Android cocos2dx游戏开发——示例程序HelloCpp源码分析

最新推荐文章于 2016-06-21 03:28:00 发布

原创最新推荐文章于 2016-06-21 03:28:00 发布 · 1.9k 阅读

CC 4.0 BY-SA版权

本文深入分析了Android平台上使用Cocos2dx进行游戏开发的HelloCpp示例程序，从HelloCpp.java开始，探讨了Activity的创建、Cocos2dxActivity的初始化过程，特别是GLSurfaceView和Cocos2dxRenderer的角色。文章还介绍了Cocos2dxGLSurfaceView如何作为游戏画面的关键View，并讲解了如何通过Cocos2dxRenderer的onSurfaceCreated和onDrawFrame方法进行渲染。

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本文通过分析cocos2dx提供的示例程序HelloCpp来分析cocos2dx的启动过程。

我们从HelloCpp.java开始：

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package org.cocos2dx.hellocpp;
import org.cocos2dx.lib.Cocos2dxActivity;
import android.os.Bundle;
public class HelloCpp extends Cocos2dxActivity{
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
}
static {
System.loadLibrary("hellocpp");
}
}

package org.cocos2dx.hellocpp;

import org.cocos2dx.lib.Cocos2dxActivity;

import android.os.Bundle;

public class HelloCpp extends Cocos2dxActivity{

	protected void onCreate(Bundle savedInstanceState){
		super.onCreate(savedInstanceState);
	}
	
    static {
         System.loadLibrary("hellocpp");
    }
}

HelloCpp是一个Activity，首先会执行静态代码块，加载libhellocpp.so库，然后就是执行onCreate方法，这里调用了父类的onCreate方法。我们看看Cocos2dxActivity的onCreate方法，该类在cocos2dx的库工程libcocos2dx中：

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@Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
sContext = this;
this.mHandler = new Cocos2dxHandler(this);
this.init();
Cocos2dxHelper.init(this, this);
}

@Override
	protected void onCreate(final Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		sContext = this;
    	this.mHandler = new Cocos2dxHandler(this);

    	this.init();

		Cocos2dxHelper.init(this, this);
	}

这里主要是执行初始化过程，Cocos2dxHandler主要处理显示Dialog的消息，Cocos2dxHelper是个辅助类，我们主要看init()方法：

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public void init() {
// FrameLayout
ViewGroup.LayoutParams framelayout_params =
new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT);
FrameLayout framelayout = new FrameLayout(this);
framelayout.setLayoutParams(framelayout_params);
// Cocos2dxEditText layout
ViewGroup.LayoutParams edittext_layout_params =
new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
Cocos2dxEditText edittext = new Cocos2dxEditText(this);
edittext.setLayoutParams(edittext_layout_params);
// ...add to FrameLayout
framelayout.addView(edittext);
// Cocos2dxGLSurfaceView
this.mGLSurfaceView = this.onCreateView();
// ...add to FrameLayout
framelayout.addView(this.mGLSurfaceView);
// Switch to supported OpenGL (ARGB888) mode on emulator
if (isAndroidEmulator())
this.mGLSurfaceView.setEGLConfigChooser(8 , 8, 8, 8, 16, 0);
this.mGLSurfaceView.setCocos2dxRenderer(new Cocos2dxRenderer());
this.mGLSurfaceView.setCocos2dxEditText(edittext);
// Set framelayout as the content view
setContentView(framelayout);
}

public void init() {
		
    	// FrameLayout
        ViewGroup.LayoutParams framelayout_params =
            new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
                                       ViewGroup.LayoutParams.FILL_PARENT);
        FrameLayout framelayout = new FrameLayout(this);
        framelayout.setLayoutParams(framelayout_params);

        // Cocos2dxEditText layout
        ViewGroup.LayoutParams edittext_layout_params =
            new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
                                       ViewGroup.LayoutParams.WRAP_CONTENT);
        Cocos2dxEditText edittext = new Cocos2dxEditText(this);
        edittext.setLayoutParams(edittext_layout_params);

        // ...add to FrameLayout
        framelayout.addView(edittext);

