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

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();
}