AndEngine学习：PhysicsCollisionFiltering（有过滤器的碰撞检测）

　　这一篇很简单，应该先看完我写的另外一篇http://www.cnblogs.com/xiaobo68688/archive/2011/10/31/2230270.html后再读这一篇

// 声明：只是对AndEngine自带的例子做了修改和少许的改动，并不是完全原创，勿喷！
public class PhysicsCollisionFiltering extends BaseExample implements IAccelerometerListener, IOnSceneTouchListener
{
    // ===========================================================
    // Constants
    // ===========================================================

    private static final int CAMERA_WIDTH = 720;
    private static final int CAMERA_HEIGHT = 480;

    // 种类常量
    // 为了区分是否应该对碰撞作出反应
    public static final short CATEGORYBIT_WALL = 1;
    public static final short CATEGORYBIT_BOX = 2;
    public static final short CATEGORYBIT_CIRCLE = 4;

    // 这里记录了应该和什么碰撞
    public static final short MASKBITS_WALL = CATEGORYBIT_WALL + CATEGORYBIT_BOX + CATEGORYBIT_CIRCLE;
    public static final short MASKBITS_BOX = CATEGORYBIT_WALL + CATEGORYBIT_BOX; // Missing: CATEGORYBIT_CIRCLE
    public static final short MASKBITS_CIRCLE = CATEGORYBIT_WALL + CATEGORYBIT_CIRCLE; // Missing: CATEGORYBIT_BOX

    // 注册谁和谁应该碰撞的信息
    public static final FixtureDef WALL_FIXTURE_DEF = PhysicsFactory.createFixtureDef(0, 0.5f, 0.5f, false, CATEGORYBIT_WALL, MASKBITS_WALL, (short)0);
    public static final FixtureDef BOX_FIXTURE_DEF = PhysicsFactory.createFixtureDef(1, 0.5f, 0.5f, false, CATEGORYBIT_BOX, MASKBITS_BOX, (short)0);
    public static final FixtureDef CIRCLE_FIXTURE_DEF = PhysicsFactory.createFixtureDef(1, 0.5f, 0.5f, false, CATEGORYBIT_CIRCLE, MASKBITS_CIRCLE, (short)0);

    // ===========================================================
    // Fields
    // ===========================================================

    private BitmapTextureAtlas mBitmapTextureAtlas;

    private TiledTextureRegion mBoxFaceTextureRegion;
    private TiledTextureRegion mCircleFaceTextureRegion;

    private Scene mScene;

    private PhysicsWorld mPhysicsWorld;
    private int mFaceCount = 0;

    // ===========================================================
    // Constructors
    // ===========================================================

    // ===========================================================
    // Getter & Setter
    // ===========================================================

    // ===========================================================
    // Methods for/from SuperClass/Interfaces
    // ===========================================================

    public Engine onLoadEngine() {
        Toast.makeText(this, "Touch the screen to add objects.", Toast.LENGTH_LONG).show();
        Toast.makeText(this, "Boxes will only collide with boxes.\nCircles will only collide with circles.", Toast.LENGTH_LONG).show();
        final Camera camera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);
        final EngineOptions engineOptions = new EngineOptions(true, ScreenOrientation.LANDSCAPE, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), camera);
        engineOptions.getTouchOptions().setRunOnUpdateThread(true);
        return new Engine(engineOptions);
    }

    public void onLoadResources() {
        /* Textures. */
        this.mBitmapTextureAtlas = new BitmapTextureAtlas(64, 64, TextureOptions.BILINEAR_PREMULTIPLYALPHA);
        BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

        /* TextureRegions. */
        this.mBoxFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mBitmapTextureAtlas, this, "face_box_tiled.png", 0, 0, 2, 1); // 64x32
        this.mCircleFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mBitmapTextureAtlas, this, "face_circle_tiled.png", 0, 32, 2, 1); // 64x32
        this.mEngine.getTextureManager().loadTexture(this.mBitmapTextureAtlas);
    }

    public Scene onLoadScene() {
        this.mEngine.registerUpdateHandler(new FPSLogger());

        this.mScene = new Scene();
        this.mScene.setBackground(new ColorBackground(0, 0, 0));
        this.mScene.setOnSceneTouchListener(this);

        this.mPhysicsWorld = new PhysicsWorld(new Vector2(0, SensorManager.GRAVITY_EARTH), false);

        final Shape ground = new Rectangle(0, CAMERA_HEIGHT - 2, CAMERA_WIDTH, 2);
        final Shape roof = new Rectangle(0, 0, CAMERA_WIDTH, 2);
        final Shape left = new Rectangle(0, 0, 2, CAMERA_HEIGHT);
        final Shape right = new Rectangle(CAMERA_WIDTH - 2, 0, 2, CAMERA_HEIGHT);

        PhysicsFactory.createBoxBody(this.mPhysicsWorld, ground, BodyType.StaticBody, WALL_FIXTURE_DEF);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, roof, BodyType.StaticBody, WALL_FIXTURE_DEF);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, left, BodyType.StaticBody, WALL_FIXTURE_DEF);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, right, BodyType.StaticBody, WALL_FIXTURE_DEF);

        this.mScene.attachChild(ground);
        this.mScene.attachChild(roof);
        this.mScene.attachChild(left);
        this.mScene.attachChild(right);

        this.mScene.registerUpdateHandler(this.mPhysicsWorld);

        return this.mScene;
    }

    public void onLoadComplete() {

    }

    public boolean onSceneTouchEvent(final Scene pScene, final TouchEvent pSceneTouchEvent) {
        if(this.mPhysicsWorld != null) {
            if(pSceneTouchEvent.isActionDown()) {
                this.addFace(pSceneTouchEvent.getX(), pSceneTouchEvent.getY());
                return true;
            }
        }
        return false;
    }

    public void onAccelerometerChanged(final AccelerometerData pAccelerometerData) {
        final Vector2 gravity = Vector2Pool.obtain(pAccelerometerData.getX(), pAccelerometerData.getY());
        this.mPhysicsWorld.setGravity(gravity);
        Vector2Pool.recycle(gravity);
    }

    @Override
    public void onResumeGame() {
        super.onResumeGame();

        this.enableAccelerometerSensor(this);
    }

    @Override
    public void onPauseGame() {
        super.onPauseGame();

        this.disableAccelerometerSensor();
    }

    // ===========================================================
    // Methods
    // ===========================================================

    private void addFace(final float pX, final float pY) {
        this.mFaceCount++;
        Debug.d("Faces: " + this.mFaceCount);

        final AnimatedSprite face;
        final Body body;

        if(this.mFaceCount % 2 == 0) {
            face = new AnimatedSprite(pX, pY, this.mBoxFaceTextureRegion);
            body = PhysicsFactory.createBoxBody(this.mPhysicsWorld, face, BodyType.DynamicBody, BOX_FIXTURE_DEF);
        } else {
            face = new AnimatedSprite(pX, pY, this.mCircleFaceTextureRegion);
            body = PhysicsFactory.createCircleBody(this.mPhysicsWorld, face, BodyType.DynamicBody, CIRCLE_FIXTURE_DEF);
        }

        face.animate(200);

        this.mScene.attachChild(face);
        this.mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(face, body, true, true));
    }

    // ===========================================================
    // Inner and Anonymous Classes
    // ===========================================================
}