flash 游戏设计笔记：切割位图技术
今天探讨一下这个关于切割位图的技术，关于这个做法，其实很简单。我将其定义为两种常见的切割技术，第一种为一维切割，第二种为二维切割。将不同切割出来的图片保存在数组当中。 
一维切割：如contain[图片编码]
二维切割：如contain[方向][步数]
应用在我们做一张RPG图的时候会应用到这种技术。从这张网上下载的图片可以看出，这种图有8个方向，属于8方图。
从这张图片我们可以看出，它排列就像一个二维数组阵列。 我们创建一个数组二维数组将这些图片储存起来，变成一个二维数组。
在As3里面做法，其中一种思路就是把这张图片进行复制，按比例，宽度和大小进行存取。最后，可以看到数组变成了：
如contain[方向][步数]
假设 第一张图，那么contain[0][0] 就代表第一行，第一列的图片，同理contain[1][0]就是第二行，第一列的图片。这样做一个目的是把数组的第一个数设计为方向，而第二个数设计为步数。
下面是切割二维的做法封装成一个类：
package {/* 切割位图类，返回一个二维数组*/import flash.display.Sprite;import flash.display.Bitmap;import flash.display.BitmapData;import flash.geom.*;public class BitmapSplice extends Sprite{public var contain:Sprite=new Sprite();//容器//public var direction:uint;//方向private var titleWidth:uint;//图片元件分取的宽 private var titleHeight:uint;//图片元件分取的高 private var bitmapdata:BitmapData;//位图源图像private var Step:Array=new Array();//存取步数数组public function BitmapSplice(bitmapdata:BitmapData,titleWidth:uint,titleHeight:uint){this.bitmapdata=bitmapdata;this.titleWidth=titleWidth;this.titleHeight=titleHeight;}//进行切割public function Splice():Array{var iWidth:int=this.bitmapdata.width /this.titleWidth;var iHeight:int=this.bitmapdata.height /this.titleHeight;for (var i:uint=0; i < titleHeight; i++){var array:Array=new Array();for (var j:uint=0; j < titleWidth; j++){var tempBMP:BitmapData=new BitmapData(iWidth,iHeight,true,0x00000000);tempBMP.copyPixels(bitmapdata,new Rectangle(j * iWidth,i * iHeight,iWidth,iHeight),new Point(0,0));array.push(tempBMP);}this.Step.push(array);}bitmapdata.dispose(); return this.Step;}}}package {import flash.display.Stage;import flash.events.*;import flash.display.Sprite;import flash.display.Bitmap;import flash.display.BitmapData;import com.hero.ImageManager.*;public class Control extends EventDispatcher{ private var sence:Sprite;private var Images:Array;private var direction:uint=1;//方向private var step:uint=1;//步数private var vx:int=0;private var vy:int=0;private var speed:int=10;private var n_step:uint;private var player:Sprite=new Sprite();public function Control(stage:Stage,sence:Sprite,Images:Array,n_step:uint){KEY.init(stage);//键盘初始化 this.sence=sence;//场景this.Images=Images;this.n_step=n_step;this.sence.addChild(player);player.x=250;player.y=150;stage.addEventListener(Event.ENTER_FRAME,Run);//使用stage才可以进行监听}private function Run(event:Event):void{ while (player.numChildren>0){player.removeChildAt(0);}player.addChild(new Bitmap(Images[direction][step]));keyboardListener();}private function keyboardListener():void{ if (KEY.isDown(KEYID.VK_UP) && KEY.isDown(KEYID.VK_LEFT)){goLeftAndTop();}else if (KEY.isDown(KEYID.VK_UP) && KEY.isDown(KEYID.VK_RIGHT)){goRightAndTop();trace("d");}else if (KEY.isDown(KEYID.VK_DOWN) && KEY.isDown(KEYID.VK_LEFT)){goLeftAndDown();}else if (KEY.isDown(KEYID.VK_DOWN) && KEY.isDown(KEYID.VK_RIGHT)){goRightAndDown();}else if (KEY.isDown(KEYID.VK_UP)){goUP();}else if (KEY.isDown(KEYID.VK_DOWN)){goDown();}else if (KEY.isDown(KEYID.VK_LEFT)){goLeft();}else if (KEY.isDown(KEYID.VK_RIGHT)){goRight();}else if (!KEY.isDown(KEYID.VK_LEFT) && !KEY.isDown(KEYID.VK_UP) && !KEY.isDown(KEYID.VK_RIGHT) && !KEY.isDown(KEYID.VK_DOWN)){stand();}}private function goLeftAndTop():void{go(-1,-1,3);}private function goRightAndTop():void{go(1,-1,6);}private function goLeftAndDown():void{go(-1,1,4);}private function goRightAndDown():void{go(1,1,7);}private function goUP():void{go(0,-1,0);}public function goDown():void{go(0,1,1);}private function goLeft():void{go(-1,0,2);}private function goRight():void{go(1,0,5);}private function stand():void{vx=0;vy=0;step=0;}private function go(_xv:int,_yv:int,direction:uint):void{this.direction=direction;vx = _xv*speed;vy = _yv*speed;step++;if (step>n_step-1){step=1;}player.x+=vx;player.y+=vy;sence.x -= vx;sence.y -= vy;}}}package {import flash.display.Sprite;import flash.display.DisplayObject;import flash.display.BitmapData;import flash.display.Bitmap;import flash.events.*;import com.hero.ImageManager.*;public class Test extends Sprite{private var bit:BitmapSplice;private var Images:Array;private var sence:Sprite=new Sprite();//场景类，设计为容器private var mycontrol:Control;public function Test(){ sence.addChildAt(new Bitmap(new Sence1(0,0)),0);bit=new BitmapSplice(new player(0,0),9,8);//player 类为库链接的位图Images=bit.Splice();//分割二维数组mycontrol=new Control(stage,sence,Images,9);addChild(sence);//位图容器初始化addEventListener(Event.ENTER_FRAME,Run);}private function Run(event:Event):void{}}}KEY类用于键盘监控时候使用package com.hero.ImageManager{/*键盘按键判断类.使用时先初始化要监听的对象.再判断哪个键被按下了.KEY.init(stage);KEY.isDown(40);返回true或false*/import flash.events.Event;import flash.events.KeyboardEvent;import flash.display.DisplayObject;public class KEY { private static var keyObj:KEY = null; private static var keys:Object; public static function init(_stage:DisplayObject):void { if (keyObj == null) { keys = {}; _stage.addEventListener(KeyboardEvent.KEY_DOWN, KEY.keyDownHandler); _stage.addEventListener(KeyboardEvent.KEY_UP, KEY.keyUpHandler); } } public static function isDown( keyCode:uint ):Boolean { return keys[keyCode]; } private static function keyDownHandler( e:KeyboardEvent ):void { keys[e.keyCode] = true;trace( keys[e.keyCode]); } private static function keyUpHandler( e:KeyboardEvent ):void { delete keys[e.keyCode]; } }}package com.hero.ImageManager{public final class KEYID{public static const VK_LEFT:uint = 37;public static const VK_UP:uint = 38;public static const VK_RIGHT:uint = 39;public static const VK_DOWN:uint = 40;}}