        // Cocos2dxGLSurfaceView
        this.mGLSurfaceView = this.onCreateView();

        // ...add to FrameLayout
        framelayout.addView(this.mGLSurfaceView);

        // Switch to supported OpenGL (ARGB888) mode on emulator
        if (isAndroidEmulator())
           this.mGLSurfaceView.setEGLConfigChooser(8 , 8, 8, 8, 16, 0);

        this.mGLSurfaceView.setCocos2dxRenderer(new Cocos2dxRenderer());
        this.mGLSurfaceView.setCocos2dxEditText(edittext);

        // Set framelayout as the content view
		setContentView(framelayout);
	}

这里就是为Activity绑定View Hierarchy，大家做Android开发的对着一定很熟悉。View Hierarchy的根View是个FrameLayout，FrameLayout又包含一个EditText和一个GLSurfaceView，这个GLSurfaceView就是cocos引擎用来绘制游戏画面的关键View，我们来详细分析一下它。首先看一下Cocos2dxActivity的onCreateView方法：

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public Cocos2dxGLSurfaceView onCreateView() {
return new Cocos2dxGLSurfaceView(this);
}

public Cocos2dxGLSurfaceView onCreateView() {
    	return new Cocos2dxGLSurfaceView(this);
    }

该方法就是新建一个Cocos2dxGLSurfaceView，Cocos2dxGLSurfaceView又继承于GLSurfaceView。我们都知道GLSurfaceView的核心就是Renderer，初始化时会调用Renderer的onSurfaceCreated方法，每一帧的绘制是通过调用Renderer的onDrawFrame方法。Cocos2dxGLSurfaceView的Renderer是一个Cocos2dxRenderer对象，我们先来看Cocos2dxRenderer对象的onSurfaceCreated方法：

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@Override
public void onSurfaceCreated(final GL10 pGL10, final EGLConfig pEGLConfig) {
Cocos2dxRenderer.nativeInit(this.mScreenWidth, this.mScreenHeight);
this.mLastTickInNanoSeconds = System.nanoTime();
}

@Override
	public void onSurfaceCreated(final GL10 pGL10, final EGLConfig pEGLConfig) {
		Cocos2dxRenderer.nativeInit(this.mScreenWidth, this.mScreenHeight);
		this.mLastTickInNanoSeconds = System.nanoTime();
	}

这里调用了一个本地方法nativeInit(final int pWidth, final int pHeight)，本地方法的实现在jni/hellocpp/main.cpp中实现的：

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void Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeInit(JNIEnv* env, jobject thiz, jint w, jint h)
{
if (!CCDirector::sharedDirector()->getOpenGLView())
{
CCEGLView *view = CCEGLView::sharedOpenGLView();
view->setFrameSize(w, h);
AppDelegate *pAppDelegate = new AppDelegate();
CCApplication::sharedApplication()->run();
}
else
{
......
}
}

void Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeInit(JNIEnv*  env, jobject thiz, jint w, jint h)
{
    if (!CCDirector::sharedDirector()->getOpenGLView())
    {
        CCEGLView *view = CCEGLView::sharedOpenGLView();
        view->setFrameSize(w, h);

        AppDelegate *pAppDelegate = new AppDelegate();
        CCApplication::sharedApplication()->run();
    }
    else
    {
        ...... 
    }
}

CCDirector是游戏的导演类，一个游戏只有一个导演类用来控制和管理场景。CCDirector::sharedDirector()是个静态方法，用来获取导演类的单例对象：

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CCDirector* CCDirector::sharedDirector(void)
{
if (!s_SharedDirector)
{
s_SharedDirector = new CCDisplayLinkDirector();
s_SharedDirector->init();
}
return s_SharedDirector;
}

CCDirector* CCDirector::sharedDirector(void)
{
    if (!s_SharedDirector)
    {
        s_SharedDirector = new CCDisplayLinkDirector();
        s_SharedDirector->init();
    }

    return s_SharedDirector;
}

CCCCDisplayLinkDirector是CCDirector的子类。我们再回到nativeinit方法中，获取到导演类的单例对象后又调用了它的getOpenGLView()方法：

