基于Cocos2d-x-1.0.1的飞机大战游戏开发实例（中）

接《基于Cocos2d-x-1.0.1的飞机大战游戏开发实例（上）》

三、代码分析

1.界面初始化

 bool PlaneWarGame::init()
 {
     bool bRet = false;
     do
     {
         CC_BREAK_IF(! CCLayer::init());

         _size = CCDirector::sharedDirector()->getWinSize();

         // 设置触摸可用
         this->setIsTouchEnabled(true);
         // 从窗口中取消息
         CCDirector::sharedDirector()->getOpenGLView()->SetWin32KeyLayer( this );

         // 初始化游戏背景
         CC_BREAK_IF(!initBackground());
         // 菜单1（暂停/声音/炸弹）
         CC_BREAK_IF(!initMenu1());
         // 菜单2（继续/重新开始/返回）
         CC_BREAK_IF(!initMenu2());
         // 菜单3（重新开始/返回）
         CC_BREAK_IF(!initMenu3());

         // 创建玩家飞机
         _player = new PlaySprite;
         _player->setPosition(CCPointZero);
         addChild(_player);

         // 调度器:定时调用自定义的回扫函数
         this->schedule( schedule_selector(PlaneWarGame::gameLoop));
         this->schedule( schedule_selector(PlaneWarGame::shoot), 0.1 );
         this->schedule( schedule_selector(PlaneWarGame::addEnemy), 0.3 );
         this->schedule( schedule_selector(PlaneWarGame::addProp),  );

         // 初始化两个数组
         _enemys = CCArray::array();
         _enemys->retain();
         _bullets = CCArray::array();
         _bullets->retain();

         // 背景音乐
         CocosDenshion::SimpleAudioEngine::sharedEngine()->playBackgroundMusic(
             "planewar/game_music.wav", true);

         bRet = true;
     } while ();

     return bRet;
 }

初始化的工作包括：

• 设置触摸可用
• 　　设置可自定义处理消息
• 初始化游戏背景
• 　　初始化三个菜单（界面菜单/游戏暂停时的菜单/游戏结束时的菜单）
• 　　初始化两个CCArray类型的数组，分别用来存储有效的敌机精灵对象和子弹对象
• 设置需要定时调用函数的调度器
• 设置背景音乐
• 添加玩家角色

2.初始化游戏背景

 bool PlaneWarGame::initBackground()
 {
     // 显示分数
     _label = CCLabelBMFont::labelWithString("","planewar/font.fnt");
     _label->setPosition(ccp(,_size.height-));
     _label->setColor(ccc3(,,));
     this->addChild(_label, );

     // 显示炸弹数量
     CCLabelBMFont* bombcount = CCLabelBMFont::labelWithString("X09","planewar/font.fnt");
     bombcount->setAnchorPoint(ccp(,));
     bombcount->setPosition(ccp(,));
     bombcount->setColor(ccc3(,,));
     addChild(bombcount, ,);

     // 添加背景
     CCSprite* bg1 = CCSprite::spriteWithFile("planewar/bg1.png");
     if (!bg1)return false;
     bg1->setAnchorPoint(ccp(,));
     bg1->setPosition( ccp(, _size.height) );
     this->addChild(bg1, , );

     bg1->runAction(
         CCSequence::actions(
         CCMoveBy::actionWithDuration(,ccp(,-)),
         CCCallFunc::actionWithTarget(this, callfunc_selector(PlaneWarGame::bg1roll)),NULL));

     CCSprite* bg2 = CCSprite::spriteWithFile("planewar/bg2.png");
     if (!bg1)return false;
     bg2->setAnchorPoint(ccp(,));
     bg2->setPosition( ccp(, _size.height*) );
     this->addChild(bg2, , );

     bg2->runAction(
         CCSequence::actions(
         CCMoveBy::actionWithDuration(,ccp(,-)),
         CCCallFunc::actionWithTarget(this, callfunc_selector(PlaneWarGame::bg2roll)),NULL));
     return true;
 }

 void PlaneWarGame::bg1roll(){
     //运动出屏幕重设位置，运动
     CCSprite * bg = (CCSprite *)getChildByTag();
     bg->setPosition(ccp(,));
     CCAction* seq = CCSequence::actions(
         CCMoveBy::actionWithDuration(,ccp(,-)),
         CCCallFunc::actionWithTarget(this, callfunc_selector(PlaneWarGame::bg1roll)),NULL);
     bg->runAction(seq);
 }

 void PlaneWarGame::bg2roll(){
     //运动出屏幕重设位置，运动
     CCSprite * bg = (CCSprite *)getChildByTag();
     bg->setPosition(ccp(,));
     CCAction* seq = CCSequence::actions(
         CCMoveBy::actionWithDuration(,ccp(,-)),
         CCCallFunc::actionWithTarget(this, callfunc_selector(PlaneWarGame::bg2roll)),NULL);
     bg->runAction(seq);
 }

