使用AndEngine开发游戏之一

      人生写的第一个Android游戏，名字为炸弹专家，可以在github上找到。https://github.com/zl-leaf/BombExpert。各位欢迎吐嘈。

    这个游戏使用的是AndEngine的库，链接为 https://github.com/nicolasgramlich/AndEngine，另外还带有其他的库和Example。要用这个库来写游戏，有第一件事情当然是要搞清楚怎么用这些库了。下面就简单的说一下我对AndEngine提供的其中一个例子的理解。

    首先用github下载代码AndEngine和其他库以及Example，如图

与AndEngine相关的库

AndEngine的例子

导入到Eclipse里面，运行（建议用真机运行，因为虚拟机好像有些问题）。

下面要说的代码来自于AndEngineExamples中的一个例子，org.andengine.examples.game.racer里面的RacerGameActivity。

代码如下

package org.andengine.examples.game.racer;

import org.andengine.engine.camera.Camera;
import org.andengine.engine.camera.hud.controls.AnalogOnScreenControl;
import org.andengine.engine.camera.hud.controls.AnalogOnScreenControl.IAnalogOnScreenControlListener;
import org.andengine.engine.camera.hud.controls.BaseOnScreenControl;
import org.andengine.engine.options.EngineOptions;
import org.andengine.engine.options.ScreenOrientation;
import org.andengine.engine.options.resolutionpolicy.RatioResolutionPolicy;
import org.andengine.entity.primitive.Rectangle;
import org.andengine.entity.scene.Scene;
import org.andengine.entity.scene.background.Background;
import org.andengine.entity.sprite.Sprite;
import org.andengine.entity.sprite.TiledSprite;
import org.andengine.entity.util.FPSLogger;
import org.andengine.extension.physics.box2d.FixedStepPhysicsWorld;
import org.andengine.extension.physics.box2d.PhysicsConnector;
import org.andengine.extension.physics.box2d.PhysicsFactory;
import org.andengine.extension.physics.box2d.PhysicsWorld;
import org.andengine.extension.physics.box2d.util.Vector2Pool;
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.opengl.texture.region.TiledTextureRegion;
import org.andengine.opengl.vbo.VertexBufferObjectManager;
import org.andengine.ui.activity.SimpleBaseGameActivity;
import org.andengine.util.math.MathUtils;

import android.opengl.GLES20;

import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.Body;
import com.badlogic.gdx.physics.box2d.BodyDef.BodyType;
import com.badlogic.gdx.physics.box2d.FixtureDef;

/**
 * (c) 2010 Nicolas Gramlich
 * (c) 2011 Zynga
 *
 * @author Nicolas Gramlich
 * @since 22:43:20 - 15.07.2010
 */
public class RacerGameActivity extends SimpleBaseGameActivity {
	// ===========================================================
	// Constants
	// ===========================================================

	private static final int RACETRACK_WIDTH = 64;

	private static final int OBSTACLE_SIZE = 16;
	private static final int CAR_SIZE = 16;

	private static final int CAMERA_WIDTH = RACETRACK_WIDTH * 5;
	private static final int CAMERA_HEIGHT = RACETRACK_WIDTH * 3;

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

	private Camera mCamera;

	private BitmapTextureAtlas mVehiclesTexture;
	private TiledTextureRegion mVehiclesTextureRegion;

	private BitmapTextureAtlas mBoxTexture;
	private ITextureRegion mBoxTextureRegion;

	private BitmapTextureAtlas mRacetrackTexture;
	private ITextureRegion mRacetrackStraightTextureRegion;
	private ITextureRegion mRacetrackCurveTextureRegion;

	private BitmapTextureAtlas mOnScreenControlTexture;
	private ITextureRegion mOnScreenControlBaseTextureRegion;
	private ITextureRegion mOnScreenControlKnobTextureRegion;

	private Scene mScene;

	private PhysicsWorld mPhysicsWorld;

	private Body mCarBody;
	private TiledSprite mCar;

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

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

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

	@Override
	public EngineOptions onCreateEngineOptions() {
		this.mCamera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);

		return new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), this.mCamera);
	}

