cocos2d-x for wp之EaseActions——运动加速效果

在现实生活中有很多情况下，物体的运动都是带有加速度的运动。如果只是凭借cocos2d-x（wp）里的CCActionInstanse（瞬时动作的基类）和CCActionInterval（延时动作的基类）是无法达到“逼真”的现实运动效果的。

所以在cocos2d-x 里，有一个Ease系列

在Ease的方法里改变了运动的速度，但是并没有改变总体时间。如果整个的action持续5秒钟，那么整个的时间仍然会持续5秒钟。

这些action可以被分成3类：

In actions: action开始的时候加速

Out actions: action结束的时候加速

InOut actions: action开始，结束的时候加速

 

在Ease系列里的第一个参数为要加减速度的动作，第二个为加减的速率。

下面是个简单的例子：（m_grossini、m_tamara、m_kathia均为精灵）

CCActionInterval actionBy = CCJumpBy.actionWithDuration(2, new CCPoint(300, 100), 50, 4);
m_grossini.runAction(CCEaseIn.actionWithAction(actionBy, 2f));

 

还有一些特殊的缓冲：

1.指数缓冲（效果：如同指数函数一样，在开头或者结尾或者中间突然获得指数型的加速度）

CCEaseExponentialIn

CCEaseExponentialOut

CCEaseExponentialInOut

 

 

　　　　　　　CCActionInterval move = CCMoveBy.actionWithDuration(3, new CCPoint(350, 0));
            CCActionInterval move_back = move.reverse() as CCActionInterval;

            CCActionInterval move_ease_in = CCEaseExponentialIn.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_in_back = move_ease_in.reverse() as CCActionInterval;

            CCActionInterval move_ease_out = CCEaseExponentialOut.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_out_back = move_ease_out.reverse() as CCActionInterval;


            CCFiniteTimeAction seq1 = CCSequence.actions(move, move_back);
            CCFiniteTimeAction seq2 = CCSequence.actions(move_ease_in, move_ease_in_back);
            CCFiniteTimeAction seq3 = CCSequence.actions(move_ease_out, move_ease_out_back);


            m_grossini.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq1));
            m_tamara.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq2));
            m_kathia.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq3));

 

2.赛因缓冲（效果：可以理解为头尾较为平缓、中间为加速度恒定的匀变速运动）

CCEaseSineIn

CCEaseSineOut

CCEaseSineInOut

 

            CCActionInterval move = CCMoveBy.actionWithDuration(3, new CCPoint(350, 0));
            CCActionInterval move_back = move.reverse() as CCActionInterval;

            CCActionInterval move_ease_in = CCEaseSineIn.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_in_back = move_ease_in.reverse() as CCActionInterval;

            CCActionInterval move_ease_out = CCEaseSineOut.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_out_back = move_ease_out.reverse() as CCActionInterval;


            CCFiniteTimeAction seq1 = CCSequence.actions(move, move_back);
            CCFiniteTimeAction seq2 = CCSequence.actions(move_ease_in, move_ease_in_back);
            CCFiniteTimeAction seq3 = CCSequence.actions(move_ease_out, move_ease_out_back);


            m_grossini.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq1));
            m_tamara.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq2));
            m_kathia.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq3));

 

3.弹性缓冲（效果：类似于弹了一下一根绷紧的橡皮筋。其实这个效果看名字就知道了）

CCEaseElasticIn

CCEaseElasticOut

CCEaseElasticInOut

        CCActionInterval move = CCMoveBy.actionWithDuration(3, new CCPoint(350, 0));
            CCActionInterval move_back = move.reverse() as CCActionInterval;

            CCActionInterval move_ease_in = CCEaseElasticIn.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_in_back = move_ease_in.reverse() as CCActionInterval;

            CCActionInterval move_ease_out = CCEaseElasticOut.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_out_back = move_ease_out.reverse() as CCActionInterval;

            CCFiniteTimeAction seq1 = CCSequence.actions(move, move_back);
            CCFiniteTimeAction seq2 = CCSequence.actions(move_ease_in, move_ease_in_back);
            CCFiniteTimeAction seq3 = CCSequence.actions(move_ease_out, move_ease_out_back);

            m_grossini.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq1));
            m_tamara.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq2));
            m_kathia.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq3)); 

4.跳跃缓冲（效果：可以理解为一个球从空中落地之后在地上弹跳的情况）

CCEaseBounceIn

CCEaseBounceOut

CCEaseBounceInOut

CCActionInterval move = CCMoveBy.actionWithDuration(3, new CCPoint(350, 0));
            CCActionInterval move_back = move.reverse() as CCActionInterval;

            CCActionInterval move_ease_in = CCEaseBounceIn.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_in_back = move_ease_in.reverse() as CCActionInterval;

            CCActionInterval move_ease_out = CCEaseBounceOut.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_out_back = move_ease_out.reverse() as CCActionInterval;

            CCFiniteTimeAction seq1 = CCSequence.actions(move, move_back);
            CCFiniteTimeAction seq2 = CCSequence.actions(move_ease_in, move_ease_in_back);
            CCFiniteTimeAction seq3 = CCSequence.actions(move_ease_out, move_ease_out_back);

            m_grossini.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq1));
            m_tamara.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq2));
            m_kathia.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq3));

5.回震缓冲（效果：跟跳跃缓冲差不多，不过回震可以看成类似完全弹性碰撞的结果）

CCEaseBackIn

CCEaseBackOut

CCEaseBackInOut

            CCActionInterval move = CCMoveBy.actionWithDuration(3, new CCPoint(350, 0));
            CCActionInterval move_back = move.reverse() as CCActionInterval;

            CCActionInterval move_ease_in = CCEaseBackIn.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_in_back = move_ease_in.reverse() as CCActionInterval;

            CCActionInterval move_ease_out = CCEaseBackOut.actionWithAction((CCActionInterval)(move.copy()));
            CCActionInterval move_ease_out_back = move_ease_out.reverse() as CCActionInterval;

            CCFiniteTimeAction seq1 = CCSequence.actions(move, move_back);
            CCFiniteTimeAction seq2 = CCSequence.actions(move_ease_in, move_ease_in_back);
            CCFiniteTimeAction seq3 = CCSequence.actions(move_ease_out, move_ease_out_back);

            m_grossini.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq1));
            m_tamara.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq2));
            m_kathia.runAction(CCRepeatForever.actionWithAction((CCActionInterval)seq3));