vx2p = cosa*b2.vx+sina*b2.vy;
		vy2p = cosa*b2.vy-sina*b2.vx;
		P = vx1p*b1.m+vx2p*b2.m;
		V = vx1p-vx2p;
		vx1p = (P-b2.m*V)/(b1.m+b2.m);
		vx2p = V+vx1p;
		b1.vx = cosa*vx1p-sina*vy1p;
		b1.vy = cosa*vy1p+sina*vx1p;
		b2.vx = cosa*vx2p-sina*vy2p;
		b2.vy = cosa*vy2p+sina*vx2p;
		diff = ((b1.rad+b2.rad)-dist)/2;
		cosd=cosa*diff;
		sind=sina*diff;
		b1._x -= cosd;
		b1._y -= sind;
		b2._x += cosd;
		b2._y += sind;
	}
}