	@Override
	public void onCreateResources() {
		BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

		this.mVehiclesTexture = new BitmapTextureAtlas(this.getTextureManager(), 128, 16, TextureOptions.BILINEAR);
		this.mVehiclesTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mVehiclesTexture, this, "vehicles.png", 0, 0, 6, 1);
		this.mVehiclesTexture.load();

		this.mRacetrackTexture = new BitmapTextureAtlas(this.getTextureManager(), 128, 256, TextureOptions.REPEATING_NEAREST);
		this.mRacetrackStraightTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mRacetrackTexture, this, "racetrack_straight.png", 0, 0);
		this.mRacetrackCurveTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mRacetrackTexture, this, "racetrack_curve.png", 0, 128);
		this.mRacetrackTexture.load();

		this.mOnScreenControlTexture = new BitmapTextureAtlas(this.getTextureManager(), 256, 128, TextureOptions.BILINEAR);
		this.mOnScreenControlBaseTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mOnScreenControlTexture, this, "onscreen_control_base.png", 0, 0);
		this.mOnScreenControlKnobTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mOnScreenControlTexture, this, "onscreen_control_knob.png", 128, 0);
		this.mOnScreenControlTexture.load();

		this.mBoxTexture = new BitmapTextureAtlas(this.getTextureManager(), 32, 32, TextureOptions.BILINEAR);
		this.mBoxTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(this.mBoxTexture, this, "box.png", 0, 0);
		this.mBoxTexture.load();
	}

	@Override
	public Scene onCreateScene() {
		this.mEngine.registerUpdateHandler(new FPSLogger());

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

		this.mPhysicsWorld = new FixedStepPhysicsWorld(30, new Vector2(0, 0), false, 8, 1);

		this.initRacetrack();
		this.initRacetrackBorders();
		this.initCar();
		this.initObstacles();
		this.initOnScreenControls();

		this.mScene.registerUpdateHandler(this.mPhysicsWorld);

		return this.mScene;
	}

	@Override
	public void onGameCreated() {

	}

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

	private void initOnScreenControls() {
		final AnalogOnScreenControl analogOnScreenControl = new AnalogOnScreenControl(0, CAMERA_HEIGHT - this.mOnScreenControlBaseTextureRegion.getHeight(), this.mCamera, this.mOnScreenControlBaseTextureRegion, this.mOnScreenControlKnobTextureRegion, 0.1f, this.getVertexBufferObjectManager(), new IAnalogOnScreenControlListener() {
			@Override
			public void onControlChange(final BaseOnScreenControl pBaseOnScreenControl, final float pValueX, final float pValueY) {
				final Body carBody = RacerGameActivity.this.mCarBody;

				final Vector2 velocity = Vector2Pool.obtain(pValueX * 5, pValueY * 5);
				carBody.setLinearVelocity(velocity);
				Vector2Pool.recycle(velocity);

				final float rotationInRad = (float)Math.atan2(-pValueX, pValueY);
				carBody.setTransform(carBody.getWorldCenter(), rotationInRad);

				RacerGameActivity.this.mCar.setRotation(MathUtils.radToDeg(rotationInRad));
			}

			@Override
			public void onControlClick(final AnalogOnScreenControl pAnalogOnScreenControl) {
				/* Nothing. */
			}
		});
		analogOnScreenControl.getControlBase().setBlendFunction(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
		analogOnScreenControl.getControlBase().setAlpha(0.5f);
		//		analogOnScreenControl.getControlBase().setScaleCenter(0, 128);
		//		analogOnScreenControl.getControlBase().setScale(0.75f);
		//		analogOnScreenControl.getControlKnob().setScale(0.75f);
		analogOnScreenControl.refreshControlKnobPosition();

		this.mScene.setChildScene(analogOnScreenControl);
	}

	private void initCar() {
		this.mCar = new TiledSprite(20, 20, CAR_SIZE, CAR_SIZE, this.mVehiclesTextureRegion, this.getVertexBufferObjectManager());
		this.mCar.setCurrentTileIndex(0);

		final FixtureDef carFixtureDef = PhysicsFactory.createFixtureDef(1, 0.5f, 0.5f);
		this.mCarBody = PhysicsFactory.createBoxBody(this.mPhysicsWorld, this.mCar, BodyType.DynamicBody, carFixtureDef);

		this.mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(this.mCar, this.mCarBody, true, false));