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inline CCEGLView* getOpenGLView(void) { return m_pobOpenGLView; }

inline CCEGLView* getOpenGLView(void) { return m_pobOpenGLView; }

该方法返回用于游戏绘制的CCEGLView，在Android平台下，这个CCEGLView其实没有什么作用，因为游戏都是绘制在Cocos2dxGLSurfaceView上的。由于我们是初始化过程，所以此时m_pobOpenGLView为null，所以if (!CCDirector::sharedDirector()->getOpenGLView())条件成立，执行以下的代码：

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CCEGLView *view = CCEGLView::sharedOpenGLView();
view->setFrameSize(w, h);
AppDelegate *pAppDelegate = new AppDelegate();
CCApplication::sharedApplication()->run();

   CCEGLView *view = CCEGLView::sharedOpenGLView();
   view->setFrameSize(w, h);

   AppDelegate *pAppDelegate = new AppDelegate();
   CCApplication::sharedApplication()->run();

同样，我们先获取一个CCEGLView的单例对象，接下来又新建了一个AppDelegate对象，大家可能在工程中找不到AppDelegate类。我们打开工程目录的上一级目录：
我们的Android工程是在proj.android文件夹中，而AppDelegate类就在Classes文件夹中。因为cocos2dx是跨平台的，而AppDelegate在各个平台之间是通用的不需要修改的，所以就放在一个公用的目录下。

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#ifndef _APP_DELEGATE_H_
#define _APP_DELEGATE_H_
#include "cocos2d.h"
/**
@brief The cocos2d Application.
The reason for implement as private inheritance is to hide some interface call by CCDirector.
*/
class AppDelegate : private cocos2d::CCApplication
{
public:
AppDelegate();
virtual ~AppDelegate();
/**
@brief Implement CCDirector and CCScene init code here.
@return true Initialize success, app continue.
@return false Initialize failed, app terminate.
*/
virtual bool applicationDidFinishLaunching();
/**
@brief The function be called when the application enter background
@param the pointer of the application
*/
virtual void applicationDidEnterBackground();
/**
@brief The function be called when the application enter foreground
@param the pointer of the application
*/
virtual void applicationWillEnterForeground();
};
#endif // _APP_DELEGATE_H_

#ifndef  _APP_DELEGATE_H_
#define  _APP_DELEGATE_H_

#include "cocos2d.h"

/**
@brief    The cocos2d Application.

The reason for implement as private inheritance is to hide some interface call by CCDirector.
*/
class  AppDelegate : private cocos2d::CCApplication
{
public:
    AppDelegate();
    virtual ~AppDelegate();

    /**
    @brief    Implement CCDirector and CCScene init code here.
    @return true    Initialize success, app continue.
    @return false   Initialize failed, app terminate.
    */
    virtual bool applicationDidFinishLaunching();

    /**
    @brief  The function be called when the application enter background
    @param  the pointer of the application
    */
    virtual void applicationDidEnterBackground();

    /**
    @brief  The function be called when the application enter foreground
    @param  the pointer of the application
    */
    virtual void applicationWillEnterForeground();
};

#endif // _APP_DELEGATE_H_

AppDelegate是继承CCApplication类的，我们看一下CCApplication的构造方法：

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// sharedApplication pointer
CCApplication * CCApplication::sm_pSharedApplication = 0;
CCApplication::CCApplication()
{
CCAssert(! sm_pSharedApplication, "");
sm_pSharedApplication = this;
}

// sharedApplication pointer
CCApplication * CCApplication::sm_pSharedApplication = 0;

CCApplication::CCApplication()
{
    CCAssert(! sm_pSharedApplication, "");
    sm_pSharedApplication = this;
}

我们看到在新建CCApplication对象时，会把该对象赋给一个全局变量sm_pSharedApplication。所以我们在new AppDelegate()的时候，就把它象赋给全局变量sm_pSharedApplication。我们再看下CCApplication的CCApplication::sharedApplication方法：

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CCApplication* CCApplication::sharedApplication()
{
CCAssert(sm_pSharedApplication, "");
return sm_pSharedApplication;
}

