flex游戏引擎(PushBotton)-执行流
PushButton Engine不会主动执行主循环从而控制你的游戏，你必须要亲自启动它
Engine Startup
如果你使用PushButton Engine MXML tags，在程序启动时尽可能早地处理，层相关的tags在应用程序事件结束后处理，资源 相关的tags在被flex加载时立刻被处理 - usually in the first few frames.
???? 为了管理这些tag，ResourceManager, LevelManager, and other managers也许被初始化和创建
??? 如果你手动启动游戏，直接调用管理者，不使用标签。
?? ProcessManager管理着主循环和回调函数，并允许你设置回调对象的相关优先级
?? Frame Callbacks框架回调在IAnimatedObject接口中发生，简单执行IAnimatedObject interface，调用ProcessManager.instance.addAnimatedObject(this)，如：
?? // Example of a component that receives per-frame callbacks.
?? public class DemoAnimatedComponent extends EntityComponent implements IAnimatedObject
?? {
????? public function onFrame(elapsed:Number):void
????? {
???????? trace("Frame happened, and " + elapsed + "ms passed since last time.");
????? }
?????
????? protected override function onAdd():void
????? {
???????? ProcessManager.instance.addAnimatedObject(this);
????? }
?????
????? protected override function onRemove():void
????? {
???????? ProcessManager.instance.removeAnimatedObject(this);
????? }
?? }
PBLabs.Engine.Components.AnimatedComponent帮你自动注册和注销活跃对象，并可以设置优先级
Ticks
Ticks确保在固定间隔发生,ProcessManager负责产生Ticks，相当一个计时器，在onTick回调时，执行自己的代码。
?? // Example of a component which receives tick callbacks.
?? public class DemoTickedComponent extends EntityComponent implements ITickedObject
?? {
????? public function onTick(tickRate:Number):void
????? {
???????? trace("A tick happened!");
????? }
?????
????? protected override function onAdd():void
????? {
???????? ProcessManager.instance.addTickedObject(this);
????? }
?????
????? protected override function onRemove():void
????? {
???????? ProcessManager.instance.removeTickedObject(this);
????? }
?? }
TickedComponent基类简单创建一个产生ticks的组件
ProcessManager,在第个frame(框架)的开始处(the ENTER_FRAME事件),做以下工作:
ProcessManager产生：IAnimatedObject回调、tick回调ITickedObject onTick、待定事件
Process IAnimatedObject callbacks.
Process any pending ticks by calling ITickedObject onTick zero or more times.
Process any pending events.
