Cocos2d-x (i): Understanding the entire game framework from the Hello World example

<span style= "font-family: Microsoft Ya-hei; Background-color:rgb (255, 255, 255); > First find main.cpp, program to enter </span>

A game that corresponds to a application,application responsibility is to manage the game lifecycle and set the default window to obtain platform and localized information. Application::getinstance ()->run () is the portal for the entire application.

int Apientry _tWinMain (hinstance hinstance,
                       hinstance hprevinstance,
                       LPTSTR lpcmdline,
                       int ncmdshow)
{
    unreferenced_parameter (hprevinstance);
    Unreferenced_parameter (lpcmdline);

    Create the application instance
    appdelegate app;
    Return Application::getinstance ()->run ();
}

Application usually does not create a Application object directly, but instead creates a appliction subclass: Appdelegate can see it in the game entry application::getinstance ()->run ()

    if (!applicationdidfinishlaunching ())
    {return
        0;
    }

In Applicationdidfinishlaunching, first initialize a Director and create an OpenGL es window for Director, and then create the first scene. General settings such as resolution, frame rate, resource search directory are all completed in applicationdidfinishlaunching.
A basic application starts with the initial chemical as follows:

BOOL Appdelegate::applicationdidfinishlaunching () {
    Auto Director = Director::getinstance ();
    Auto Glview = Director->getopenglview ();
    if (!glview) {
        Glview = glviewimpl::create ("Cpp Empty Test");
        Director->setopenglview (Glview);
    }

    Director->setanimationinterval (1.0/60);

    Auto scene = Helloworld::scene ();

    Director->runwithscene (scene);

    return true;
}

Now the operating system basically supports multitasking, when the player leaves the game, should suspend the game:

void Appdelegate::applicationdidenterbackground () {
    director::getinstance ()->stopanimation ();

}

When the player returns to the game, the game should be restored:

void Appdelegate::applicationwillenterforeground () {
    director::getinstance ()->startanimation ();

    If use Simpleaudioengine, it must resume here
    //Simpleaudioengine::sharedengine ()->resumebackgroundmusic ();
}

The frame rate Director->setanimationinterval (1.0/60) is set in the applicationdidfinishlaunching. The frame rate determines how the game cycle is updated at what intervals. Application::Run drive the game cycle, according to the frame rate set for the game's Cycle logic update, the following is the implementation of Application::Run

int Application::Run () {Pvrframeenablecontrolwindow (false);
    Main message Loop:large_integer nlast;

    Large_integer Nnow;

    QueryPerformanceCounter (&nlast);

    Initglcontextattrs ();
    Initialize instance and cocos2d.
    if (!applicationdidfinishlaunching ()) {return 0;
    Auto director = Director::getinstance ();

    Auto Glview = Director->getopenglview ();

    Retain Glview to avoid Glview being released in the while Loop Glview->retain ();
        while (!glview->windowshouldclose ()) {QueryPerformanceCounter (&nnow); if (Nnow.quadpart-nlast.quadpart > _animationinterval.quadpart) {nlast.quadpart = Nnow.quadpart
            
            -(nnow.quadpart% _animationinterval.quadpart);
            Director->mainloop ();
        Glview->pollevents ();
        else {sleep (1); }//Director should still do a cleanup if the window was closed manually.
        if (Glview->isopenglready ()) {director->end ();
        Director->mainloop ();
    Director = NULLPTR;
    } glview->release ();
return true; }

Mainloop defines a game loop for all events and Content Application::Run () after a loop, hibernate until the next update is idle, until the next cycle is updated.

In the applicationdidfinishlaunching, you can see

    Auto scene = Helloworld::scene ();
    Director->runwithscene (Scene);

Auto scene = Helloworld::scene (); Creates a scene

scene* Helloworld::scene ()
{
    //' Scene ' is a Autorelease object
    auto Scene = Scene::create ();
    
    ' Layer ' is a Autorelease object
    HelloWorld *layer = Helloworld::create ();

    Add layer as a child to scene
    Scene->addchild (layer);

    Return the scene return
    scene;
}

As you can see, creating a class calls the CREATE function, why not direct new Scene (), we open the CREATE function

scene* scene::create ()
{
    Scene *ret = new (Std::nothrow) Scene ();
    if (ret && ret->init ())
    {
        ret->autorelease ();
        return ret;
    }
    else
    {
        cc_safe_delete (ret);
        Return nullptr
    }
}

You can see that in the CREATE function, first the new object is called, then the object's Init method is invoked, and the modified object is added to the Cocos2d-x memory management and set to automatic release. In Cocos2d-x, objects are inherited from the ref base class, and the ref base class is primarily responsible for referencing technical management of objects. Declare an object pointer as a smart pointer with the Autorelease () method, but the smart pointers are not associated with an automatic variable alone, but are all joined in a autoreleasepool. Add the objects in the Autoreleasepool at the end of each frame to clean up. So, in Cocos2d-x, the lifecycle of a smart pointer ends at the end of the current frame, starting with the creation.
The initialization of a class is generally done in Init in Helloworld::init, and the work done has created a menu, a character tag and an elf. Director::getinstance ()->getvisiblesize () Gets the window size director::getinstance ()->getvisibleorigin () Gets the game coordinates, which defaults to the lower left corner ( 0,0) to create the code for the menu:

Auto Closeitem = menuitemimage::create (
                                        "Closenormal.png",
                                        "Closeselected.png",
                                        cc_callback_1 ( Helloworld::menuclosecallback,this));
    
    Closeitem->setposition (Origin + VEC2 (visiblesize)-VEC2 (Closeitem->getcontentsize ()/2));

    Create menu, it ' s an Autorelease object
    auto menu = Menu::create (Closeitem, nullptr);
    Menu->setposition (Vec2::zero);
    This->addchild (menu, 1);

Here is the use of pictures to create a menu, the default when the button picture is closenormal.png selected for Closeselected.png, and added a listener, the menu is clicked when the Menuclosecallback function is called. Using SetPosition to set the menu position, This->addchild (menu, 1) to place the menus into the layer of the scene, 1 for the priority of the display to create character labels and sprites (background pictures) are all using a similar method, first invoking create creation, Then use the setposition to set the position and add the layer through the addchild. After the initialization of the scene, Director->runwithscene (scene); Run the scene. The first scene of the game run using the Runwithscene method after the scene is run using Director->replacescene (Newscene) replaces the current scene. Program Run Effect: