Android游戲開發十日通（6）- 太空大戰

今天要學習的是coscos2d-x官網索引的一篇初級游戲教程。作為小白的入門，再適合不過了。

資源文件下載

工程×××

大師的源碼

環境：

lubuntu 13.10 32bit  Android 4.1 cocos2d-x 2.2

下面就一步步來完成。

1.創建工程

在Eclipse中刷新工程，Resources文件夾就出現了。

換一個狂拽酷炫點的圖標

將android工程中res文件夾下的icon.png換成這個就可以了。

2.拷貝資源文件

將下載好的資源文件挨個拷貝到Resources文件夾中，注意Classes 文件夾不要拷貝，fonts文件夾合并就好。

3.添加一個小飛機 

先將HelloWorldScence.cpp中的

USING_NS_CC;

移動到HelloWorldScence.h中，這樣定義成員的時候就不用老加上命名空間了。

首先在HelloWorld.h中添加兩個成員：

private: 	CCSpriteBatchNode* batchNode; 	CCSprite* ship;

 batchNode = CCSpriteBatchNode::create("Spritesheets/Sprites.pvr.ccz");     this->addChild(batchNode);     CCSpriteFrameCache::sharedSpriteFrameCache()->addSpriteFramesWithFile("Spritesheets/Sprites.plist");          ship = CCSprite::createWithSpriteFrameName("SpaceFlier_sm_1.png");          ship->setPosition(ccp(origin.x + visibleSize.width * 0.1,                             origin.y + visibleSize.height * 0.5));     batchNode->addChild(ship,1);

4.添加卷軸滾動的背景

在頭文件中繼續添加幾個相關的private成員:

CCParallaxNode *backgroundNode;   CCSprite *spacedust1; CCSprite *spacedust2; CCSprite *planetsunrise; CCSprite *galaxy; CCSprite *spacialanomaly; CCSprite *spacialanomaly2;

這里用到了CCParallaxNode類，用它來實現背景，可以加強背景的層次感，在進行背景卷動的時候，可以實現越近的背景卷動得越快，越遠越慢。(想想在火車上 向外看窗外的景色)

   // 1) Create the CCParallaxNode     backgroundNode = CCParallaxNode::create();     this->addChild(backgroundNode, -1);          // 2) Create the sprites will be added to the CCParallaxNode     spacedust1 = CCSprite::create("Backgrounds/bg_front_spacedust.png");     spacedust2 = CCSprite::create("Backgrounds/bg_front_spacedust.png");     planetsunrise = CCSprite::create("Backgrounds/bg_planetsunrise.png");     galaxy = CCSprite::create("Backgrounds/bg_galaxy.png");     spacialanomaly = CCSprite::create("Backgrounds/bg_spacialanomaly.png");     spacialanomaly2 = CCSprite::create("Backgrounds/bg_spacialanomaly2.png");       // 3) Determine relative movement speeds for space dust and background     CCPoint dustSpeed = ccp(0.1, 0.1);     CCPoint bgSpeed = ccp(0.05, 0.05);       // 4) Add children to CCParallaxNode     backgroundNode->addChild(spacedust1, 0, dustSpeed, ccp(0,visibleSize.height/2) ); // 2     backgroundNode->addChild(spacedust2, 0, dustSpeed, ccp( spacedust1->getContentSize().width,visibleSize.height/2));     backgroundNode->addChild(galaxy, -1, bgSpeed, ccp(0, visibleSize.height * 0.7));     backgroundNode->addChild(planetsunrise, -1 , bgSpeed, ccp(600, visibleSize.height * 0));     backgroundNode->addChild(spacialanomaly, -1, bgSpeed, ccp(900, visibleSize.height * 0.3));     backgroundNode->addChild(spacialanomaly2, -1, bgSpeed, ccp(1500, visibleSize.height * 0.9));

5.卷動背景

原理就是每一Frame將背景向后移動一定的距離，也就是背景圖片以一定的速度運動。

在頭文件中添加update函數，將其聲明為似有成員函數，這個函數是會自動調用的。

private: 	// scheduled Update  	void update(float dt);

void HelloWorld::update(float dt) { 	CCPoint backgroundScrollVert = ccp(-1000,0); 	backgroundNode->setPosition(ccpAdd(backgroundNode->getPosition(), ccpMult(backgroundScrollVert, dt))); }

 this->scheduleUpdate();

