cocos2dx中用动作实现背景无限滚动

cocos2dx-3.1.5中用动作实现背景滚动，cocos2dx都可以使用的

用到的动作其实很简单

1. MoveBy 因为有反动作
2. TargetedAction 给指定目标1个动作
3. Spawn 同时执行
4. Sequence 动作按照顺序执行
5. RepeatForever 一直重复执行

如果用定时器，会有画面抖动，因为每帧执行的时间不一样，而我们用动作实现背景滚动只需要关注移动的时间，不需要关注每帧偏移的像素是多少。

头文件

#pragma once#include "GameSceneManager.h"#define DEF_ROLL_SPEDD 8/*背景滚动*/class BackgroundLayer : public Layer{public:    virtual bool init();    CREATE_FUNC(BackgroundLayer);    Scale9Sprite* createBackGround(Vec2 pos);    // 默认背景滚动图片    static int currBgImageIndex;    // 滚动速度，值越小速度越快    static int rollTime;    void startRollBg();    void stop();    bool isFastRoll = false;};

cpp文件

#include "BackgroundLayer.h"int BackgroundLayer::rollTime = DEF_ROLL_SPEDD;int BackgroundLayer::currBgImageIndex = 1;bool BackgroundLayer::init(){    if (!Layer::init())    {        return false;    }    startRollBg();    return true;}Scale9Sprite* BackgroundLayer::createBackGround(Vec2 pos){    auto background = Scale9Sprite::create(StringUtils::format(BACKGROUND_IMG_NAME, currBgImageIndex));    background->setScale9Enabled(true);    background->setContentSize(winSize);    background->setPosition(pos);    background->setAnchorPoint(Vec2::ZERO);    this->addChild(background);    return background;}void BackgroundLayer::startRollBg(){    // 创建2张背景图    Scale9Sprite* bg = createBackGround(Vec2::ZERO);    Scale9Sprite* bg2 = createBackGround(Vec2(0, winSize.height));    // 滚动动作    auto mt = MoveBy::create(rollTime, Vec2(0, -winSize.height));    auto ta = TargetedAction::create(bg, mt);    auto ta2 = TargetedAction::create(bg2, mt->clone());    // 同时执行    auto spawn = Spawn::createWithTwoActions(ta, ta2);    // 重复执行，设定位置    auto rf = RepeatForever::create(Sequence::createWithTwoActions(spawn, CallFunc::create([=]()    {        //this->stopAllActions();        bg->setPositionY(0);        bg2->setPositionY(winSize.height);        //log("----");    })));    // 当前Layer执行这个Action    this->runAction(rf);}void BackgroundLayer::stop(){    this->stopAllActions();}