		this.mScene.attachChild(this.mCar);
	}

	private void initObstacles() {
		this.addObstacle(CAMERA_WIDTH / 2, RACETRACK_WIDTH / 2);
		this.addObstacle(CAMERA_WIDTH / 2, RACETRACK_WIDTH / 2);
		this.addObstacle(CAMERA_WIDTH / 2, CAMERA_HEIGHT - RACETRACK_WIDTH / 2);
		this.addObstacle(CAMERA_WIDTH / 2, CAMERA_HEIGHT - RACETRACK_WIDTH / 2);
	}

	private void addObstacle(final float pX, final float pY) {
		final Sprite box = new Sprite(pX, pY, OBSTACLE_SIZE, OBSTACLE_SIZE, this.mBoxTextureRegion, this.getVertexBufferObjectManager());

		final FixtureDef boxFixtureDef = PhysicsFactory.createFixtureDef(0.1f, 0.5f, 0.5f);
		final Body boxBody = PhysicsFactory.createBoxBody(this.mPhysicsWorld, box, BodyType.DynamicBody, boxFixtureDef);
		boxBody.setLinearDamping(10);
		boxBody.setAngularDamping(10);

		this.mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(box, boxBody, true, true));

		this.mScene.attachChild(box);
	}

	private void initRacetrack() {
		// Straights
		{
			final ITextureRegion racetrackHorizontalStraightTextureRegion = this.mRacetrackStraightTextureRegion.deepCopy();
			racetrackHorizontalStraightTextureRegion.setTextureWidth(3 * this.mRacetrackStraightTextureRegion.getWidth());

			final ITextureRegion racetrackVerticalStraightTextureRegion = this.mRacetrackStraightTextureRegion;

			// Top Straight 
			this.mScene.attachChild(new Sprite(RACETRACK_WIDTH, 0, 3 * RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackHorizontalStraightTextureRegion, this.getVertexBufferObjectManager()));
			// Bottom Straight
			this.mScene.attachChild(new Sprite(RACETRACK_WIDTH, CAMERA_HEIGHT - RACETRACK_WIDTH, 3 * RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackHorizontalStraightTextureRegion, this.getVertexBufferObjectManager()));

			// Left Straight
			final Sprite leftVerticalStraight = new Sprite(0, RACETRACK_WIDTH, RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackVerticalStraightTextureRegion, this.getVertexBufferObjectManager());
			leftVerticalStraight.setRotation(90);
			this.mScene.attachChild(leftVerticalStraight);
			// Right Straight
			final Sprite rightVerticalStraight = new Sprite(CAMERA_WIDTH - RACETRACK_WIDTH, RACETRACK_WIDTH, RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackVerticalStraightTextureRegion, this.getVertexBufferObjectManager());
			rightVerticalStraight.setRotation(90);
			this.mScene.attachChild(rightVerticalStraight);
		}

		// Edges
		{
			final ITextureRegion racetrackCurveTextureRegion = this.mRacetrackCurveTextureRegion;

			// Upper Left
			final Sprite upperLeftCurve = new Sprite(0, 0, RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackCurveTextureRegion, this.getVertexBufferObjectManager());
			upperLeftCurve.setRotation(90);
			this.mScene.attachChild(upperLeftCurve);

			// Upper Right 
			final Sprite upperRightCurve = new Sprite(CAMERA_WIDTH - RACETRACK_WIDTH, 0, RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackCurveTextureRegion, this.getVertexBufferObjectManager());
			upperRightCurve.setRotation(180);
			this.mScene.attachChild(upperRightCurve);

			// Lower Right 
			final Sprite lowerRightCurve = new Sprite(CAMERA_WIDTH - RACETRACK_WIDTH, CAMERA_HEIGHT - RACETRACK_WIDTH, RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackCurveTextureRegion, this.getVertexBufferObjectManager());
			lowerRightCurve.setRotation(270);
			this.mScene.attachChild(lowerRightCurve);