初始化游戏背景时，需要注意的是：要做出飞机向上走的视觉效果，就要把背景向下滚动，这里使用两个背景bg1和bg2，大小分别为屏幕大小。初始bg1在屏幕内，bg2在屏幕上方，两个同事向下运动；当bg1刚刚运动到屏幕外，bg2刚好盖住屏幕，bg1挪到屏幕上方向下运动...循环操作，就能做出循环滚动的背景效果了。

3.子弹的处理

 // 确定子弹类型
 void PlaneWarGame::shoot(float dt)
 {
     if (_isOver)return;
     if(_player==NULL) return;

     if(_player->_bulletKind == BK_SINGLE)
     {
         CCSprite *bullet = CCSprite::spriteWithFile(
             "planewar/plane.png", CCRectMake(,,,));
         addBullet(bullet,_player->getPlayerPt());
     }else if (_player->_bulletKind == BK_DOUBLE)
     {
         CCSprite *bullet = CCSprite::spriteWithFile(
             "planewar/plane.png", CCRectMake(,,,));
         addBullet(bullet,ccp(_player->getPlayerPt().x-,_player->getPlayerPt().y));
         CCSprite *bullet1 = CCSprite::spriteWithFile(
             "planewar/plane.png", CCRectMake(,,,));
         addBullet(bullet1,ccp(_player->getPlayerPt().x+,_player->getPlayerPt().y));
     }
 }
 // 添加子弹
 void PlaneWarGame::addBullet(CCSprite* bullet, CCPoint pt)
 {
     bullet->setPosition(pt);
     this->addChild(bullet);

     bullet->runAction( CCSequence::actions(
         CCMoveTo::actionWithDuration(0.5, ccp(pt.x,_size.height+bullet->getContentSize().height/)),
         CCCallFuncN::actionWithTarget(this,callfuncN_selector(PlaneWarGame::spriteMoveFinished)),
         NULL) );

     bullet->setTag();
     _bullets->addObject(bullet);
 }
 // 回收
 void PlaneWarGame::spriteMoveFinished(CCNode* sender)
 {
     CCSprite *sprite = (CCSprite *)sender;
     this->removeChild(sprite, true);
     if (sprite->getTag()==)//子弹
         _bullets->removeObject(sprite);
 }

吃道具可改变子弹类型。子弹的回收方式：从飞机坐标处出发，运动到屏幕外被回收。道具的处理类似。

4.设置触摸/鼠标点击控制玩家角色的移动

 bool PlaneWarGame::ccTouchBegan(CCTouch *pTouch, CCEvent *pEvent)
 {
     if(_player==NULL) return false;

     CCPoint pt = CCDirector::sharedDirector()->convertToGL(
         pTouch->locationInView(pTouch->view()));

     CCRect rt = _player->getRect();
     if (CCRect::CCRectContainsPoint(rt,pt))
         _player->_isDragEnabled = true;
     return true;
 }

 void PlaneWarGame::ccTouchMoved(CCTouch *pTouch, CCEvent *pEvent)
 {
     if(_player==NULL) return;

     CCSize size = CCDirector::sharedDirector()->getWinSize();
     CCPoint pt = CCDirector::sharedDirector()->convertToGL(
         pTouch->locationInView(pTouch->view()));

     CCRect rt = CCRect(,,size.width,size.height);

     if (_player->_isDragEnabled && CCRect::CCRectContainsPoint(rt,pt))
         _player->setPlayerPt(pt);
 }

 void PlaneWarGame::ccTouchEnded(CCTouch *pTouch, CCEvent *pEvent)
 {
     _player->_isDragEnabled = false;
 }

这里重写3个虚函数。移动角色的方式：触摸/鼠标按下时，如果点击位置在角色上，将角色可被拖拽状态置为true;触摸/鼠标移动时，根据角色的可被拖拽状态和屏幕范围确定是否移动；触摸/鼠标弹起时，将角色的可被拖拽状态恢复为false。

