cocos3.X 惯性滑动

雨点打透心脏的1/2处 2022-08-08 15:50 144阅读 0赞

## 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<Sprite*>(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<Sprite*>(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<Sprite*>(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][http_download.csdn.net_detail_luoyikun_9119487]

[http_download.csdn.net_detail_luoyikun_9119487]: http://download.csdn.net/detail/luoyikun/9119487