3、cocos2d-Lua的运行流程与场景

发布时间：2020-12-14 21:43:11 所属栏目：百科来源：网络整理

导读：打开工程根目录下的配置文件config.json： { "init_cfg" : { "isLandscape" : true , "isWindowTop" : false ,122)"> "name" : "redDefense" ,122)"> "width" : 1920 ,122)"> "height" : 1080 ,122)"> "entry" : "src/main.lua" ,122)"> "consolePort" : 605

打开工程根目录下的配置文件config.json：

{
"init_cfg": {
"isLandscape": true,
"isWindowTop": false,122)">"name": "redDefense",122)">"width": 1920,122)">"height": 1080,122)">"entry": "src/main.lua",122)">"consolePort": 6050,122)">"uploadPort": 6060,122)">"debugPort": 10000,122)">"forwardConsolePort": 10089,122)">"forwardUploadPort": 10091
},122)">"simulator_screen_size": [
    {
"title": "iPhone 3Gs (480x320)",255)">480,255)">320
    {
"iPhone 4 (960x640)",255)">960,255)">640
"iPhone 5 (1136x640)",255)">1136,0)">"iPad (1024x768)",255)">1024,255)">768
"iPad Retina (2048x1536)",255)">2048,255)">1536
"Android (800x480)",255)">800,255)">480
"Android (854x480)",255)">854,0)">"Android (1280x720)",255)">1280,255)">720
"Android (1920x1080)",255)">1080
}
  ]
}

可以看到 "entry": "src/main.lua",也就是说入口文件是main.lua，进而打开main.lua：

cc.FileUtils:getInstance():setPopupNotify(false)
addSearchPath("src/")
"res/")

require "config"
"cocos.init"

local function main()
require("app.MyApp"):create():run()
end

local status,msg = xpcall(main,__G__TRACKBACK__)
if not status then
print(msg)
end

执行main函数，main函数里加载MyApp创建并运行，进而打开MyApp.lua：

MyApp = class("MyApp",43)">load("mvc").AppBase)

function MyApp:onCreate()
math.randomseed(os.time())
return MyApp

这里就有点看头，MyApp仅仅是继承自AppBase，onCreate函数只是初始化了下随机数种子，也就意味着更多的操作在AppBase中，我们打开分析：

AppBase = "AppBase")

AppBase:ctor(configs)
self.configs_ = {
viewsRoot  = "app.views",
modelsRoot = "app.models",43)">defaultSceneName = "MainScene",
    }

for k,153)">v in pairs(configs or {}) do
configs_[k] = v
 if type(configs_.viewsRoot) ~= "table" viewsRoot = {viewsRoot}
modelsRoot) ~= modelsRoot = {modelsRoot}
DEBUG > 1 dump(configs_,0)">"AppBase configs")
CC_SHOW_FPS Director:setDisplayStats(true)
-- event
self:onCreate()
run(initSceneName)
initSceneName = initSceneName or defaultSceneName
enterScene(initSceneName)
enterScene(sceneName,transition,255)">time,255)">more)
view = createView(sceneName)
view:showWithScene(view
createView(name)
_,153)">root ipairs(viewsRoot)  local packageName = string.format("%s.%s",153)">root,153)">view = function()
return require(packageName)
end,128)">function(msg)
if not find(msg,0)">"'%s' not found:",packageName)) "load view error: ",128)"> end)
t = type(view)
if and (t == or "userdata") return view:create(self,name)
 end
error("AppBase:createView() - not found view "%s" in search paths "%s"",
name,0)">table.concat(viewsRoot,0)">",")),255)">0)
AppBase

在前面的分析中知道main.lua是执行的是App的run函数，作为基类的AppBase，当然也要被调用run函数，因此直接看run函数：主要是创建并进入场景initSceneName，如果run的参数没有指定开始的场景则使用默认场景defaultSceneName，默认场景在构造函数的时候被初始化为MainScene，也就是说场景默认将从MainScene开始。

如果给run指定了场景名(字符串)，那么项目启动后会直接进入该场景，这点有个好处是如果要调试设计某场景可以直接从这个场景进入，不必从其他场景进入了。也就是在main.lua中这么调用即可：

run('PlayScene')
end

那么项目启动后会直接进入PlayScene场景，而不再是默认的MainScene场景。

我们现在不做改动，仍然接着默认流程分析， MainScene为主场景，创建并显示一张背景图，创建显示一个“Play”按钮，按钮的点击事件是进入PlayScene场景。

local MainScene = class ( "MainScene" , cc . load "mvc" ). ViewBase )

