cocos2dx打飞机项目笔记四：Enemy类和EnemyLayer类

Enemy类没什么内容，就create和init方法，根据参数来创建不同的敌机，头文件代码如下：

//飞机的类型
enum planeType {smallPlane, midPlane, bigPlane};

class Enemy : public CCSprite
{

public:

    void loseLife();
    
    CC_SYNTHESIZE(float, m_speed, Speed);
    CC_SYNTHESIZE(int, m_life, Life);
    CC_SYNTHESIZE(int, m_score, Score);
    CC_SYNTHESIZE(planeType, m_type, Type);

    ~Enemy();
    virtual bool init(planeType type, CCTexture2D* texture);
    static Enemy* create(planeType type, CCTexture2D* texture);

};

create和init方法实现如下：

Enemy* Enemy::create(planeType type, CCTexture2D* texture)
{
    Enemy *pRet = new Enemy(); 
    if (pRet && pRet->init(type, texture)) 
    { 
        pRet->autorelease(); 
        return pRet; 
    } 
    else 
    { 
        delete pRet; 
        pRet = NULL; 
        return NULL; 
    }
}

bool Enemy::init(planeType type, CCTexture2D* texture)
{
    bool bRet = false;
    do 
    {
        const char* fileName;
        float score = 0;
        int life = 0;
        float speed = 0;

        int random_speed = rand() % 6 + 2;


        switch (type)
        {
        case bigPlane:
            fileName = "enemy3_n1.png";
            life = 15;
            score = 100;
            break;

        case midPlane:
            fileName = "enemy2.png";
            life = 8;
            score = 50;
            break;

        case smallPlane:
            fileName = "enemy1.png";
            life = 1;
            score = 10;
            break;

        default:
            break;
        }
;
        CC_BREAK_IF(!CCSprite::initWithSpriteFrameName(fileName));

        this->m_score = score;
        this->m_life = life;
        this->m_speed = 50*random_speed;
        this->m_type = type;
        bRet = true;

    } while (0);

    return bRet;
}

EnemyLayer类则负责敌机除了创建之外的所有工作，包括开始启动创建方法、停止创建、移除敌机、敌机爆炸等。头文件：

class EnemyLayer : public cocos2d::CCLayer
{

protected:

    CCSize designResolutionSize;
    CCSpriteBatchNode* batchNode;

public:

    CCArray *m_enemys;

    EnemyLayer(void);
    ~EnemyLayer(void);
    virtual bool init();
    
    void startTakeEnemys(float dt);
    void stopTakeEnemy(void);

    void EnemyMoveToFinish(CCNode* pSender);
    void removeEnemy(CCNode* pTarget, void* enemy);
    void removeAllEnmeys();

    void addEnemy(float dt);

    void bomb(CCNode* pSender);
    
    CREATE_FUNC(EnemyLayer);
};

敌机的创建和子弹不同，还记得子弹的创建我是保证屏幕上只有一粒子弹的吧，敌机则不然，固定每隔多少时间就会创建

void EnemyLayer::startTakeEnemys(float dt)
{
    
    float delay = 1.0f;//多少秒后调用
    float interval = 0.3f;//调用时间间隔
    this->schedule(schedule_selector(EnemyLayer::addEnemy), interval, kCCRepeatForever, delay);
}

addEnemy和bomb方法实现：

void EnemyLayer::addEnemy(float dt)
{
    if (true)
    {
        int seed = 19;
        int random_planeType = rand() % seed + 1;//1~19
        planeType type;

        Enemy* enemy = NULL;

        //按概率随机生成大中小三种敌机，或者不产生
        //big
        if (random_planeType % 19 == 0)
        {
            type = bigPlane;
            SimpleAudioEngine::sharedEngine()->playEffect("music/big_spaceship_flying.wav",false);
        } 
        //mid
        else if(random_planeType % 5 == 0)
        {
            type = midPlane;
        }
        //small
        else if(random_planeType % 2 == 0)
        {
            type = smallPlane;
        }
        // no
        else
        {
            return;
        }
            
        enemy = Enemy::create(type, this->batchNode->getTexture());

        
        //初始位置(随机)
        CCSize winSize = CCDirector::sharedDirector()->getWinSize();
        float x = rand() % (int)(winSize.width - (int)enemy->boundingBox().size.width * 2) + enemy->boundingBox().size.width;
        float y = winSize.height - enemy->boundingBox().size.height/2;

        CCPoint position = ccp(x,y);

        enemy->setPosition(position);
        this->m_enemys->addObject(enemy);
        batchNode->addChild(enemy);

        //敌机的运动轨迹CCDirector::sharedDirector()->getWinSize()
        float length = enemy->getContentSize().height + designResolutionSize.height;//飞行距离，超出屏幕即结束
        float velocity = 10/1;//飞行速度：420pixel/sec
        float realMoveDuration = length/enemy->getSpeed();//飞行时间

        CCFiniteTimeAction* actionMove = CCMoveTo::create(realMoveDuration,ccp(x, -enemy->getContentSize().height));
        CCFiniteTimeAction* actionDone = CCCallFuncN::create(this,callfuncN_selector(EnemyLayer::EnemyMoveToFinish));//回调一个敌机结束处理函数

        CCSequence* sequence = CCSequence::create(actionMove,actionDone,NULL);

        enemy->runAction(sequence);

    }
    
}


void EnemyLayer::bomb(CCNode* pSender)
{

    CCAnimation *animationBomb = NULL;
    Enemy *enemy = (Enemy*) pSender;
    char bombMusciName[64];

    if (enemy->getType() == bigPlane)
    {
        sprintf(bombMusciName, "music/enemy3_down.wav");
        animationBomb = CCAnimationCache::sharedAnimationCache()->animationByName("animation_Enemy3Bomb");
    } 
    else if(enemy->getType() == midPlane)
    {
        sprintf(bombMusciName, "music/enemy2_down.wav");
        animationBomb = CCAnimationCache::sharedAnimationCache()->animationByName("animation_Enemy2Bomb");
    }
    else if(enemy->getType() == smallPlane)
    {
        sprintf(bombMusciName, "music/enemy1_down.wav");
        animationBomb = CCAnimationCache::sharedAnimationCache()->animationByName("animation_Enemy1Bomb");
    }

    SimpleAudioEngine::sharedEngine()->playEffect(bombMusciName, false);//开始播放背景音效，false表示不循环 

    CCActionInterval *action = CCScaleTo::create(0.5f, pSender->getScale() + 0.05f);
    CCCallFuncND *funcND = CCCallFuncND::create(this,callfuncND_selector(EnemyLayer::removeEnemy),(void*)pSender);
    CCFiniteTimeAction* seq = CCSequence::create(CCAnimate::create(animationBomb), funcND, NULL);

    pSender->stopAllActions();
    pSender->runAction(seq);

}

可以看得出，这两个方法其实放到Enemy类里也很正常完全没问题的，这个要看coder想怎么写了。另外，敌机飞出屏幕外时的删除和被子弹打中时爆炸的回收是不同，差一个爆炸效果，而子弹在这两种情况的处理是一样的。