Cocos2d。繞另一點旋轉點而不需要進行數學計算？

Question

我還沒有看到有關在指定點周圍旋轉的簡單示例。我想是這樣的，但它不工作：

//CCNode *node is declared 
//In a function of a subclass of CCSprite 
- (void)moveWithCicrlce 
{ 
anchorNode = [CCNode node]; 
anchorNode.position = ccpSub(self.position, circleCenter); 
anchorNode.anchorPoint = circleCenter; 
[anchorNode runAction:[CCRotateBy actionWithDuration:1 angle:90]]; 
[self runAction:[CCRepeatForever actionWithAction:[CCSequence actions:[CCCallFunc actionWithTarget:self selector:@selector(rotate)], [CCDelayTime actionWithDuration:0.1], nil]]]; 
} 

- (void)rotate 
{ 
self.position = ccpAdd(anchorNode.position, anchorNode.anchorPoint); 
} 

Answer 1

我的近似解：

@interface Bomb : NSObject { 
    CCSprite *center; 
} 

... 

@end 

和一些方法：

- (void)explode 
{ 
    BombBullet *bullet = [BombBullet spriteWithFile:@"explosion03.png"]; 
    [[[CCDirector sharedDirector] runningScene] addChild:bullet]; 

    center = [CCSprite spriteWithTexture:bullet.texture]; 
    center.position = explosionPoint; 
    center.anchorPoint = ccp(-0.5, -0.5); 
    center.visible = NO; 
    [[[CCDirector sharedDirector] runningScene] addChild:center]; 
    [center runAction:[CCRotateBy actionWithDuration:1 angle:360]]; 

    CCCallFunc *updateAction = [CCCallFuncN actionWithTarget:self selector:@selector(update:)]; 
    [bullet runAction:[CCRepeatForever actionWithAction:[CCSequence actions:updateAction, [CCDelayTime actionWithDuration:0.01], nil]]]; 
} 

- (void)update:(id)sender 
{ 
    BombBullet *bombBullet = (BombBullet *)sender; 
    bombBullet.rotation = center.rotation; 
    bombBullet.position = ccpAdd(center.position, center.anchorPointInPoints); 
    bombBullet.position = ccpAdd(bombBullet.position, ccp(-bombBullet.contentSize.width/2, -bombBullet.contentSize.height/2)); 
    bombBullet.position = ccpRotateByAngle(bombBullet.position, center.position, bombBullet.rotation); 
} 

當然我應該加精靈刪除。

Answer 2

下面是可以旋轉的節點（精靈等），圍繞某一點P（50,50）與100爲半徑（與P的距離） ：

CCNode* center = [CCNode node]; 
center.position = CGPointMake(50, 50); 
[self addChild:center]; 

// node to be rotated is added to center node 
CCSprite* rotateMe = [CCSprite spriteWithFile:@"image.png"]; 
[center addChild:rotateMe]; 

// offset rotateMe from center by 100 points to the right 
rotateMe.position = CGPointMake(100, 0); 

// perform rotation of rotateMe around center by rotating center 
id rotate = [CCRotateBy actionWithDuration:10 rotation:360]; 
[center runAction:rotate];