AndEngine Example(4):SpriteRemoveExample

目标：

1. 了解纹理 BitmapTextureAtlas

2. 纹理区域工场 BitmapTextureAtlasTextureRegionFactory

3. 锁 EngineLock

4. 移除精灵

package org.andengine.examples;import org.andengine.engine.Engine.EngineLock;import org.andengine.engine.camera.Camera;import org.andengine.engine.options.EngineOptions;import org.andengine.engine.options.ScreenOrientation;import org.andengine.engine.options.resolutionpolicy.RatioResolutionPolicy;import org.andengine.entity.scene.IOnSceneTouchListener;import org.andengine.entity.scene.Scene;import org.andengine.entity.scene.background.Background;import org.andengine.entity.sprite.Sprite;import org.andengine.entity.util.FPSLogger;import org.andengine.input.touch.TouchEvent;import org.andengine.opengl.texture.TextureOptions;import org.andengine.opengl.texture.atlas.bitmap.BitmapTextureAtlas;import org.andengine.opengl.texture.atlas.bitmap.BitmapTextureAtlasTextureRegionFactory;import org.andengine.opengl.texture.region.ITextureRegion;import org.andengine.ui.activity.SimpleBaseGameActivity;import android.widget.Toast;/** * (c) 2010 Nicolas Gramlich * (c) 2011 Zynga * * @author Nicolas Gramlich * @since 11:54:51 - 03.04.2010 */public class SpriteRemoveExample extends SimpleBaseGameActivity implements IOnSceneTouchListener {// ===========================================================// Constants// ===========================================================private static final int CAMERA_WIDTH = 720;private static final int CAMERA_HEIGHT = 480;// ===========================================================// Fields// ===========================================================private BitmapTextureAtlas mBitmapTextureAtlas;private ITextureRegion mFaceTextureRegion;private Sprite mFaceToRemove;// ===========================================================// Constructors// ===========================================================// ===========================================================// Getter & Setter// ===========================================================// ===========================================================// Methods for/from SuperClass/Interfaces// ===========================================================@Overridepublic EngineOptions onCreateEngineOptions() {Toast.makeText(this, "Touch the screen to safely remove the sprite.", Toast.LENGTH_LONG).show();final Camera camera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);return new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), camera);}@Overridepublic void onCreateResources() {BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");this.mBitmapTextureAtlas = new BitmapTextureAtlas(this.getTextureManager(), 32, 32, TextureOptions.BILINEAR);this.mFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mBitmapTextureAtlas, this, "face_box.png", 0, 0);this.mBitmapTextureAtlas.load();}@Overridepublic Scene onCreateScene() {this.mEngine.registerUpdateHandler(new FPSLogger());final Scene scene = new Scene();scene.setBackground(new Background(0.09804f, 0.6274f, 0.8784f));/* Calculate the coordinates for the face, so its centered on the camera. */final float centerX = (CAMERA_WIDTH - this.mFaceTextureRegion.getWidth()) / 2;final float centerY = (CAMERA_HEIGHT - this.mFaceTextureRegion.getHeight()) / 2;this.mFaceToRemove = new Sprite(centerX, centerY, this.mFaceTextureRegion, this.getVertexBufferObjectManager());scene.attachChild(this.mFaceToRemove);scene.setOnSceneTouchListener(this);return scene;}@Overridepublic boolean onSceneTouchEvent(final Scene pScene, final TouchEvent pSceneTouchEvent) {if(this.mFaceToRemove == null) {return false;}final EngineLock engineLock = this.mEngine.getEngineLock();engineLock.lock();/* Now it is save to remove the entity! */pScene.detachChild(this.mFaceToRemove);this.mFaceToRemove.dispose();this.mFaceToRemove = null;engineLock.unlock();return true;}// ===========================================================// Methods// ===========================================================// ===========================================================// Inner and Anonymous Classes// ===========================================================}

BitmapTextureAtlas 是一种Texture(纹理)

          BitmapTextureAtlas extends TextureAtlas

          TextureAtlas<T extends ITextureAtlasSource> extends Texture

(上一篇中使用的是 ITexture 对象，texture = new BitmapTexture(...) 它也是是extends自Texture)

BitmapTextureAtlasTextureRegionFactory 

设定AssetBasePath 路径，然后读取下面的"face_box.png" ，变成纹理，然后给mBitmapTextureAtlas，返回的则是一块纹理区域mFaceTextureRegion。

(这样就创建了 纹理 和 纹理区域)。

加锁： 关键区域需要加锁，例如移除精灵

final EngineLock engineLock = this.mEngine.getEngineLock();
engineLock.lock();

...

engineLock.unlock();

移除精灵：

1 先取消精灵与场景的绑定  detachChild

2 回收精灵dispose()

3 将对象置为空 = null

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扩展阅读：

场景 (Scenes)
AndEngine提供了一个场景类来让我们可以进行游戏场景的初始化。

Scenes拥有如下属性：

Scene mParentScene : 每个场景能够拥有可选的父场景

Scene mChildScene :每个场景能够拥有可选的子场景

SmartList<ITouchArea> mTouchAreas: (触碰区域)：场景能够知道接收了用户触摸的区域

IOnSceneTouchListener mOnSceneTouchListener: 场景被触摸的监听器

IOnAreaTouchListener mOnAreaTouchListener: 区域被触摸的监听器

RunnableHandler mRunnableHandler: 场景拥有的RunnableHandler.

IBackground mBackground : 每个场景都有背景，它是黑色实心的。

boolean mOnAreaTouchTraversalBackToFront: 是否需要响应触摸事件。

Layers of graphics can be attached to a Scene as children of the Scene.