function b2CreateBall(world, x, y, r, fixed) {
	if (typeof(fixed) == 'undefined') fixed = true;
	var ballSd = new b2CircleDef();
	if (!fixed) ballSd.density = 1;
	ballSd.radius = r;
	ballSd.restitution = ballBounce + (Math.random()*(ballBounceBias*10))/10;
	ballSd.friction = 0;
	var ballBd = new b2BodyDef();
	ballBd.AddShape(ballSd);
	ballBd.position.Set(x,y);
	return world.CreateBody(ballBd);
}

function b2CreateBox(world, x, y, width, height, fixed, r) {
	if (typeof(fixed) == 'undefined') fixed = true;
	if (typeof(r) == 'undefined') r = 0;
	var boxSd = new b2BoxDef();
	if (!fixed) boxSd.density = 1.0;
	boxSd.restitution = groundBounce;
	boxSd.friction = 0;
	boxSd.extents.Set(width, height);
	var boxBd = new b2BodyDef();
	boxBd.AddShape(boxSd);
	boxBd.position.Set(x,y);
	boxBd.rotation = r;
	return world.CreateBody(boxBd)
}