而CCParallaxNode也沒有對應的循環的方法，這里就要自定義類了。這里自定義一個CCParallaxNodeExtras類，繼承 CCParallaxNode。主要是添加一個 incrementOffset() 方法，用戶實現循環顯示。

CCParallaxNodeExtras.h

#ifndef Cocos2DxFirstIosSample_CCParallaxNodeExtras_h #define Cocos2DxFirstIosSample_CCParallaxNodeExtras_h   #include "cocos2d.h"   USING_NS_CC;   class CCParallaxNodeExtras : public CCParallaxNode {       public :       // Need to provide a constructor      CCParallaxNodeExtras();       // just to avoid ugly later cast and also for safety     static CCParallaxNodeExtras * node();       // Facility method (it’s expected to have it soon in COCOS2DX)         void incrementOffset(CCPoint offset, CCNode* node);   } ;    #endif

#include "CCParallaxNodeExtras.h"    // Hack to access CCPointObject (which is not a public class) class CCPointObject  : CCObject {     CC_SYNTHESIZE(CCPoint, m_tRatio, Ratio)     CC_SYNTHESIZE(CCPoint, m_tOffset, Offset)     CC_SYNTHESIZE(CCNode *, m_pChild, Child)	// weak ref };   // Need to provide a constructor  CCParallaxNodeExtras::CCParallaxNodeExtras() {     CCParallaxNode(); // call parent constructor }   CCParallaxNodeExtras * CCParallaxNodeExtras::node() {     return new CCParallaxNodeExtras();        }   void CCParallaxNodeExtras::incrementOffset(CCPoint offset,CCNode* node){     for( unsigned int i = 0; i < m_pParallaxArray->num; i++) {         CCPointObject *point = (CCPointObject *)m_pParallaxArray->arr[i];         CCNode * curNode = point->getChild();         if( curNode->isEqual(node) ) {             point->setOffset( ccpAdd(point->getOffset(), offset) );             break;         }     } }

在這里還定義了一個內部類CCPointObject，關于CC_SYNTHESIZEz這個宏

#define CC_PROPERTY(varType, varName, funName)\  protected: varType varName;\  public: virtual varType get##funName(void);\  public: virtual void set##funName(varType var);

對原HelloWorldScence.cpp進行一定的修改,首先backgroundNode的聲明要修改：

	CCParallaxNodeExtras *backgroundNode;  

    backgroundNode = CCParallaxNodeExtras::node();

CCArray *spaceDusts = CCArray::arrayWithCapacity(2) ; spaceDusts->addObject(_spacedust1) ; spaceDusts->addObject(_spacedust2) ; for ( int ii = 0  ; ii <spaceDusts->count() ; ii++ ) {     CCSprite * spaceDust = (CCSprite *)(spaceDusts->objectAtIndex(ii)) ;     float xPosition = _backgroundNode->convertToWorldSpace(spaceDust->getPosition()).x  ;     float size = spaceDust->getContentSize().width ;     if ( xPosition < -size ) {         _backgroundNode->incrementOffset(ccp(spaceDust->getContentSize().width*2,0),spaceDust) ;      }                                    }   CCArray *backGrounds = CCArray::arrayWithCapacity(4) ; backGrounds->addObject(_galaxy) ; backGrounds->addObject(_planetsunrise) ; backGrounds->addObject(_spacialanomaly) ; backGrounds->addObject(_spacialanomaly2) ; for ( int ii = 0 ; ii <backGrounds->count() ; ii++ ) {     CCSprite * background = (CCSprite *)(backGrounds->objectAtIndex(ii)) ;     float xPosition = _backgroundNode->convertToWorldSpace(background->getPosition()).x ;     float size = background->getContentSize().width ;     if ( xPosition < -size ) {         _backgroundNode->incrementOffset(ccp(2000,0),background) ;      } }

SOURCES = main.cpp \         ../Classes/AppDelegate.cpp \         ../Classes/HelloWorldScene.cpp\         ../Classes/CCParallaxNodeExtras.cpp

android版本的編譯需要修改proj.android/jni/Android.mk

LOCAL_SRC_FILES := hellocpp/main.cpp \                    ../../Classes/AppDelegate.cpp \                    ../../Classes/HelloWorldScene.cpp\         	  ../../Classes/CCParallaxNodeExtras.cpp

