Cocos2D-Android-1之源碼詳解：5.Box2dTest

package org.cocos2d.tests;

import java.util.Iterator;

import org.cocos2d.actions.UpdateCallback;
import org.cocos2d.config.ccMacros;
import org.cocos2d.events.CCTouchDispatcher;
import org.cocos2d.layers.CCLayer;
import org.cocos2d.layers.CCScene;
import org.cocos2d.nodes.CCDirector;
import org.cocos2d.nodes.CCLabel;
import org.cocos2d.nodes.CCSprite;
import org.cocos2d.nodes.CCSpriteSheet;
import org.cocos2d.opengl.CCGLSurfaceView;
import org.cocos2d.types.CGPoint;
import org.cocos2d.types.CGRect;
import org.cocos2d.types.CGSize;
import org.cocos2d.types.ccColor3B;

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.Window;
import android.view.WindowManager;

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

/** 
 * A test that demonstrates basic JBox2D integration by using AtlasSprites connected to physics bodies.
 * <br/>
 * <br/>
 * This implementation is based on the original Box2DTest (from cocos2d-iphone) but using the JBox2D
 * library and adjusting for differences with the new API as well as some differences in sensitivity
 * (and such) that were observed when testing on the Android platform.
 * 
 * @author Ray Cardillo
 */
// Box2dTest, there is a downloadable demo here:
//   http://code.google.com/p/cocos2d-android-1/downloads/detail?name=cocos2d%20%20and%20jbox2d.3gp&can=2&q=#makechanges
//
public class Box2dTest extends Activity {//物理盒子系統
    // private static final String LOG_TAG = JBox2DTest.class.getSimpleName();
    
	static {
        System.loadLibrary("gdx");//加載一個gdx庫
	}
	
    private CCGLSurfaceView mGLSurfaceView;//創建一個view

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);//無標題
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);//全屏
		getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON, 
				WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);//不黑屏

		mGLSurfaceView = new CCGLSurfaceView(this);//生成view，並關聯上下文到導演
		CCDirector director = CCDirector.sharedDirector();//生成得到導演（唯一）
		director.attachInView(mGLSurfaceView);//把view交給導演的list
		director.setDeviceOrientation(CCDirector.kCCDeviceOrientationLandscapeLeft);//橫屏
		setContentView(mGLSurfaceView);//把view映射刀屏幕
		
        // show FPS
        CCDirector.sharedDirector().setDisplayFPS(true);//顯示幀頻率

        // frames per second
        CCDirector.sharedDirector().setAnimationInterval(1.0f / 60.0f);//幀速

        CCScene scene = CCScene.node();//得到一個場景
        scene.addChild(new Box2DTestLayer());//把一個box的圖層添加到場景裡

        // Make the Scene active
        CCDirector.sharedDirector().runWithScene(scene);//讓導演運行這個場景，運行到剛才的view中
    }

    @Override
    public void onStart() {//開始方法
        super.onStart();

    }

    @Override
    public void onPause() {//暫停方法
        super.onPause();

        CCDirector.sharedDirector().onPause();
    }

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

        CCDirector.sharedDirector().onResume();
    }

    @Override
    public void onDestroy() {//銷毀方法
        super.onDestroy();

        CCDirector.sharedDirector().end();
        //CCTextureCache.sharedTextureCache().removeAllTextures();
    }


    //
    // Demo of calling integrating Box2D physics engine with cocos2d sprites
    // a cocos2d example
    // http://code.google.com/p/cocos2d-iphone
    //
    // by Steve Oldmeadow
    //
    static class Box2DTestLayer extends CCLayer {//以下是這個方法生成的方法
        public static final int kTagTileMap = 1;
        public static final int kTagSpriteManager = 1;
        public static final int kTagAnimation1 = 1;

		// Pixel to meters ratio. Box2D uses meters as the unit for measurement.
		// This ratio defines how many pixels correspond to 1 Box2D "meter"
		// Box2D is optimized for objects of 1x1 meter therefore it makes sense
		// to define the ratio so that your most common object type is 1x1 meter.
        protected static final float PTM_RATIO = 32.0f;
        
        // Simulation space should be larger than window per Box2D recommendation.
        protected static final float BUFFER = 1.0f;
        
        //FPS for the PhysicsWorld to sync to
        protected static final float FPS = (float)CCDirector.sharedDirector().getAnimationInterval();//得到整個動畫的幀頻率
        private static float rdelta = 0;
        
        protected final World bxWorld;//生成一個世界的引用..
        
