cocos3.X 惯性滑动

1 主要思路

实现手指拖动地图后，手指离开地图后，地图距离会向着手指的方向移动一段距离：

1.在滑动中把每个点放入到容器中

2.滑动结束根据最后一个点与倒数第二点的设定x，y方向上的位移

3.根据摩擦系数，依次减小位移，直至小到一定程度

2 详细设计

2.1 给地图精灵绑定触摸监听

auto listener1 = EventListenerTouchOneByOne::create();//创建一个触摸监听
	listener1->setSwallowTouches(true); //设置是否想下传递触摸
	//通过 lambda 表达式 直接实现触摸事件的回掉方法
	listener1->onTouchBegan = [=](Touch* touch, Event* event){
		return onTouchBegan(touch, event);
	};
	listener1->onTouchMoved = [=](Touch* touch, Event* event){
		onTouchMoved(touch, event);
	};
	listener1->onTouchEnded = [=](Touch* touch, Event* event){
		onTouchEnded(touch, event);
	};
	_eventDispatcher->addEventListenerWithSceneGraphPriority(listener1, m_spr);

2.2触摸开始

bool  HelloWorld::onTouchBegan(Touch* touch, Event*  event)
{
	auto target = static_cast(event->getCurrentTarget());
	m_vecPot.clear();
	Point locationInNode = target->convertToNodeSpace(touch->getLocation());
	Size s = target->getContentSize();
	Rect rect = Rect(0, 0, s.width, s.height);

	if (rect.containsPoint(locationInNode))
	{
		log("sprite began... x = %f, y = %f", locationInNode.x, locationInNode.y);
		target->setOpacity(180);
		return true;
	}
	return false;
}

当按在精灵上时，返回true，表示能继续响应后面的move操作。

2.3触摸移动

void  HelloWorld::onTouchMoved(Touch* touch, Event*  event)
{
	m_bDrag = true;
	auto target = static_cast(event->getCurrentTarget());
	target->setPosition(target->getPosition() + touch->getDelta());
	Point locationInNode = target->convertToWorldSpace(touch->getLocation());
	m_vecPot.push_back(locationInNode);
}

移动时保存每个移动的点到m_vecPot容器中。

2.4触摸结束

void  HelloWorld::onTouchEnded(Touch* touch, Event*  event)
{
	auto target = static_cast(event->getCurrentTarget());
	target->setOpacity(255);
	if (m_bDrag == true)
	{
		m_bDrag = false;
		int iVecSize = m_vecPot.size();
		float fXspeed = m_vecPot[iVecSize - 1].x - m_vecPot[iVecSize - 2].x;
		float fYspeed = m_vecPot[iVecSize - 1].y - m_vecPot[iVecSize - 2].y;
		while (abs(fXspeed) > 0.1 || abs(fYspeed) > 0.1)
		{
			Point potNew = ccpAdd(target->getPosition(), Point(fXspeed, fYspeed));
			auto moveBy = MoveBy::create(0.1f, ccp(fXspeed, fYspeed));
			target->runAction(moveBy);
			fXspeed *= GfFriction;
			fYspeed *= GfFriction;
		}
	}
}

判断结束时，最后一个点与倒数第二点的位置差。当位置差绝对值大于一定量时，移动精灵，位置差再乘上摩擦系数，直到位置差小于这个一定量精灵将停止移动。

源码下载

http://download.csdn.net/detail/luoyikun/9119487