// bezier collision
// by andre michelle
// am@andre-michelle.com
// http://www.extrajetzt.com


Bezier = function ( mc , p0 , p1 , p2 ) {

	// draw //

	mc.moveTo ( p0.x , p0.y );
	mc.curveTo ( p1.x , p1.y , p2.x , p2.y );

	// getPoints //

	var t = 0;
	var steps = 20;
	var num = 0;

	var pts = [];

	while ( t <= 1 ) {

		var t1 = 1 - t;
		var t1_2 = t1 * t1;
		var t2 = t * t;
		var tt12 = 2 * t * t1;

		var x = t1_2 * p0.x + tt12 * p1.x + t2 * p2.x;
		var y = t1_2 * p0.y + tt12 * p1.y + t2 * p2.y;

		pts.push ( { x: x, y: y } );

		t += 1/steps;

	}

	this.pts = pts;

}

BallWorld = function () {

	var ball = this.ball = scene.attachMovie ( "ball" , "ball" , 1 , { _x: 50, _y: -200, vy: 0 } );

	var br = ball._height/2;

	var bezier = this.bezier = new Bezier ( scene , { x: scene.n0._x, y: scene.n0._y } , { x: scene.n1._x, y: scene.n1._y } , { x: scene.n2._x, y: scene.n2._y } );

	var obj = this;

	ball.render = function () {

		var bezier = obj.bezier;

		var pts = bezier.pts;

		if ( Key.isDown ( Key.RIGHT ) ) ball.vx += .1;
		if ( Key.isDown ( Key.LEFT ) )  ball.vx -= .1;

		var bx = this._x;
		var by = this._y;

		var bvx = ball.vx;
		var bvy = ball.vy;

		bvy += .2;

		bx += bvx;
		by += bvy;

		for ( var p = 0 ; p < pts.length - 1 ; p++ ) {

			var p0 = pts[p];
			var p1 = pts[p+1];

			var p0x = p0.x, p0y = p0.y, p1x = p1.x, p1y = p1.y;

			// get Angle //

			var dx = p0x - p1x;
			var dy = p0y - p1y;

			var angle = Math.atan2( dy , dx );

			var sin = Math.sin ( angle );
			var cos = Math.cos ( angle );

			// rotate p1 ( need only 'x' ) //

			var p1rx = dy * sin + dx * cos + p0x;

			// rotate ball //

			var px = p0x - bx;
			var py = p0y - by;

			var brx = py * sin + px * cos + p0x;
			var bry = py * cos - px * sin + p0y;

			var cp = ( bx - p0x ) * ( p1y - p0y ) - ( by - p0y ) * ( p1x - p0x );

			if ( bry > p0y - br && brx > p0x && brx < p1rx && cp > 0 ) {

				// calc new Vector //

				var vx = bvy * sin + bvx * cos;
				var vy = bvy * cos - bvx * sin;

				vy *= -.8;
				vx *= .98;

				var sin = Math.sin ( -angle );
				var cos = Math.cos ( -angle );

				bvx = vy * sin + vx * cos;
				bvy = vy * cos - vx * sin;

				// calc new Position //

				bry = p0y - br;

				dx = p0x - brx;
				dy = p0y - bry;

				bx = dy * sin + dx * cos + p0x;
				by = dy * cos - dx * sin + p0y;

			}

		}

		if ( bx < br - 200 ) bx = br - 200, bvx = -bvx;
		if ( bx > 200 - br ) bx = 200 - br, bvx = -bvx;

		ball._x = bx;
		ball._y = by;

		ball.vx = bvx;
		ball.vy = bvy;

		if ( ball._y > 200 + br ) ball._y = -200, ball._x = 0, ball.vy = ball.vx = 0;

	}

	ball.onEnterFrame = function () { this.render () };

}

scene.lineStyle ( 0 , 0xffcc00 );

var XJ = new BallWorld ();

// dragging the anchor and control points //
// -------------------------------------- //

scene.n0.onPress = scene.n1.onPress = scene.n2.onPress = function () {

	delete XJ.ball.onEnterFrame;

	this.onEnterFrame = function () {

		this._x = scene._xmouse;
		this._y = scene._ymouse;

		scene.clear ();

		scene.lineStyle ( 0 , 0xffcc00 );

		XJ.bezier = new Bezier ( scene , { x: scene.n0._x, y: scene.n0._y } , { x: scene.n1._x, y: scene.n1._y } , { x: scene.n2._x, y: scene.n2._y } );

		XJ.ball.render ();

	}

	this.onRelease = this.onReleaseOutside = function () {

		XJ.ball.onEnterFrame = function () { XJ.ball.render () };

		delete this.onEnterFrame;

	}

}