        public Box2DTestLayer() {//構造方法
        	super();
        	
            this.setIsTouchEnabled(true);//可以點擊
        	this.setIsAccelerometerEnabled(true);//啟用設置加速，加速控制器可以啟動
            
        	CGSize s = CCDirector.sharedDirector().winSize();//得到屏幕的大小引用

      		// Define the gravity vector.
        	Vector2 gravity = new Vector2(9.8f, -9.8f);//定義一個二維向量

        	float scaledWidth = s.width/PTM_RATIO;//縮放寬
            float scaledHeight = s.height/PTM_RATIO;//縮放高

//        	Vector2 lower = new Vector2(-BUFFER, -BUFFER);//更小
//        	Vector2 upper = new Vector2(scaledWidth+BUFFER, scaledHeight+BUFFER);//更大
        	        	
        	bxWorld = new World(gravity, true);//新建並設置這個世界的重力向量
        	bxWorld.setContinuousPhysics(true);//連續物理可用

    		// Define the ground body.
            BodyDef bxGroundBodyDef = new BodyDef();//定義地面身體
            bxGroundBodyDef.position.set(0.0f, 0.0f);//身體的位置
    		
    		// Call the body factory which allocates memory for the ground body
    		// from a pool and creates the ground box shape (also from a pool).
    		// The body is also added to the world.
            Body groundBody = bxWorld.createBody(bxGroundBodyDef);//將身體添加到世界

         // Define the ground box shape.
            EdgeShape groundBox = new EdgeShape();//定義一個形狀

            Vector2 bottomLeft = new Vector2(0f,0f);//定義4個2維向量
            Vector2 topLeft = new Vector2(0f,scaledHeight);
            Vector2 topRight = new Vector2(scaledWidth,scaledHeight);
            Vector2 bottomRight = new Vector2(scaledWidth,0f);
            
    		// bottom
    		groundBox.set( bottomLeft, bottomRight );//設置一條線
    		groundBody.createFixture(groundBox,0);//把這條線作為物理盒子的邊界
    		
    		// top
    		groundBox.set( topLeft, topRight );//同理
    		groundBody.createFixture(groundBox,0);
    		
    		// left
    		groundBox.set( topLeft, bottomLeft );
    		groundBody.createFixture(groundBox,0);
    		
    		// right
    		groundBox.set( topRight, bottomRight );
    		groundBody.createFixture(groundBox,0);
                                    
            //Set up sprite
             CCSpriteSheet mgr = CCSpriteSheet.spriteSheet("blocks.png", 150);
//建立一個圖像表單，用來拆分出小塊
            addChild(mgr, 0, kTagSpriteManager);//表單添加進去，順序0，把標簽號定為1
    		
            addNewSpriteWithCoords(CGPoint.ccp(s.width / 2.0f, s.height / 2.0f));
            //上面是一個方法下面解釋
            CCLabel label = CCLabel.makeLabel("Tap screen", "DroidSans", 32);//創建一個標記
            label.setPosition(CGPoint.make(s.width / 2f, s.height - 50f));//設置坐標
            label.setColor(new ccColor3B(0, 0, 255));//設置顏色
            addChild(label);
        }

        private UpdateCallback tickCallback = new UpdateCallback() {//創建一個時間返回
			
			@Override
			public void update(float d) {//時間更新
				tick(d);
			}
		};
        
		@Override
		public void onEnter() {
			super.onEnter();
			
			// start ticking (for physics simulation)
			schedule(tickCallback);
		}

		@Override
		public void onExit() {
			super.onExit();
			
			// stop ticking (for physics simulation)			
			unschedule(tickCallback);
		}

		private void addNewSpriteWithCoords(CGPoint pos) {
      		CCSpriteSheet sheet = (CCSpriteSheet) getChildByTag(kTagSpriteManager);//得到一個表格

    		//We have a 64x64 sprite sheet with 4 different 32x32 images.  The following code is
    		//just randomly picking one of the images
    		int idx = (ccMacros.CCRANDOM_0_1() > .5 ? 0:1);//定義一個隨機數。得到1/0
    		int idy = (ccMacros.CCRANDOM_0_1() > .5 ? 0:1);
   
