Hello.lua注释

这个注释cocos2d-x给我们写的hello.lua

-- for CCLuaEngine traceback 输出绑定执行函数发生错误的信息
function __G__TRACKBACK__(msg)
    print("----------------------------------------")
    print("LUA ERROR: " .. tostring(msg) .. "\n")
    print(debug.traceback())
    print("----------------------------------------")
end

local function main()
    -- avoid memory leak 设置脚本内存回收参数 避免内存泄露
    collectgarbage("setpause", 100)
    collectgarbage("setstepmul", 5000)
	
    -- 就是local function cclog(...) 定义局部Log函数
    local cclog = function(...) 
        print(string.format(...))
    end

	--类似c++的include,会检查是否重复引入
    require "hello2"
    cclog("result is " .. myadd(3, 5))

    ---------------
	-- 读取可视的区域
    local visibleSize = CCDirector:sharedDirector():getVisibleSize()
    local origin = CCDirector:sharedDirector():getVisibleOrigin()

    -- add the moving dog 创建一个小松鼠
    local function creatDog()
        local frameWidth = 105
        local frameHeight = 95

        -- create dog animate
        local textureDog = CCTextureCache:sharedTextureCache():addImage("dog.png")
		-- 读取纹理的区域大小
        local rect = CCRectMake(0, 0, frameWidth, frameHeight)
		-- 读取纹理
        local frame0 = CCSpriteFrame:createWithTexture(textureDog, rect)
        rect = CCRectMake(frameWidth, 0, frameWidth, frameHeight)
        local frame1 = CCSpriteFrame:createWithTexture(textureDog, rect)

        local spriteDog = CCSprite:createWithSpriteFrame(frame0)
        spriteDog.isPaused = false
        spriteDog:setPosition(origin.x, origin.y + visibleSize.height / 4 * 3)

        local animFrames = CCArray:create()

        animFrames:addObject(frame0)
        animFrames:addObject(frame1)

        local animation = CCAnimation:createWithSpriteFrames(animFrames, 0.5)
        local animate = CCAnimate:create(animation);
		-- 初始状态是frame0
        spriteDog:runAction(CCRepeatForever:create(animate))

        -- moving dog at every frame。这个是来决定松鼠往右走
        local function tick()
            if spriteDog.isPaused then return end
            local x, y = spriteDog:getPosition()
            if x > origin.x + visibleSize.width then
                x = origin.x
            else
                x = x + 1
            end

            spriteDog:setPositionX(x)
        end
		-- 生成一个schedule，每帧执行tick函数
        CCDirector:sharedDirector():getScheduler():scheduleScriptFunc(tick, 0, false)

        return spriteDog
    end

    -- create farm
    local function createLayerFarm()
        local layerFarm = CCLayer:create()

        -- add in farm background   添加背景
        local bg = CCSprite:create("farm.jpg")
        bg:setPosition(origin.x + visibleSize.width / 2 + 80, origin.y + visibleSize.height / 2)
        layerFarm:addChild(bg)

        -- add land sprite   添加草地
        for i = 0, 3 do
            for j = 0, 1 do
                local spriteLand = CCSprite:create("land.png")
                spriteLand:setPosition(200 + j * 180 - i % 2 * 90, 10 + i * 95 / 2)
                layerFarm:addChild(spriteLand)
            end
        end

        -- add crop          添加植物
        local frameCrop = CCSpriteFrame:create("crop.png", CCRectMake(0, 0, 105, 95))
        for i = 0, 3 do
            for j = 0, 1 do
                local spriteCrop = CCSprite:createWithSpriteFrame(frameCrop);
                spriteCrop:setPosition(10 + 200 + j * 180 - i % 2 * 90, 30 + 10 + i * 95 / 2)
                layerFarm:addChild(spriteCrop)
            end
        end

        -- add moving dog 添加移动的狗
        local spriteDog = creatDog()
        layerFarm:addChild(spriteDog)