5.碰撞检测

 void PlaneWarGame::updateGame(float dt)
 {
     CCArray *bulletsToDelete = CCArray::array();
     CCObject* it = NULL;
     CCObject* jt = NULL;

     if(_player==NULL) return;

     CCRect playerRect = _player->getRect();
     // 己方飞机和敌方飞机的碰撞
     CCARRAY_FOREACH(_enemys, jt)
     {
         EnemySprite *enemy = dynamic_cast<EnemySprite*>(jt);
         if (!enemy->isNull() && CCRect::CCRectIntersectsRect(playerRect, enemy->getRect()))
         {
             _player->die();
             gameover(false);
             return;
         }
     }

     //////////////////////////////////////////////////////////////////////////
         // 道具和角色的碰撞检测
     CCSprite* prop = (CCSprite*)getChildByTag();//子弹
     if (NULL != prop)
     {
         CCRect propRect = CCRectMake(
             prop->getPosition().x - (prop->getContentSize().width/),
             prop->getPosition().y - (prop->getContentSize().height/),
             prop->getContentSize().width,
             prop->getContentSize().height);
         if (CCRect::CCRectIntersectsRect(playerRect, propRect))
         {
             _player->_bulletKind = BK_DOUBLE;
             removeChild(prop,true);
             CocosDenshion::SimpleAudioEngine::sharedEngine()->
                 playEffect("planewar/get_double_laser.wav",false);
         }
     }
     CCSprite* prop1 = (CCSprite*)getChildByTag();//炸弹
     if (NULL != prop1)
     {
         CCRect prop1Rect = CCRectMake(
             prop1->getPosition().x - (prop1->getContentSize().width/),
             prop1->getPosition().y - (prop1->getContentSize().height/),
             prop1->getContentSize().width,
             prop1->getContentSize().height);
         if (CCRect::CCRectIntersectsRect(playerRect, prop1Rect))
         {
             _player->_bombCount++;
             removeChild(prop1,true);
             CocosDenshion::SimpleAudioEngine::sharedEngine()->
                 playEffect("planewar/get_bomb.wav",false);
         }
     }

     //////////////////////////////////////////////////////////////////////////
         // 子弹和敌机的碰撞检测
     CCARRAY_FOREACH(_bullets, it)
     for (int i=; i<_bullets->count(); i++)
     {
         CCSprite *bullet = dynamic_cast<CCSprite*>(_bullets->objectAtIndex(i));
         CCRect bulletRect = CCRectMake(
             bullet->getPosition().x - (bullet->getContentSize().width/),
             bullet->getPosition().y - (bullet->getContentSize().height/),
             bullet->getContentSize().width,
             bullet->getContentSize().height);

         CCArray* enemysToDelete =CCArray::array();

         CCARRAY_FOREACH(_enemys, jt)
         {
             EnemySprite *enemy = dynamic_cast<EnemySprite*>(jt);
             if (!enemy->_die && CCRect::CCRectIntersectsRect(bulletRect, enemy->getRect()))
             {
                 if (enemy->_hp>)
                 {
                     enemy->_hp--;
                     //bulletsToDelete->addObject(bullet);
                     _bullets->removeObject(bullet);
                     removeChild(bullet,true);
                 }
                 else if (enemy->_hp<=)
                 {
                     //bulletsToDelete->addObject(bullet);
                     _bullets->removeObject(bullet);
                     removeChild(bullet,true);
                     enemysToDelete->addObject(enemy);
                 }
             }
         }

         CCARRAY_FOREACH(enemysToDelete, jt)
         {
             EnemySprite *enemy = dynamic_cast<EnemySprite*>(jt);
             enemy->_die = true;
             enemy->die();
             _bulletsDestroyed++;
         }

         enemysToDelete->release();
     }

     // 释放已死亡的子弹
     CCARRAY_FOREACH(bulletsToDelete, it)
     {
         CCSprite* projectile = dynamic_cast<CCSprite*>(it);
         _bullets->removeObject(projectile);
         this->removeChild(projectile, true);
     }
     bulletsToDelete->release();
 }          

碰撞检测使用最简单的矩形检测。

6.玩家角色的添加和操作

 void PlaySprite::onEnter()
 {
     CCNode::onEnter();

     CCSize size = CCDirector::sharedDirector()->getWinSize();
     _sprite = CCSprite::spriteWithFile("planewar/hero1.png");
     _sprite->setContentSize(CCSize(,));
     _sprite->setPosition( ccp(size.width/,_sprite->getContentSize().height/) );
     addChild(_sprite,);