MainScene:-- add background image
display.newSprite("MainSceneBg.jpg")
        :move(center)
        :addTo(self)

-- add play button
playButton = MenuItemImage:create("PlayButton.png",0)">"PlayButton.png")
        :onClicked(function()
self:getApp():enterScene("PlayScene")
end)
Menu:playButton)
        :cx,43)">cy - 200)
        :self)
MainScene

PlayScene场景：

PlayScene = "PlayScene",43)">ViewBase)

GameView = import(".GameView")

PlayScene:-- create game view and add it to stage
gameView_ = GameView:create()
        :addEventListener(GameView.events.PLAYER_DEAD_EVENT,0)">handler(self,43)">onPlayerDead))
        :start()
        :onPlayerDead(event)
-- add game over text
text = "You killed %d bugs",43)">gameView_:getKills())
Label:createWithSystemFont(text,0)">"Arial",255)">96)
        :align(CENTER,128)">-- add exit button
exitButton = "ExitButton.png",0)">"ExitButton.png")
        :"MainScene")
exitButton)
        :PlayScene

PlayScene场景创建游戏逻辑视图GameView并调用start函数开始游戏，绑定了一个游戏结束的事件，这个事件会在GameView中在触发游戏结束逻辑时发生，PlayScene由于绑定了该事件，则会在游戏结束时调用其绑定的回调事件，以显示战绩和分数，显示一个退出按钮，退出按钮事件为进入MainScene场景。

至此，场景的切换已经很清晰了，那么主要的游戏逻辑便是在GameView中了。

打开工程根目录下的配置文件config.json：

"init_cfg": {
"isLandscape": true,122); font-weight:bold">"isWindowTop": false,122); font-weight:bold">"name": "redDefense",122); font-weight:bold">"width": "height": "entry": "src/main.lua",122); font-weight:bold">"consolePort": "uploadPort": "debugPort": "forwardConsolePort": "forwardUploadPort": "simulator_screen_size": [
    {
"title": "iPhone 3Gs (480x320)",0); font-weight:bold">"iPhone 4 (960x640)",0); font-weight:bold">"iPhone 5 (1136x640)",0); font-weight:bold">"iPad (1024x768)",0); font-weight:bold">"iPad Retina (2048x1536)",0); font-weight:bold">"Android (800x480)",0); font-weight:bold">"Android (854x480)",0); font-weight:bold">"Android (1280x720)",0); font-weight:bold">"Android (1920x1080)",255)">}
  ]
}

可以看到 "entry": "src/main.lua",也就是说入口文件是main.lua，进而打开main.lua：

false)
"src/")
"res/")

"config"
"cocos.init"

local function "app.MyApp"):end

local if not then
end

执行main函数，main函数里加载MyApp创建并运行，进而打开MyApp.lua：

"MyApp",0); font-weight:bold">"mvc").function return MyApp

这里就有点看头，MyApp仅仅是继承自AppBase，onCreate函数只是初始化了下随机数种子，也就意味着更多的操作在AppBase中，我们打开分析：

"AppBase")

"app.views",0); font-weight:bold">"app.models",0); font-weight:bold">"MainScene",128); font-weight:bold">for in or {}) do
    if "table" "AppBase configs")
true)
-- event
or         local "%s.%s",128); font-weight:bold">function()
return require(packageName)
end,128); font-weight:bold">function(if not "'%s' not found:",packageName)) "load view error: ",128); font-weight:bold">        end)
if and (or "userdata") return view:create(self,name)
    end
"AppBase:createView() - not found view "%s" in search paths "%s"",0); font-weight:bold">",")),153)">AppBase

'PlayScene')
end

那么项目启动后会直接进入PlayScene场景，而不再是默认的MainScene场景。

local MainScene = class ( "MainScene" cc . load "mvc" ). ViewBase )

-- add background image
"MainSceneBg.jpg")
        :-- add play button
"PlayButton.png",0); font-weight:bold">"PlayButton.png")
        :function()
self:"PlayScene")
end)
MainScene

PlayScene场景：

"PlayScene",0); font-weight:bold">".GameView")

-- create game view and add it to stage
gameView_ = GameView:addEventListener(GameView.-- add game over text
"You killed %d bugs",0); font-weight:bold">"Arial",128); font-style:italic">-- add exit button
"ExitButton.png",0); font-weight:bold">"ExitButton.png")
        :"MainScene")
PlayScene

至此，场景的切换已经很清晰了，那么主要的游戏逻辑便是在GameView中了。

（编辑：李大同）

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