			// Lower Left
			final Sprite lowerLeftCurve = new Sprite(0, CAMERA_HEIGHT - RACETRACK_WIDTH, RACETRACK_WIDTH, RACETRACK_WIDTH, racetrackCurveTextureRegion, this.getVertexBufferObjectManager());
			this.mScene.attachChild(lowerLeftCurve);
		}
	}


	private void initRacetrackBorders() {
		final VertexBufferObjectManager vertexBufferObjectManager = this.getVertexBufferObjectManager();

		final Rectangle bottomOuter = new Rectangle(0, CAMERA_HEIGHT - 2, CAMERA_WIDTH, 2, vertexBufferObjectManager);
		final Rectangle topOuter = new Rectangle(0, 0, CAMERA_WIDTH, 2, vertexBufferObjectManager);
		final Rectangle leftOuter = new Rectangle(0, 0, 2, CAMERA_HEIGHT, vertexBufferObjectManager);
		final Rectangle rightOuter = new Rectangle(CAMERA_WIDTH - 2, 0, 2, CAMERA_HEIGHT, vertexBufferObjectManager);

		final Rectangle bottomInner = new Rectangle(RACETRACK_WIDTH, CAMERA_HEIGHT - 2 - RACETRACK_WIDTH, CAMERA_WIDTH - 2 * RACETRACK_WIDTH, 2, vertexBufferObjectManager);
		final Rectangle topInner = new Rectangle(RACETRACK_WIDTH, RACETRACK_WIDTH, CAMERA_WIDTH - 2 * RACETRACK_WIDTH, 2, vertexBufferObjectManager);
		final Rectangle leftInner = new Rectangle(RACETRACK_WIDTH, RACETRACK_WIDTH, 2, CAMERA_HEIGHT - 2 * RACETRACK_WIDTH, vertexBufferObjectManager);
		final Rectangle rightInner = new Rectangle(CAMERA_WIDTH - 2 - RACETRACK_WIDTH, RACETRACK_WIDTH, 2, CAMERA_HEIGHT - 2 * RACETRACK_WIDTH, vertexBufferObjectManager);

		final FixtureDef wallFixtureDef = PhysicsFactory.createFixtureDef(0, 0.5f, 0.5f);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, bottomOuter, BodyType.StaticBody, wallFixtureDef);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, topOuter, BodyType.StaticBody, wallFixtureDef);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, leftOuter, BodyType.StaticBody, wallFixtureDef);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, rightOuter, BodyType.StaticBody, wallFixtureDef);

		PhysicsFactory.createBoxBody(this.mPhysicsWorld, bottomInner, BodyType.StaticBody, wallFixtureDef);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, topInner, BodyType.StaticBody, wallFixtureDef);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, leftInner, BodyType.StaticBody, wallFixtureDef);
		PhysicsFactory.createBoxBody(this.mPhysicsWorld, rightInner, BodyType.StaticBody, wallFixtureDef);

		this.mScene.attachChild(bottomOuter);
		this.mScene.attachChild(topOuter);
		this.mScene.attachChild(leftOuter);
		this.mScene.attachChild(rightOuter);

		this.mScene.attachChild(bottomInner);
		this.mScene.attachChild(topInner);
		this.mScene.attachChild(leftInner);
		this.mScene.attachChild(rightInner);
	}

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

这个类继承了SimpleBaseGameActivity（由AndEngine提供），然后要重写四个方法onCreateEngineOptions()、onCreateResources()、onCreateScene()、onGameCreated()。

onCreateEngineOptions()里面要设置Engine的参数，基本照着写就可以了（如果要用到声音的话要加一些东西，之后说）。

onCreateResources()是加载资源。首先说一下BitmapTextureAtlas和ITextureRegion。

     BitmapTextureAtlas，可以理解成一块画布，ITextureRegion则是画布上的图形。     

BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

this.mVehiclesTexture = new BitmapTextureAtlas(this.getTextureManager(), 128, 16, TextureOptions.BILINEAR);
this.mVehiclesTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mVehiclesTexture, this, "vehicles.png", 0, 0, 6, 1);
		this.mVehiclesTexture.load();

    以这段代码为例。首先设定图片资源的路径是gfx（就是项目的assets/gfx）

BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

    新建一个宽高为128X16的BitmapTextureAtlasm VehiclesTexture

this.mVehiclesTexture = new BitmapTextureAtlas(this.getTextureManager(), 128, 16, TextureOptions.BILINEAR);

    在画布VehiclesTexture上画图

this.mVehiclesTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mVehiclesTexture, this, "vehicles.png", 0, 0, 6, 1);

    vehicles.png图片如下

,图的大小为96X16,然后画布的大小一定要比图片大而且是2的整数倍（不知道为什么），所以新建VehiclesTexture的大小为128X16。

     createTiledFromAsset里面的参数我是这么理解的，在VehiclesTexture上起点为（0,0）处画图vehicles.png，该图片可以以一行6列的格式分成6张小图。