5.夜空中最亮的星

我們還可以在場景中添加一些星空的效果，可以用內置的粒子系統來實現，在init() 的后面添加下面的語句：

//Add some stars     HelloWorld::addChild(CCParticleSystemQuad::create("Particles/Stars1.plist"));     HelloWorld::addChild(CCParticleSystemQuad::create("Particles/Stars2.plist"));     HelloWorld::addChild(CCParticleSystemQuad::create("Particles/Stars3.plist"));

6.控制小飛機

這里用到了移動設備的重力傳感器。cocos2d-x對加速計進行了封裝，我們可以不用關心具體平臺api，直接使用抽象后的加速計api就可以了。

首先是要實現基類的關于傳感器的虛函數，在頭文件中添加：

virtual void didAccelerate(CCAcceleration* pAccelerationValue);

void HelloWorld::didAccelerate(CCAcceleration* pAccelerationValue) {   #define KFILTERINGFACTOR 0.1   #define KRESTACCELX -0.6        #define KMAXDIFFY 0.2   #define KMAXDIFFX 0.1    double rollingX = 0.0;   double rollingY = 0.0;    // Cocos2DX inverts X and Y accelerometer depending on device orientation   // in landscape mode right x=-y and y=x !!! (Strange and confusing choice)   //exchange value   float tmp;   tmp = pAccelerationValue->x;   pAccelerationValue->x = pAccelerationValue->y;   pAccelerationValue->y = tmp;    rollingX = (pAccelerationValue->x * KFILTERINGFACTOR);   rollingY = (pAccelerationValue->y * KFILTERINGFACTOR);   float accelX = pAccelerationValue->x - rollingX;   float accelY = pAccelerationValue->y - rollingY;   CCSize winSize = CCDirector::sharedDirector()->getWinSize();   float accelDiffx = accelX - KRESTACCELX;   float accelDiffy = accelY;   float accelFractionx = accelDiffx / KMAXDIFFX;   float accelFractiony = accelDiffy / KMAXDIFFY;   shipPointsPerSecY = 0.5 * winSize.height * accelFractionx;   shipPointsPerSecX = 0.5 * winSize.width * accelFractiony; } 

這個函數在每次檢測到傳感器的信息之后就會回調，傳回一個CCAcceleration對象，這里只要x方向的值就可以了。注意這里還對傳感器的值進行了一定的處理，讓小飛機有一種飛行的感覺，同時速度是和屏幕大小對應的，算是多設備匹配的一個trick。

接下來在update() 中更行飛船的位置，在后面添加下面的代碼：

        CCSize winSize = CCDirector::sharedDirector()->getWinSize();         float maxY = winSize.height - ship->getContentSize().height/2;         float minY = ship->getContentSize().height/2;         float maxX = winSize.width - ship->getContentSize().width/2;         float minX = ship->getContentSize().width/2;          float diffy = (shipPointsPerSecY * dt);         float diffx = (shipPointsPerSecX * dt);         float newY = ship->getPosition().y + diffy;         float newX = ship->getPosition().x + diffx;         newY = MIN(MAX(newY, minY), maxY);         newX = MIN(MAX(newX, minX), maxX);         ship->setPosition(ccp(newX, newY)); 

最后就是啟動傳感器的檢測了，在init()中添加：

this->setAccelerometerEnabled(true);

7.添加小行星

在HelloWorld.h中添加幾個私有成員變量，

    CCArray* asteroids;     int nextAsteroid;     float nextAsteroidSpawn;

添加幾個public輔助函數：

    //For get random float value     float randomValueBetween(float low, float high);      //Set visibility of Node     void setInvisible(CCNode * node);      //Get millisecs current sys-time     float getTimeTick();

在init()中對成員進行初始化：

    //init asteroids     asteroids = new CCArray();     //Store asteroids     for(int i = 0; i < 15; ++i) {         CCSprite *asteroid = CCSprite::createWithSpriteFrameName("asteroid.png");         asteroid->setVisible(false);         batchNode->addChild(asteroid);         asteroids->addObject(asteroid);     }     nextAsteroid = 0;     nextAsteroidSpawn = 0.0;

float HelloWorld::randomValueBetween(float low, float high) {     return (((float) 2 * rand() / 0xFFFFFFFFu) * (high - low)) + low; }  float HelloWorld::getTimeTick() {     timeval time;     gettimeofday(&time, NULL);     unsigned long millisecs = (time.tv_sec * 1000) + (time.tv_usec/1000);     return (float) millisecs; }    void HelloWorld::setInvisible(CCNode * node) {     node->setVisible(false); }