//    		CCSprite sprite = CCSprite.sprite("blocks.png", CGRect.make(32 * idx,32 * idy,32,32));//生成一個精靈。用那個圖片，截取公式位置的圖像
//    		this.addChild(sprite);//添加精靈
    		CCSprite sprite = CCSprite.sprite(sheet, CGRect.make(32 * idx,32 * idy,32,32));//生成精靈，用剛才的那個圖集，截取某塊
    		sheet.addChild(sprite);//添加子類
    		
    		sprite.setPosition(pos);  //設置點  		

    		// Define the dynamic body.
    		//Set up a 1m squared box in the physics world
    		BodyDef bodyDef = new BodyDef();//新建一個剛體
    		bodyDef.type = BodyType.DynamicBody;//設置為類型3動態剛體
    		bodyDef.position.set(pos.x/PTM_RATIO, pos.y/PTM_RATIO);//設置身體位置
    		
    		// Define another box shape for our dynamic body.
    		PolygonShape dynamicBox = new PolygonShape();//新建多邊形

    		dynamicBox.setAsBox(.5f, .5f);//These are mid points for our 1m box
//作為一個盒子時的頂點0.5,0.5
//    		dynamicBox.density = 1.0f;
//            dynamicBox.friction = 0.3f;
    		
        	synchronized (bxWorld) {//線程鎖
        		// Define the dynamic body fixture and set mass so it's dynamic.
        		Body body = bxWorld.createBody(bodyDef);//在世界內創建這個剛體
        		body.setUserData(sprite);//使用這個數據精靈
        		
        		FixtureDef fixtureDef = new FixtureDef();//固定的東西
        		fixtureDef.shape = dynamicBox;	
        		fixtureDef.density = 1.0f;//密度
        		fixtureDef.friction = 0.3f;//摩擦系數
        		body.createFixture(fixtureDef);//把這些固定參數給這個物體
        	}        	
        }
		

        public synchronized void tick(float delta) {//時間類
        	if ((rdelta += delta) < FPS) return;//計算得不用快過幀..
        	
        	// It is recommended that a fixed time step is used with Box2D for stability
        	// of the simulation, however, we are using a variable time step here.
        	// You need to make an informed choice, the following URL is useful
        	// http://gafferongames.com/game-physics/fix-your-timestep/
        	
        	// Instruct the world to perform a simulation step. It is
        	// generally best to keep the time step and iterations fixed.
        	synchronized (bxWorld) {
        		bxWorld.step(FPS, 8, 1);//計算的速度
        	}
	        	
        	rdelta = 0;//累計時間
        	
        	// Iterate over the bodies in the physics world
        	Iterator<Body> it = bxWorld.getBodies();//新建迭代器得到世界的剛體集合
        	while(it.hasNext()) {
        		Body b = it.next();//得到剛體
        		Object userData = b.getUserData();//剛體的數據
        		
        		if (userData != null && userData instanceof CCSprite) {
//如果數據不為空，且是個精靈的實例而
        			//Synchronize the Sprites position and rotation with the corresponding body
        			final CCSprite sprite = (CCSprite)userData;//得到這個圖像
        			final Vector2 pos = b.getPosition();//得到這個剛體的點
        			sprite.setPosition(pos.x * PTM_RATIO, pos.y * PTM_RATIO);
//設置點
        			sprite.setRotation(-1.0f * ccMacros.CC_RADIANS_TO_DEGREES(b.getAngle()));//設置弧度
        		}	
        	}
        }

        @Override
        public boolean ccTouchesBegan(MotionEvent event) {//觸屏事件
            CGPoint location = CCDirector.sharedDirector()
            	.convertToGL(CGPoint.make(event.getX(), event.getY()));//得到點

            addNewSpriteWithCoords(location);//添加一個物品在那個點
 
            return CCTouchDispatcher.kEventHandled;//返回數據
        }

        static float prevX=0, prevY=0;
        
        Vector2 gravity = new Vector2();//定義2維數組
        
		@Override
	    public void ccAccelerometerChanged(float accelX, float accelY, float accelZ) {//當加速傳感器有感覺了

			//#define kFilterFactor 0.05f
			float kFilterFactor  = 1.0f;	// don't use filter. the code is here just as an example

			float accX = (float) accelX * kFilterFactor + (1- kFilterFactor)* prevX;//x方向
			float accY = (float) accelY * kFilterFactor + (1- kFilterFactor)* prevY;//y方向
			
			prevX = accX;
			prevY = accY;		
			
			// no filtering being done in this demo (just magnify the gravity a bit)
			gravity.set( accY * 9.8f, accX * -9.8f );//得到重力的向量
			bxWorld.setGravity( gravity );		//給世界設置重力向量	
		}
		
    }
}