cocos2d－基本概念(3)-Actions:Ease缓冲动作

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The Ease actions alter the linearity of the time.

例如它们可以对inner的action进行加速或者是减速。 

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

For more information about easing or tweening actions, visit any of these pages:

• http://hosted.zeh.com.br/tweener/docs/en-us/misc/transitions.html
• http://www.robertpenner.com/easing/easing_demo.html

这些内部的action是按着如下进行加速的:

-(void) update:(ccTime) t{   [inner update: powf(t,rate)];}

rate 这个参数就是增加的速率

以下举了几个例子说明的分别的动作的开始，结束，和开始或者结束的时候加速。 

Example:

// acceleration at the beginning
        id action = [MoveTo actionWithDuration:2 position:ccp(100,100)];
 id ease = [EaseIn actionWithAction:action rate:2];
 [sprite runAction: ease];
 
 // acceleration at the end
 id action = [MoveTo actionWithDuration:2 position:ccp(100,100)];
 id ease = [EaseIn actionWithAction:action rate:2];
 [sprite runAction: ease];
 
 // acceleration at the beginning / end
 id action = [MoveTo actionWithDuration:2 position:ccp(100,100)];
 id ease = [EaseInOut actionWithAction:action rate:2];
 [sprite runAction: ease];

• EaseExponentialIn
• EaseExponentialOut
• EaseExponentialInOut

• EaseSineIn
• EaseSineOut
• EaseSineInOut

接下来的几个Ease的action，在最新版本的cocos2d里面找不到了，貌似已经干掉了。不理解了。。可以我从xcode拿出来的code，就知道了，以下的这几个关键字已经不变色了。。

就剩下一个rate的了。

[EaseRateAction actionWithAction:<#(IntervalAction *)action#> rate:<#(float)rate#>]; 

These actions alters the time simulating an elastic. Elastic actions will use time values greater than 1 and lower than 0, so the inner action should be prepared to handle this special values.

Also some values will be triggered more than once (this function is not bijective), so again, the inner action should be prepared to handle this values. Simple actions like MoveBy, ScaleBy, RotateBy work OK with EaseElastic actions, but the Sequence or Spawnactions might have unexpected results.

Available since v0.8.2

Available elastic actions:

• EaseElasticIn
• EaseElasticOut
• EaseElasticInOut

Examples:

 
 // 'period' is how elastic is the action.
 // recommended values: between 0.3 and 0.45
 
 // Elastic at the beginning
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseElasticIn actionWithAction:move period:0.3f];
 [sprite runAction: action];
 
 // Elastic at the end
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseElasticOut actionWithAction:move period:0.3f];
 [sprite runAction: action];
 
 // Elastic at the beginning and at the end
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseElasticInOut actionWithAction:move period:0.3f];
 [sprite runAction: action];

EaseBounce actions simulates a bouncing effect.

Some time values will be triggered more than once (this function is not bijective), so the inner action should be prepared to handle this values. Simple actions like MoveBy, ScaleBy, RotateBy work OK with EaseBounce actions, but the Sequence or Spawn actions might have unexpected results.

Available since v0.8.2

Available bounce actions:

• EaseBounceIn
• EaseBounceOut
• EaseBounceInOut

Examples:

 
 // Bounce at the beginning
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseBounceIn actionWithAction:move];
 [sprite runAction: action];
 
 // Bounce at the end
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseBounceOut actionWithAction:move];
 [sprite runAction: action];
 
 // Bounce at the beginning and at the end
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseBounceInOut actionWithAction:move];
 [sprite runAction: action];

Some time values will be triggered more than once (this function is not bijective), so the inner action should be prepared to handle this values. Simple actions like MoveBy, ScaleBy, RotateBy work OK with EaseBack actions, but the Sequence or Spawn actions might have unexpected results.

Available since v0.8.2

Available bounce actions:

• EaseBackIn
• EaseBackOut
• EaseBackInOut

Examples:

 
 // Back at the beginning
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseBackIn actionWithAction:move];
 [sprite runAction: action];
 
 // Back at the end
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseBackOut actionWithAction:move];
 [sprite runAction: action];
 
 // Back at the beginning and at the end
 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [EaseBackInOut actionWithAction:move];
 [sprite runAction: action];

The Speed action modifies the duration of the inner action.

 id move = [MoveBy actionWithDuration:3 position:ccp(350,0)];
 id action = [Speed actionWithAction: move speed:1.0f];   // no speed modification
 
 // but you can modify the speed later
 [action setSpeed: 2.5f]; // speed is 2.5 faster
 
 [action setSpeed: 0.5f]; // speed is 0.5 faster (it means 2 times slower)