    //Set asteroids     float curTimeMillis = getTimeTick();     if (curTimeMillis > nextAsteroidSpawn) {          float randMillisecs = randomValueBetween(0.20,1.0) * 1000;         nextAsteroidSpawn = randMillisecs + curTimeMillis;          float randY = randomValueBetween(0.0,winSize.height);         float randDuration = randomValueBetween(2.0,10.0);          CCSprite *asteroid = (CCSprite *)asteroids->objectAtIndex(nextAsteroid);         nextAsteroid++;          if (nextAsteroid >= (int)asteroids->count())             nextAsteroid = 0;          asteroid->stopAllActions();         asteroid->setPosition( ccp(winSize.width+asteroid->getContentSize().width/2, randY));         asteroid->setVisible(true);         asteroid->runAction(CCSequence::create(CCMoveBy::create(randDuration, ccp(-winSize.width-asteroid->getContentSize().width, 0)), CCCallFuncN::create(this, callfuncN_selector(HelloWorld::setInvisible)), NULL // DO NOT FORGET TO TERMINATE WITH NULL (unexpected in C++)          ));     }

8.發射激光

和小行星的添加類似，首先修改頭文件

    CCArray* shipLasers;     int nextShipLaser;

 //init lasers     shipLasers = new CCArray();     for(int i = 0; i < 5; ++i)     {         CCSprite *shipLaser = CCSprite::createWithSpriteFrameName("laserbeam_blue.png");         shipLaser->setVisible(false);         batchNode->addChild(shipLaser);         shipLasers->addObject(shipLaser);     }     this->setTouchEnabled(true);     nextShipLaser = 0; 

9.簡單的碰撞檢測

這里的碰撞檢測包括兩個部分：激光和小行星的碰撞，飛機和小行星的碰撞。

首先添加一個私有成員，用于記錄飛機的生命值。

int  lives;

在init()添加對其的初始化：

lives = 3;

在update()中添加檢測的操作：

   //Collision Detection     //Asteroids     CCObject* asteroid;     CCObject* shipLaser;     CCARRAY_FOREACH(asteroids, asteroid){         if (!((CCSprite *) asteroid)->isVisible() )             continue;         CCARRAY_FOREACH(shipLasers, shipLaser){             if (!((CCSprite *) shipLaser)->isVisible())                 continue;             if (((CCSprite *) shipLaser)->boundingBox().intersectsRect(((CCSprite *)asteroid)->boundingBox()) ) {                 ((CCSprite *)shipLaser)->setVisible(false);                 ((CCSprite *)asteroid)->setVisible(false);                 continue;             }         }         if (ship->boundingBox().intersectsRect(((CCSprite *)asteroid)->boundingBox()) ) {             ((CCSprite *)asteroid)->setVisible(false);             ship->runAction( CCBlink::create(1.0, 9));             lives--;         }     } 

10.終止游戲

理論上當飛機生命沒有的時候，游戲就要結束了。

這里游戲的勝利條件是堅持了60s，失敗條件是飛機被撞擊了三次。

添加一個枚舉聲明，表示游戲結束的原因：

typedef enum {   WIN,   LOSE } EndReason; 

添加私有成員：

double gameOverTime; bool gameOver;

    //Called when game ended     void endScene(EndReason endReason);      //Restart game     void restartTapped();

