飞机大战之三：添加子弹

首先了解CCSpriteBatchNode的使用（参考网址：http://www.cocos2dev.com/?p=331）
关于子弹的处理参考网址：http://blog.youkuaiyun.com/jackystudio/article/details/11859449

源码下载地址：点击打开链接

关于svn的简单使用：点击打开链接

在处理子弹时，我们是不是也一颗子弹一个精灵来渲染显示呢？我们知道，子弹往往连续很多的，
如果这样处理是不是很耗资源呢？对于同样的一类子弹有没有什么办法只渲染一次来减轻对资源的
压力呢？在cocos2d中就有这么一个类是CCSpriteBatchNode。
1.使用CCSprite创建1000个Icon.png精灵到场景中，这样就会渲染1000次

for(int i = 0;i < 1000;++i){
    int x = arc4random()%960;
    int y = arc4random()%640;
    CCSprite* testIcon = CCSprite::create("Icon.png");
    testIcon->setPosition( ccp(x, y) );
    this->addChild(testIcon);
}

运行如图：注意左下角最上面数字为1000.

2.当我们使用CCSpriteBatchNode时

CCSpriteBatchNode* batchNode = CCSpriteBatchNode::create("Icon.png", 1000);
batchNode->setPosition(CCPointZero);
this->addChild(batchNode);
 
for(int i = 0;i < 1000;++i){
    int x = arc4random()%960;
    int y = arc4random()%640;
    CCSprite* testIcon = CCSprite::createWithTexture(batchNode->getTexture());
    testIcon->setPosition( ccp(x, y) );
    batchNode->addChild(testIcon);
}

运行如图：注意左下角最上面数字为1.

其实我们可以这样理解，第一种方法是每次调用Icon.png都会重新解码一次，所以得解码1000次，肯定耗资源。
而对于第二种方法则是把Icon.png解码出来的数据保存在batchNode中，需要时只需要在内存中读取该
已经解码了的数据即可，显然只解码了一次，节约了资源。

下面进入飞机大战子弹类的创建

// BulletLayer.h
#ifndef __BULLETLAYER_H__
#define __BULLETLAYER_H__

#include "cocos2d.h"
#include "PlaneLayer.h"

USING_NS_CC;

class BulletLayer : public CCLayer
{
public:
    BulletLayer(void);
    ~BulletLayer(void);
    CREATE_FUNC(BulletLayer);
    virtual bool init();
    void AddBullet(float dt);
    void bulletMoveFinished(CCNode *pSender);
    void RemoveBullet(CCSprite* bullet);
    void StartShoot(float delay=0.0f);
    void StopShoot(void);

public:
    CCArray *m_pAllBullet;
    CCSpriteBatchNode *bulletBatchNode;
};

#endif

// BulletLayer.cpp
#include "BulletLayer.h"

BulletLayer::BulletLayer(void)
{
    m_pAllBullet = CCArray::create();
    m_pAllBullet->retain();
}

BulletLayer::~BulletLayer(void)
{
    m_pAllBullet->release();
    m_pAllBullet = NULL;
}

bool BulletLayer::init(void)
{
    bool bRet = false;

    do
    {
        CC_BREAK_IF(!CCLayer::init());
        CCTexture2D *texture = CCTextureCache::sharedTextureCache()->textureForKey("ui/shoot.png");
        bulletBatchNode = CCSpriteBatchNode::createWithTexture(texture);
        this->addChild(bulletBatchNode);
        bRet = true;
    }while(0);

    return bRet;
}

void BulletLayer::AddBullet(float dt)
{
    CCSprite *bullet = CCSprite::createWithSpriteFrameName("bullet1.png");
    bulletBatchNode->addChild(bullet);

    CCPoint planePosition=PlaneLayer::sharedPlane->getChildByTag(AIRPLANE)->getPosition();
    CCPoint bulletPosition=ccp(planePosition.x,
        planePosition.y + PlaneLayer::sharedPlane->getChildByTag(AIRPLANE)->getContentSize().height/2);
    bullet->setPosition(bulletPosition);

    float length = CCDirector::sharedDirector()->getWinSize().height 
        + bullet->getContentSize().height/2 - bulletPosition.y;
    float velocity = 420/1;
    float realMoveDuration = length/velocity;

    CCFiniteTimeAction *actionMove = CCMoveTo::create(realMoveDuration,
        ccp(bulletPosition.x, CCDirector::sharedDirector()->getWinSize().height + bullet->getContentSize().height/2));
    CCFiniteTimeAction *actionDone = CCCallFuncN::create(this,callfuncN_selector(BulletLayer::bulletMoveFinished));

    CCSequence *sequence = CCSequence::create(actionMove, actionDone,NULL);
    bullet->runAction(sequence);
}

void BulletLayer::StartShoot(float delay)
{
    this->schedule(schedule_selector(BulletLayer::AddBullet),0.20f,kCCRepeatForever,delay);
}

void BulletLayer::StopShoot(void)
{
    this->unschedule(schedule_selector(BulletLayer::AddBullet));
}

void BulletLayer::bulletMoveFinished(CCNode *pSender)
{
    CCSprite *bullet = (CCSprite *)pSender;
    m_pAllBullet->removeObject(bullet);
    this->bulletBatchNode->removeChild(bullet,true);
}

void BulletLayer::RemoveBullet(CCSprite* bullet)
{
    if (bullet!=NULL)
    {
        this->m_pAllBullet->removeObject(bullet);
        this->removeChild(bullet,true);
    }
}

GameLayer.h文件中添加头文件 #include "BulletLayer.h"以及类中增加成员变量 BulletLayer *bulletLayer;
GameLayer.cpp文件中构造中增加 bulletLayer = NULL; 在init中添加

        this->bulletLayer=BulletLayer::create();
        this->addChild(bulletLayer);
        this->bulletLayer->StartShoot();

把BulletLayer.h和BulletLayer.cpp添加进项目工程编译运行。

运行结果如下图：