// Hellow Snow!!!
// forked from Saqoosha's Snow
package {
	import flash.display.Bitmap;
	import flash.display.BitmapData;
	import flash.display.BlendMode;
	import flash.display.PixelSnapping;
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.filters.BlurFilter;
	import flash.geom.Matrix;
	import flash.geom.Point;
	import flash.geom.Rectangle;
	import flash.text.TextField;
	import flash.text.TextFieldAutoSize;
	import flash.text.TextFormat;

[SWF(width=465, height=465, backgroundColor=0x0, frameRate=120)]

public class Snow extends Sprite {
		private static const WIND_X:Number = 40;
		private static const WIND_Y:Number = -15;
		private static const GRAVITY:Number = 10;
		private static const START_Y:Number = 200;
		
		private var _canvas:BitmapData;
		private var _textBmp:BitmapData;
		private var _glow:BitmapData;
		private var _glowMtx:Matrix;
		private var _snow:Array;
		private var _snow_prepare:Array;
		private var _text:TextField;
		private var _log:TextField;
		
		public function Snow() {
			stage.scaleMode = "noScale";

_text = new TextField();
			_text.defaultTextFormat = new TextFormat('Verdana', 48, 0xffffff, true); 
			_text.text = "Hello Snow!!!";
			_text.autoSize = "left";
			_textBmp = new BitmapData(465, 465, false, 0x000000);
			this._canvas = new BitmapData(465, 465, false, 0x000000);
			//this.addChild(new Bitmap(_textBmp));
			this.addChild(new Bitmap(this._canvas));

this._snow = [];
			this._snow_prepare = [];

this._glow = new BitmapData(465 / 4, 465 / 4, false, 0x0); // キラキラを描く用のん。カンバスの 4 分の 1 のサイズ
			var bm:Bitmap = this.addChild(new Bitmap(this._glow, PixelSnapping.NEVER, true)) as Bitmap; // smoothing を true にして配置
			bm.scaleX = bm.scaleY = 4; // 4 倍にする。
			bm.blendMode = BlendMode.ADD; // 加算モードで合成
			this._glowMtx = new Matrix(0.25, 0, 0, 0.25);

// init _snow_prepare

this.addEventListener(Event.ENTER_FRAME, function(event:Event):void{
				for(var i:int = 0; i < 3; i++){
					if(_snow_prepare.length){
						var index:int = Math.random() * Math.min(30, _snow_prepare.length);
						var particle:SnowParticle = _snow_prepare[index];
						_snow_prepare.splice(index, 1);
						_textBmp.setPixel(particle.x, particle.y, 0x000000);
						_snow.push(particle);
					}
				}
				if(_snow_prepare.length || _snow.length){
					update(null);
				}else{
					init();
				}
			});

init();
		}

public function init():void{
			var mtx:Matrix = new Matrix();
			mtx.ty = START_Y;
			_textBmp.draw(_text, mtx);

var rect:Rectangle = _textBmp.getColorBoundsRect(0, 0, false);
			for(var x:int = rect.left; x <= rect.right; x++){
				for(var y:int = rect.top; y <= rect.bottom; y++){
					var col:uint = _textBmp.getPixel(x, y);
					if(col != 0x000000){
						_snow_prepare.push(new SnowParticle(x, y, col, Math.random(), -Math.random()));
					}
				}
			}
			_snow_prepare.sort(function(a:SnowParticle, b:SnowParticle):int{
				var _a:int = a.x + a.y * 3;
				var _b:int = b.x + b.y * 3;
				return _a > _b ? 1 : _a == _b ? 0 : -1;
			});
		}

// 雪を動かすよーー
		public function update(e:Event):void {
			this._canvas.lock(); // いっぱい setPixel するときは必ず lock しよう
			this._canvas.fillRect(this._canvas.rect, 0x0); // カンバスをクリア
			this._canvas.copyPixels(_textBmp, _textBmp.rect, new Point(0, 0));
			var n:int = this._snow.length;
			var d:Number = 1.0;
			var wind_x:Number = (Math.random() > .4 ? WIND_X : 0) / 1000;
			var wind_y:Number = (GRAVITY + (Math.random() > .6 ? WIND_Y : WIND_Y / 2)) / 1000;
			while (n--) {
				var p:SnowParticle = this._snow[n];
				p.vx += wind_x * p.s;
				p.vy += wind_y * p.s;
				p.vx *= 0.99; // 空気抵抗
				p.vy *= 0.99; // y 方向にも
				p.x += p.vx; // 動かす
				p.y += p.vy;
				this._canvas.setPixel(p.x, p.y, p.c); // 雪 1 粒描く
				if (p.y < 0 || p.y > this.stage.stageHeight || p.x > this.stage.stageWidth) { // もし画面外にでちゃったら
					this._snow.splice(n, 1); // とりのぞく
				}
			}
			this._canvas.unlock(); // lock したやつは必ず unlock
			this._glow.draw(this._canvas, this._glowMtx); // キラキラを描く
		}
	}
}

class SnowParticle {
	
	public var x:Number;
	public var y:Number;
	public var vx:Number;
	public var vy:Number;
	public var s:Number;
	public var c:int;
	
	public function SnowParticle(x:Number, y:Number, color:uint, vx:Number, vy:Number) {
		this.x = x;
		this.y = y;
		this.vx = vx;
		this.vy = vy;
		this.s = 1;
		this.c = color;
	}
}