    加载画布和画布上面的图片

this.mVehiclesTexture.load();

同样道理加载其他图片资源。

onCreateScene()，创造游戏的场景（Scene，一改可以理解成是游戏的容器或者背景吧）。

新建一个物理环境

this.mPhysicsWorld = new FixedStepPhysicsWorld(30, new Vector2(0, 0), false, 8, 1);

里面的参数意思可以自己查（因为有一两个我不是很理解）

然后就是要往Sence里面添加精灵（Sprite，可以理解成是一个单元，就像游戏中一个人物，一只怪物）。

最后注册物理环境

this.mScene.registerUpdateHandler(this.mPhysicsWorld);

下面以initCar()和initOnScreenControls()里面的代码来说一下

新建一个TiledSprite mCar，初始位置为（20,20），宽高为CAR_SIZEXCAR_SIZE的精灵，选用mVehiclesTextureRegion作为图片。

this.mCar = new TiledSprite(20, 20, CAR_SIZE, CAR_SIZE, this.mVehiclesTextureRegion, this.getVertexBufferObjectManager());

并且使用 mVehiclesTextureRegion中的第0个图案。（还记得之前设定好mVehiclesTextureRegion包含1行6列的小图不？现在用第0个）

this.mCar.setCurrentTileIndex(0);

生成一个实体作为车子（mCar）的身体

final FixtureDef carFixtureDef = PhysicsFactory.createFixtureDef(1, 0.5f, 0.5f);
this.mCarBody = PhysicsFactory.createBoxBody(this.mPhysicsWorld, this.mCar, BodyType.DynamicBody, carFixtureDef);

把车子（mCar）和车身（mCarBody）绑定在一起

this.mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(this.mCar, this.mCarBody, true, false));

在场景（Scene）中添加这一车子

this.mScene.attachChild(this.mCar);

这样一个initCar()就完成了。

下面是initOnScreenControls()，控制按钮的制作。

用mOnScreenControlBaseTextureRegion（操控按钮方向的那张图片）和mOnScreenControlKnobTextureRegion（那个圆圆的摇杆图片）制作AnalogOnScreenControl analogOnScreenControl，位于画面的（0, CAMERA_HEIGHT -this.mOnScreenControlBaseTextureRegion.getHeight()）处。

覆写onControlChange方法，当摇杆移动的时候车子运动。

final AnalogOnScreenControl analogOnScreenControl = new AnalogOnScreenControl(0, CAMERA_HEIGHT - this.mOnScreenControlBaseTextureRegion.getHeight(), this.mCamera, this.mOnScreenControlBaseTextureRegion, this.mOnScreenControlKnobTextureRegion, 0.1f, this.getVertexBufferObjectManager(), new IAnalogOnScreenControlListener() {
	@Override
	public void onControlChange(final BaseOnScreenControl pBaseOnScreenControl, final float pValueX, final float pValueY) {
		final Body carBody = RacerGameActivity.this.mCarBody;

		final Vector2 velocity = Vector2Pool.obtain(pValueX * 5, pValueY * 5);
		carBody.setLinearVelocity(velocity);
		Vector2Pool.recycle(velocity);

		final float rotationInRad = (float)Math.atan2(-pValueX, pValueY);
		carBody.setTransform(carBody.getWorldCenter(), rotationInRad);

		RacerGameActivity.this.mCar.setRotation(MathUtils.radToDeg(rotationInRad));
	}

	@Override
	public void onControlClick(final AnalogOnScreenControl pAnalogOnScreenControl) {
		/* Nothing. */
	}
});

然后就是各种注册，添加到Scene中

analogOnScreenControl.getControlBase().setBlendFunction(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);
analogOnScreenControl.getControlBase().setAlpha(0.5f);
analogOnScreenControl.refreshControlKnobPosition();

this.mScene.setChildScene(analogOnScreenControl);

这样操控按钮就完成了。

onGameCreated()是当所有加载渲染都搞定之后运行的方法，这里没有任何操作，所以空空的。

解说到此结束，这是我写的第一篇这么长的博文了，有些地方直接省略了，如果我说的有问题或者有疑问欢迎吐嘈一下