        -- handing touch events 手指触摸事件的处理
        local touchBeginPoint = nil
		-- 如果有安到
        local function onTouchBegan(x, y)
            cclog("onTouchBegan: %0.2f, %0.2f", x, y) 
            touchBeginPoint = {x = x, y = y} -- 记住点击的位置
            spriteDog.isPaused = true --将松鼠暂停
            -- CCTOUCHBEGAN event must return true  这里要return true,否则后面将无法运行
            return true
        end

        local function onTouchMoved(x, y) -- 结束的位置减去初始的位置就是移动的位置
            -- cclog("onTouchMoved: %0.2f, %0.2f", x, y)
            if touchBeginPoint then -- 这个变量是在上面声明的
			-- 将整个农场层拖动，因为之前已经将农场里面所有对象加入在layerFarm 
                local cx, cy = layerFarm:getPosition()
                layerFarm:setPosition(cx + x - touchBeginPoint.x,
                                      cy + y - touchBeginPoint.y)
                touchBeginPoint = {x = x, y = y}
            end
        end
		-- 手指离开
        local function onTouchEnded(x, y)
            cclog("onTouchEnded: %0.2f, %0.2f", x, y)
            touchBeginPoint = nil -- 数据清空
            spriteDog.isPaused = false -- 松鼠显示出来
        end

        local function onTouch(eventType, x, y)
            if eventType == CCTOUCHBEGAN then
                return onTouchBegan(x, y)
            elseif eventType == CCTOUCHMOVED then
                return onTouchMoved(x, y)
            else
                return onTouchEnded(x, y)
            end
        end
		-- 设置监听器
        layerFarm:registerScriptTouchHandler(onTouch)
        layerFarm:setTouchEnabled(true) 

        return layerFarm
    end


    -- create menu 建立目录
    local function createLayerMenu()
        local layerMenu = CCLayer:create()

        local menuPopup, menuTools, effectID

        local function menuCallbackClosePopup()
            -- stop test sound effect 停止音乐
            SimpleAudioEngine:sharedEngine():stopEffect(effectID)
            menuPopup:setVisible(false)
        end

        local function menuCallbackOpenPopup()
            -- loop test sound effect
            local effectPath = CCFileUtils:sharedFileUtils():fullPathFromRelativePath("effect1.wav")
            effectID = SimpleAudioEngine:sharedEngine():playEffect(effectPath)
            menuPopup:setVisible(true)
        end

        -- add a popup menu 创建弹出的菜单面板
        local menuPopupItem = CCMenuItemImage:create("menu2.png", "menu2.png")
        menuPopupItem:setPosition(0, 0)
        menuPopupItem:registerScriptTapHandler(menuCallbackClosePopup)
        menuPopup = CCMenu:createWithItem(menuPopupItem)
        menuPopup:setPosition(origin.x + visibleSize.width / 2, origin.y + visibleSize.height / 2)
        menuPopup:setVisible(false)
        layerMenu:addChild(menuPopup)

        -- add the left-bottom "tools" menu to invoke menuPopup 这里是建立工具按钮
        local menuToolsItem = CCMenuItemImage:create("menu1.png", "menu1.png")
        menuToolsItem:setPosition(0, 0)
        menuToolsItem:registerScriptTapHandler(menuCallbackOpenPopup) -- 响应函数
        menuTools = CCMenu:createWithItem(menuToolsItem)
        local itemWidth = menuToolsItem:getContentSize().width
        local itemHeight = menuToolsItem:getContentSize().height
        menuTools:setPosition(origin.x + itemWidth/2, origin.y + itemHeight/2)
        layerMenu:addChild(menuTools)

        return layerMenu
    end

    -- play background music, preload effect

    -- uncomment below for the BlackBerry version
    -- local bgMusicPath = CCFileUtils:sharedFileUtils():fullPathFromRelativePath("background.ogg")
    local bgMusicPath = CCFileUtils:sharedFileUtils():fullPathFromRelativePath("background.mp3")
    SimpleAudioEngine:sharedEngine():playBackgroundMusic(bgMusicPath, true)
    local effectPath = CCFileUtils:sharedFileUtils():fullPathFromRelativePath("effect1.wav")
    SimpleAudioEngine:sharedEngine():preloadEffect(effectPath)

    -- run
    local sceneGame = CCScene:create()
    sceneGame:addChild(createLayerFarm())
    sceneGame:addChild(createLayerMenu())
    CCDirector:sharedDirector():runWithScene(sceneGame)
end

xpcall(main, __G__TRACKBACK__)
--[[ xpcall( 调用函数, 错误捕获函数 ); 
lua提供了xpcall来捕获异常
xpcall接受两个参数:调用函数、错误处理函数。 
当错误发生时,Lua会在栈释放以前调用错误处理函数,
因此可以使用debug库收集错误相关信息。
两个常用的debug处理函数:debug.debug和debug.traceback 
前者给出Lua的提示符,你可以自己动手察看错误发生时的情况;
后者通过traceback创建更多的错误信息,
也是控制台解释器用来构建错误信息的函数。
--]]