cocos2d中两种移动的算法

在对cocos2d的sprite处理移动的过程中，通常用到的两种移动的算法：

假设这个CCNode是直接放在CCLayer上的

距离差法：

CGPoint curTouchPosUI = [touch locationInView:[touch view]];
CGPoint preTouchPosUI = [touch previousLocationInView:[touch view]];

CGPoint curTouchPosGL = [[CCDirector sharedDirector] convertToGL:curTouchPosUI];

CGPoint preTouchPosGL = [[CCDirector sharedDirector] convertToGL:preTouchPosUI];

CGPoint distancePos = ccpSub(curTouchPosGL,preTouchPosGL);

self.position=ccpAdd(self.position,distancePos);

点击法：

CGPoint touchPosUI = [touch locationInView:[touch view]];
CGPoint touchPosGL = [[CCDirector sharedDirector] convertToGL:touchPosUI];

CGPoint pos = ccp(touchPosGL.x -_touchBeginPosToSelfAnchorPointDistancePos.x,
                          touchPosGL.y - _touchBeginPosToSelfAnchorPointDistancePos.y);

self.position = pos;

其中 _touchBeginPosToSelfAnchorPointDistancePos = ccpSub(_touchBeginPos,self.position)
     
_touchBeginPos begin touch在物体上的坐标