cocos2dx进阶学习之场景切换

背景

在学习马里奥时，我们学习到从菜单场景到游戏场景的切换，代码如下

void CMMenuScene::OnStartCallBack( CCObject *pSender )
{
	CCDirector* pDirector = CCDirector::sharedDirector();
	CCScene *pScene = CMGameScene::CreateGameScene();
	pDirector->replaceScene(pScene);
}

上面的代码调用了CCDirector::replaceScene函数去进行场景切换。

CCDirector和CCScene

在cocos2dx里，CCDirector和CCScene有很密切的关系，CCDirector是导演，负责CCScene的展示，切换，结束等工作，具体体现在成员函数中：

/** Enters the Director's main loop with the given Scene.
     * Call it to run only your FIRST scene.
     * Don't call it if there is already a running scene.
     *
     * It will call pushScene: and then it will call startAnimation
     */
    void runWithScene(CCScene *pScene);

    /** Suspends the execution of the running scene, pushing it on the stack of suspended scenes.
     * The new scene will be executed.
     * Try to avoid big stacks of pushed scenes to reduce memory allocation. 
     * ONLY call it if there is a running scene.
     */
    void pushScene(CCScene *pScene);

    /** Pops out a scene from the queue.
     * This scene will replace the running one.
     * The running scene will be deleted. If there are no more scenes in the stack the execution is terminated.
     * ONLY call it if there is a running scene.
     */
    void popScene(void);

    /** Pops out all scenes from the queue until the root scene in the queue.
     * This scene will replace the running one.
     * Internally it will call `popToSceneStackLevel(1)`
     */
    void popToRootScene(void);

    /** Pops out all scenes from the queue until it reaches `level`.
     If level is 0, it will end the director.
     If level is 1, it will pop all scenes until it reaches to root scene.
     If level is <= than the current stack level, it won't do anything.
     */
 	void popToSceneStackLevel(int level);

    /** Replaces the running scene with a new one. The running scene is terminated.
     * ONLY call it if there is a running scene.
     */
    void replaceScene(CCScene *pScene);

以上是CCDirector的关于CCScene的成员函数

void runWithScene(CCScene *pScene)：该函数是刚开始运行时，导演类展示场景

void pushScene(CCScene* scene)：该函数将新的scene压入栈。在程序中有一个栈，可以保存很多场景，这样方便后退之类的操作。

void popScene(void)：弹出，与pushScene对应

void popToRootScene(void)：弹出栈中除了第一个场景外的其他场景

void popToSceneStackLevel(int level)：弹出到制定位置的scene

void replaceScene(CCScene *pScene)：让新的scene代替栈中当前的场景

动画切换

有的时候，简单的场景切换显得单调，如果需要动画切换，则需要以下类之一：

HelloWorld2* scene = HelloWorld2::create();
	//CCDirector::sharedDirector()->replaceScene(CCTransitionFade::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionFadeBL::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionFadeTR::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionTurnOffTiles::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionTurnOffTiles::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionJumpZoom::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionMoveInL::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionPageTurn::create(1.2, (CCScene*)scene, false));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionRotoZoom::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionShrinkGrow::create(1.2, (CCScene*)scene));
	//CCDirector::sharedDirector()->replaceScene(CCTransitionSlideInL::create(1.2, (CCScene*)scene));
	CCDirector::sharedDirector()->replaceScene(CCTransitionCrossFade::create(1.2, (CCScene*)scene));

使用切换场景来进行场景切换，切换场景类如下所列：

CCTransitionRotoZoom//从大到小画面缩小并跳动进入
CCTransitionJumpZoom//立体从左边缩小跳动进入
CCTransitionMoveInL//从左边移动进入右边
CCTransitionMoveInR//从右边移动进入左边
CCTransitionMoveInT//从上边移动到入下边
CCTransitionMoveInB//从下边移动到入上边
CCTransitionSlideInL//从左边移动入右边
CCTransitionSlideInR//从右边移动入左边
CCTransitionSlideInT//从上边移动入下边
CCTransitionSlideInB//从下边移动入上边
CCTransitionShrinkGrow//从大到小在中间缩小进入
CCTransitionFlipX//从X轴方向立体翻转
CCTransitionFlipY//从Y轴方向立体翻转
CCTransitionFlipAngular//从右边头翻转进入
CCTransitionZoomFlipX//从X轴方向立体跳动翻转
CCTransitionZoomFlipY//从Y轴方向立体跳动翻转
CCTransitionZoomFlipAngular//从右边立体缩小翻转进入
CCTransitionFade//从中间渐变进入
CCTransitionCrossFade//从外围渐变进入
CCTransitionTurnOffTiles//从格子覆盖上层进入
CCTransitionSplitCols//竖直分三个方块切入
CCTransitionSplitRows//横向分三个方块切入
CCTransitionFadeTR//从左下角向右上角格子渐变进入
CCTransitionFadeBL//从右上角角向左下角格子渐变进入
CCTransitionFadeUp//从下向上渐变进入
CCTransitionFadeDown//从上向下渐变进入