Cocos2dx_背景层循环滚动

function MovieLayer:update(dt)

	local posY1 = self.m_bg1:getPositionY()
	local posY2 = self.m_bg2:getPositionY()
	local speed = 3

	posY1 = posY1 + speed
	posY2 = posY2 + speed
	local height = winSize.height

	if posY1 > height * 1.5 then
		posY2 = height * 0.5
		posY1 = -height * 0.5
	end

	if posY2 > height * 1.5 then
		posY1 = height * 0.5
		posY2 = -height * 0.5
	end

	self.m_bg1:setPositionY(posY1)
	self.m_bg2:setPositionY(posY2)
end

function MovieLayer:init()
    local m_bg1 = cc.Sprite:create("game_bg1.png")
    m_bg1:setPosition(cc.p(winSize.width/2,winSize.height/2))
    self:addChild(m_bg1)
    self.m_bg1 = m_bg1

    local m_bg2 = cc.Sprite:create("game_bg1.png")
    m_bg2:setPosition(cc.p(winSize.width/2,-winSize.height/2))
    self:addChild(m_bg2)
    self.m_bg2 = m_bg2

    local function updateFunc(dt)
    	self:update(dt)
    end

    if self.updateHandler == nil then
	    self.updateHandler = scheduler:scheduleScriptFunc(updateFunc,false)
    end
end