android游戏引擎andengine学习系列三：绘制游戏虚拟摇杆

@Override
	public Engine onLoadEngine() {
		this.mCamera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);
		final Engine engine = new Engine(new EngineOptions(true, ScreenOrientation.LANDSCAPE, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), this.mCamera));

		try {		//因为有两个摇杆，需要两个手指同时进行，所以这里要注册多点触控
			if(MultiTouch.isSupported(this)) {
				engine.setTouchController(new MultiTouchController());
				if(MultiTouch.isSupportedDistinct(this)) {
					Toast.makeText(this, "MultiTouch detected --> Both controls will work properly!", Toast.LENGTH_LONG).show();
				} else {
					this.mPlaceOnScreenControlsAtDifferentVerticalLocations = true;
					Toast.makeText(this, "MultiTouch detected, but your device has problems distinguishing between fingers.\n\nControls are placed at different vertical locations.", Toast.LENGTH_LONG).show();
				}
			} else {
				Toast.makeText(this, "Sorry your device does NOT support MultiTouch!\n\n(Falling back to SingleTouch.)\n\nControls are placed at different vertical locations.", Toast.LENGTH_LONG).show();
			}
		} catch (final MultiTouchException e) {
			Toast.makeText(this, "Sorry your Android Version does NOT support MultiTouch!\n\n(Falling back to SingleTouch.)\n\nControls are placed at different vertical locations.", Toast.LENGTH_LONG).show();
		}

		return engine;
	}

public void onLoadResources() {

		this.mTexture = new Texture(32, 32, TextureOptions.BILINEAR_PREMULTIPLYALPHA);
		this.mFaceTextureRegion = TextureRegionFactory.createFromAsset(this.mTexture, this, "face_box.png", 0, 0);

		this.mOnScreenControlTexture = new Texture(256, 128, TextureOptions.BILINEAR_PREMULTIPLYALPHA);
		this.mOnScreenControlBaseTextureRegion = TextureRegionFactory.createFromAsset(this.mOnScreenControlTexture, this, "onscreen_control_base.png", 0, 0);	//这里是加载摇杆的地盘的纹理图片 
		this.mOnScreenControlKnobTextureRegion = TextureRegionFactory.createFromAsset(this.mOnScreenControlTexture, this, "onscreen_control_knob.png", 128, 0);	//这里是加载摇杆的纹理图片

		this.mEngine.getTextureManager().loadTextures(this.mTexture, this.mOnScreenControlTexture);
	}

public Scene onLoadScene() {
this.mEngine.registerUpdateHandler(new FPSLogger());
final Scene scene = new Scene(1);
scene.setBackground(new ColorBackground(0.09804f, 0.6274f, 0.8784f));
final int centerX = (CAMERA_WIDTH - this.mFaceTextureRegion.getWidth()) / 2;
final int centerY = (CAMERA_HEIGHT - this.mFaceTextureRegion.getHeight()) / 2;
final Sprite face = new Sprite(centerX, centerY, this.mFaceTextureRegion);
scene.getTopLayer().addEntity(face);
//-------------------------------------------以下为左摇杆的实现----------------------------------------------------------------------																final int x1 = 0;													//y坐标为屏幕的高度减去摇杆底盘的高度，注意屏幕在前面已经被强制横屏
final int y1 = CAMERA_HEIGHT - this.mOnScreenControlBaseTextureRegion.getHeight();																				//AnalogOnScreenControl构造方法中：第一第二参数是该摇杆的坐标，第三个参数为上面定义camera，第四第五个参数为摇杆底盘和摇杆的纹理区域，第六个参数为pTimeBetweenUpdates界面的更新
final AnalogOnScreenControl velocityOnScreenControl = new AnalogOnScreenControl(x1, y1, this.mCamera, this.mOnScreenControlBaseTextureRegion, this.mOnScreenControlKnobTextureRegion, 0.1f, new IAnalogOnScreenControlListener() {											//备注1
@Override
public void onControlChange(final BaseOnScreenControl pBaseOnScreenControl, final float pValueX, final float pValueY) {
Log.i("test","x1:"+x1+",y1:"+y1+",pValueX:"+pValueX+",pValueY:"+pValueY);
face.setVelocity(pValueX * 100, pValueY * 100);	//备注2
}
@Override
public void onControlClick(final AnalogOnScreenControl pAnalogOnScreenControl) {	//备注3
/* Nothing. */
}
});
velocityOnScreenControl.getControlBase().setBlendFunction(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);											//备注4
velocityOnScreenControl.getControlBase().setAlpha(0.5f);
scene.setChildScene(velocityOnScreenControl);
//-------------------------------------------------------end 坐摇杆的实现------------------------------------------------------------//-------------------------------------------------------以下为右摇杆的实现----------------------------------------------------------
final int y2 = (this.mPlaceOnScreenControlsAtDifferentVerticalLocations) ? 0 : y1;
final int x2 = CAMERA_WIDTH - this.mOnScreenControlBaseTextureRegion.getWidth();
final AnalogOnScreenControl rotationOnScreenControl = new AnalogOnScreenControl(x2, y2, this.mCamera, this.mOnScreenControlBaseTextureRegion, this.mOnScreenControlKnobTextureRegion, 0.1f, new IAnalogOnScreenControlListener() {
@Override
public void onControlChange(final BaseOnScreenControl pBaseOnScreenControl, final float pValueX, final float pValueY) {
Log.i("test","x2:"+x2+",y2:"+y2+",pValueX:"+pValueX+",pValueY:"+pValueY);
if(pValueX == x1 && pValueY == x1) {
face.setRotation(x1);
} else {
face.setRotation(MathUtils.radToDeg((float)Math.atan2(pValueX, -pValueY)));	
//备注5
}
}
@Override
public void onControlClick(final AnalogOnScreenControl pAnalogOnScreenControl) {
/* Nothing. */
}
});
rotationOnScreenControl.getControlBase().setBlendFunction(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
rotationOnScreenControl.getControlBase().setAlpha(0.5f);
velocityOnScreenControl.setChildScene(rotationOnScreenControl);		//备注6
return scene;
}														//---------------------------------------------end 右摇杆的实现------------------------------------------------------------