void HelloWorld::setCenterOfScreen(CCPoint p){	CCSize s = CCDirector::sharedDirector()->getWinSize();	int x = MAX(p.x, s.width / 2);	int y = MAX(p.y, s.height / 2);	x = min(x, map->getMapSize().width * map->getTileSize().width - s.width/2);	y = min(y, map->getMapSize().height * map->getTileSize().height - s.height/2);	CCPoint goodPoint = ccp(x, y);	CCPoint centerOfScreen = ccp(s.width/2, s.height/2);	CCPoint diffence = ccpSub(centerOfScreen, goodPoint);	this->setPosition(diffence);}