     CCAnimation * animation = CCAnimation::animation();
     animation->addFrameWithFileName("planewar/hero1.png");
     animation->addFrameWithFileName("planewar/hero2.png");
     CCAction* action = CCRepeatForever::actionWithAction(
         CCAnimate::actionWithDuration(0.1f, animation, false));
     action->setTag();
     _sprite->runAction(action);

     // 调度器
     schedule( schedule_selector(PlaySprite::move), 0.002 );
 }

 CCRect PlaySprite::getRect()
 {
     if (_sprite!=NULL)
         return CCRect(
         _sprite->getPosition().x - (_sprite->getContentSize().width/),
         _sprite->getPosition().y - (_sprite->getContentSize().height/),
         _sprite->getContentSize().width,
         _sprite->getContentSize().height);
 }    

 CCPoint PlaySprite::getPlayerPt()
 {
     if (_sprite!=NULL)
         return _sprite->getPosition();
 }

 void PlaySprite::setPlayerPt(CCPoint pt)
 {
     if (_sprite!=NULL)
         return _sprite->setPosition(pt);
 }

 void  PlaySprite::setMoveMode( UINT  message, WPARAM  wParam)
 {
     if (message == WM_KEYDOWN)
     {// 控制飞机移动
         if (wParam == VK_UP)
             _mode = MM_UP;
         else if (wParam == VK_DOWN)
             _mode = MM_DOWN;
         else if (wParam == VK_LEFT)
             _mode = MM_LEFT;
         else if (wParam == VK_RIGHT)
             _mode = MM_RIGHT;
     }else if (message == WM_KEYUP)
     {
         if (wParam == VK_UP || wParam == VK_DOWN ||wParam == VK_LEFT||wParam == VK_RIGHT)
             _mode = MM_NONE;
     }
 }

 void PlaySprite::move(float dt)
 {
     CCSize winSize = CCDirector::sharedDirector()->getWinSize();

     switch(_mode)
     {
     case MM_NONE:
         break;
     case MM_UP:
         if (getPlayerPt().y<winSize.height)
             setPlayerPt(ccp(getPlayerPt().x,getPlayerPt().y+));
         break;
     case MM_DOWN:
         if (getPlayerPt().y>)
             setPlayerPt(ccp(getPlayerPt().x,getPlayerPt().y-));
         break;
     case MM_LEFT:
         if (getPlayerPt().x>)
             setPlayerPt(ccp(getPlayerPt().x-,getPlayerPt().y));
         break;
     case  MM_RIGHT:
         if (getPlayerPt().x<winSize.width)
             setPlayerPt(ccp(getPlayerPt().x+,getPlayerPt().y));
         break;
     }
 }

 void PlaySprite::die()
 {
     if (_sprite==NULL)return;

     _sprite->stopActionByTag();
     CCAnimation * animation = CCAnimation::animation();
     animation->addFrameWithFileName("planewar/hero_blowup_n1.png");
     animation->addFrameWithFileName("planewar/hero_blowup_n2.png");
     animation->addFrameWithFileName("planewar/hero_blowup_n3.png");
     animation->addFrameWithFileName("planewar/hero_blowup_n4.png");
     _sprite->runAction(CCSequence::actions(
         CCAnimate::actionWithDuration(0.1f, animation, false),
         CCCallFunc::actionWithTarget(this, callfunc_selector(PlaySprite::destroy)),NULL));
 }

 void PlaySprite::destroy()
 {
     if (_sprite==NULL)return;

     removeChild(_sprite,true);
     _sprite = NULL;
 }

• 玩家角色类是派生自CCNode类，用组合的方式包含一个CCSprite类的成员对象，在玩家角色类内部封装对精灵的操作。
• 重写onEnter函数初始化_sprite成员，设置位置、大小、图片和帧动画等。
• 玩家的方向键控制移动和鼠标拖拽移动方式类似，在操作时设置移动状态，在schedule定时调用的函数move中根据移动状态来移动玩家角色。
• 关于碰撞之后的动画和销毁，参照上面的die和destroy函数，对象被碰撞时调用die函数运行爆炸的帧动画，动画结束后自动调用destroy函数销毁对象。
• 敌机对象的操作和玩家角色类似。

四、完成效果图

经过不到一周的时间，从什么都没有，到游戏正常运行、功能完整，体会了cocos2dx的调用机制。

下面是运行效果图：

如果实现中有什么问题，欢迎大家在评论中指教！