void HelloWorld::restartTapped() {     CCDirector::sharedDirector()->replaceScene     (CCTransitionZoomFlipX::create(0.5, this->scene()));     // reschedule     this->scheduleUpdate(); }  void HelloWorld::endScene( EndReason endReason ) {     if (gameOver)         return;     gameOver = true;      CCSize winSize = CCDirector::sharedDirector()->getWinSize();     char message[10] = "You Win";     if ( endReason == LOSE)         strcpy(message,"You Lose");     CCLabelBMFont * label ;     label = CCLabelBMFont::create(message, "fonts/Arial.fnt");     label->setScale(0.1);     label->setPosition(ccp(winSize.width/2 , winSize.height*0.6));     this->addChild(label);      CCLabelBMFont * restartLabel;     strcpy(message,"Restart");     restartLabel = CCLabelBMFont::create(message, "fonts/Arial.fnt");     CCMenuItemLabel *restartItem = CCMenuItemLabel::create(restartLabel, this, menu_selector(HelloWorld::restartTapped) );     restartItem->setScale(0.1);     restartItem->setPosition( ccp(winSize.width/2, winSize.height*0.4));      CCMenu *menu = CCMenu::create(restartItem, NULL);     menu->setPosition(CCPointZero);     this->addChild(menu);      // clear label and menu     restartItem->runAction(CCScaleTo::create(0.5, 1.0));     label ->runAction(CCScaleTo::create(0.5, 1.0));     // Terminate update callback     this->unscheduleUpdate(); } 

運行效果如下：

11.來點音效

游戲中的音效可以為游戲添色不少。

首先將蘋果的caf格式轉換成android支持的wav.終端cd到工程目錄下的 Resources/Sounds ,執行下面的命令（事先裝好ffmpeg）

ffmpeg -i SpaceGame.caf SpaceGame.wav
ffmpeg -i explosion_large.caf explosion_large.wav
ffmpeg -i  laser_ship.caf laser_ship.wav

順利的話Sounds文件夾下面就生成了轉好碼的音頻文件了。

在HelloWorld.h 中添加頭文件和命名空間：

#include "SimpleAudioEngine.h"  using namespace CocosDenshion;

在init() 中加入對音效的初始化，這里播放背景樂，同時預加載小行星爆炸的音效和發射激光的音效。

    SimpleAudioEngine::sharedEngine()->playBackgroundMusic("SpaceGame.wav",true);     SimpleAudioEngine::sharedEngine()->preloadEffect("explosion_large.wav");     SimpleAudioEngine::sharedEngine()->preloadEffect("laser_ship.wav"); 

在碰撞檢測中對應位置加入

 SimpleAudioEngine::sharedEngine()->playEffect("Sounds/explosion_large.wav");

在觸摸函數中添加

SimpleAudioEngine::sharedEngine()->playEffect("Sounds/laser_ship.wav");

發現linux版本不能正常編譯，報錯：

fatal error: SimpleAudioEngine.h: No such file or directory compilation terminated.

修改proj.linux/MakeFile

EXECUTABLE = SpaceGame  INCLUDES = -I.. -I../Classes \ 			    -I$(COCOS_ROOT)/CocosDenshion/include  SOURCES = main.cpp \         ../Classes/AppDelegate.cpp \         ../Classes/HelloWorldScene.cpp\         ../Classes/CCParallaxNodeExtras.cpp  COCOS_ROOT = ../../.. include $(COCOS_ROOT)/cocos2dx/proj.linux/cocos2dx.mk  SHAREDLIBS += -lcocos2d -lcocosdenshion COCOS_LIBS = $(LIB_DIR)/libcocos2d.so  $(TARGET): $(OBJECTS) $(STATICLIBS) $(COCOS_LIBS) $(CORE_MAKEFILE_LIST) 	@mkdir -p $(@D) 	$(LOG_LINK)$(CXX) $(CXXFLAGS) $(OBJECTS) -o $@ $(SHAREDLIBS) $(STATICLIBS)  $(OBJ_DIR)/%.o: %.cpp $(CORE_MAKEFILE_LIST) 	@mkdir -p $(@D) 	$(LOG_CXX)$(CXX) $(CXXFLAGS) $(INCLUDES) $(DEFINES) $(VISIBILITY) -c $< -o $@  $(OBJ_DIR)/%.o: ../%.cpp $(CORE_MAKEFILE_LIST) 	@mkdir -p $(@D) 	$(LOG_CXX)$(CXX) $(CXXFLAGS) $(INCLUDES) $(DEFINES) $(VISIBILITY) -c $< -o $@ 

主要是搜索路徑和庫的鏈接。然后linux版本就可以編譯了。

android版本直接編譯運行即可。

到此為止，已經基本完成了一個聲色俱全的移動平臺游戲了~

To be continue

可以做的還有很多，比如

1.給飛機添加血量的顯示；

2.添加爆炸的動畫；

3.添加敵機；

4.遭遇大boss

...

參考

Cocos2D-X Tutorial for iOS and Android: Space Game