cocos2dx 中的动作机制 动作在引擎中的行为

_鞋男原创 BLOG： http://blog.csdn.net/wushao126/article/details/41077297

在cocos2dx 2.x中：runAction的函数

CCAction * CCNode::runAction(CCAction* action){    CCAssert( action != NULL, "Argument must be non-nil");    m_pActionManager->addAction(action, this, !m_bRunning);    return action;}

由此可见，但凡继承自CCNode的都具有行为。

CCActionManager *m_pActionManager;  ///< a pointer to ActionManager singleton, which is used to handle all the actions  

其实就是

CCDirector *director = CCDirector::sharedDirector();m_pActionManager = director->getActionManager();

void CCActionManager::addAction(CCAction *pAction, CCNode *pTarget, bool paused){    CCAssert(pAction != NULL, "");    CCAssert(pTarget != NULL, "");    tHashElement *pElement = NULL;    // we should convert it to CCObject*, because we save it as CCObject*    CCObject *tmp = pTarget;    HASH_FIND_INT(m_pTargets, &tmp, pElement);//查找    if (! pElement)    {        pElement = (tHashElement*)calloc(sizeof(*pElement), 1);        pElement->paused = paused;        pTarget->retain();        pElement->target = pTarget;        HASH_ADD_INT(m_pTargets, target, pElement);    }     actionAllocWithHashElement(pElement);//检测容量      CCAssert(! ccArrayContainsObject(pElement->actions, pAction), "");     ccArrayAppendObject(pElement->actions, pAction);//只看这句      pAction->startWithTarget(pTarget);//还有这句}

void ccArrayAppendObject(ccArray *arr, CCObject* object){    CCAssert(object != NULL, "Invalid parameter!");    object->retain();arr->arr[arr->num] = object;arr->num++;}

数据结构

typedef struct _hashElement{    struct _ccArray             *actions;    CCObject                    *target;    unsigned int                actionIndex;    CCAction                    *currentAction;    bool                        currentActionSalvaged;    bool                        paused;    UT_hash_handle                hh;} tHashElement;

通过pElement将Target和pAction配对

 

void CCAction::startWithTarget(CCNode *aTarget){    m_pOriginalTarget = m_pTarget = aTarget;}

将个action打上了标签，谁的action，绑定了执行者

以上就是对象的动作算是注册到了引擎了，现在看引擎怎么个程序。

在每帧绘制场景(drawScene)的时候会根据时间调度(schedule)，刷新界面（updata).

void CCActionManager::update(float dt){    for (tHashElement *elt = m_pTargets; elt != NULL; )    {        m_pCurrentTarget = elt;        m_bCurrentTargetSalvaged = false;        if (! m_pCurrentTarget->paused)        {            // The 'actions' CCMutableArray may change while inside this loop.            for (m_pCurrentTarget->actionIndex = 0; m_pCurrentTarget->actionIndex < m_pCurrentTarget->actions->num;                m_pCurrentTarget->actionIndex++)            {                m_pCurrentTarget->currentAction = (CCAction*)m_pCurrentTarget->actions->arr[m_pCurrentTarget->actionIndex];                if (m_pCurrentTarget->currentAction == NULL)                {                    continue;                }                m_pCurrentTarget->currentActionSalvaged = false;                m_pCurrentTarget->currentAction->step(dt);                if (m_pCurrentTarget->currentActionSalvaged)                {                    // The currentAction told the node to remove it. To prevent the action from                    // accidentally deallocating itself before finishing its step, we retained                    // it. Now that step is done, it's safe to release it.                    m_pCurrentTarget->currentAction->release();                } else                if (m_pCurrentTarget->currentAction->isDone())                {                    m_pCurrentTarget->currentAction->stop();                    CCAction *pAction = m_pCurrentTarget->currentAction;                    // Make currentAction nil to prevent removeAction from salvaging it.                    m_pCurrentTarget->currentAction = NULL;                    removeAction(pAction);                }                m_pCurrentTarget->currentAction = NULL;            }        }        // elt, at this moment, is still valid        // so it is safe to ask this here (issue #490)        elt = (tHashElement*)(elt->hh.next);        // only delete currentTarget if no actions were scheduled during the cycle (issue #481)        if (m_bCurrentTargetSalvaged && m_pCurrentTarget->actions->num == 0)        {            deleteHashElement(m_pCurrentTarget);        }    }    // issue #635    m_pCurrentTarget = NULL;}

哈希什么的不大懂啊，m_pTargets存放的是一个结构体tHashElement对象

HASH_ADD_INT(m_pTargets, target, pElement);

这里调用太深了，

m_pCurrentTarget->currentAction->step(dt);

这步将会调用到具体的Action的step，
接下来大家可以看我转载的一篇，懒得写了 2.x 和3.x 的机制是一样的

Cocos2dx 3.0游戏开发找小三之Cocos2d-x的动作机制：嘻，善哉！技盖至此乎？