CCApplication* CCApplication::sharedApplication()
{
    CCAssert(sm_pSharedApplication, "");
    return sm_pSharedApplication;
}

此时，sm_pSharedApplication指向的是一个AppDelegate对象。所以我们执行CCApplication::sharedApplication()->run()时其实执行的是AppDelegate对象的run方法。现在我们应该明白这个类为什么叫AppDelegate了，因为CCApplication的工作实际都委托给了AppDelegate类了。看一下AppDelegate的方法：

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int CCApplication::run()
{
// Initialize instance and cocos2d.
if (! applicationDidFinishLaunching())
{
return 0;
}
return -1;
}

int CCApplication::run()
{
    // Initialize instance and cocos2d.
    if (! applicationDidFinishLaunching())
    {
        return 0;
    }
    
    return -1;
}

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bool AppDelegate::applicationDidFinishLaunching() {
// initialize director
CCDirector* pDirector = CCDirector::sharedDirector();
CCEGLView* pEGLView = CCEGLView::sharedOpenGLView();
pDirector->setOpenGLView(pEGLView);
CCSize frameSize = pEGLView->getFrameSize();
// Set the design resolution
#if (CC_TARGET_PLATFORM == CC_PLATFORM_WINRT) || (CC_TARGET_PLATFORM == CC_PLATFORM_WP8)
pEGLView->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, kResolutionShowAll);
#else
pEGLView->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, kResolutionNoBorder);
#endif
vector<string> searchPath;
// In this demo, we select resource according to the frame's height.
// If the resource size is different from design resolution size, you need to set contentScaleFactor.
// We use the ratio of resource's height to the height of design resolution,
// this can make sure that the resource's height could fit for the height of design resolution.
// if the frame's height is larger than the height of medium resource size, select large resource.
if (frameSize.height > mediumResource.size.height)
{
searchPath.push_back(largeResource.directory);
pDirector->setContentScaleFactor(MIN(largeResource.size.height/designResolutionSize.height, largeResource.size.width/designResolutionSize.width));
}
// if the frame's height is larger than the height of small resource size, select medium resource.
else if (frameSize.height > smallResource.size.height)
{
searchPath.push_back(mediumResource.directory);
pDirector->setContentScaleFactor(MIN(mediumResource.size.height/designResolutionSize.height, mediumResource.size.width/designResolutionSize.width));
}
// if the frame's height is smaller than the height of medium resource size, select small resource.
else
{
searchPath.push_back(smallResource.directory);
pDirector->setContentScaleFactor(MIN(smallResource.size.height/designResolutionSize.height, smallResource.size.width/designResolutionSize.width));
}
// set searching path
CCFileUtils::sharedFileUtils()->setSearchPaths(searchPath);
// turn on display FPS
pDirector->setDisplayStats(true);
// set FPS. the default value is 1.0/60 if you don't call this
pDirector->setAnimationInterval(1.0 / 60);
// create a scene. it's an autorelease object
CCScene *pScene = HelloWorld::scene();
// run
pDirector->runWithScene(pScene);
return true;
}

bool AppDelegate::applicationDidFinishLaunching() {
    // initialize director
    CCDirector* pDirector = CCDirector::sharedDirector();
    CCEGLView* pEGLView = CCEGLView::sharedOpenGLView();

    pDirector->setOpenGLView(pEGLView);
	CCSize frameSize = pEGLView->getFrameSize();

    // Set the design resolution
#if (CC_TARGET_PLATFORM == CC_PLATFORM_WINRT) || (CC_TARGET_PLATFORM == CC_PLATFORM_WP8)
    pEGLView->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, kResolutionShowAll);
#else
    pEGLView->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, kResolutionNoBorder);
#endif

    
    vector<string> searchPath;

    // In this demo, we select resource according to the frame's height.
    // If the resource size is different from design resolution size, you need to set contentScaleFactor.
    // We use the ratio of resource's height to the height of design resolution,
    // this can make sure that the resource's height could fit for the height of design resolution.

    // if the frame's height is larger than the height of medium resource size, select large resource.
	if (frameSize.height > mediumResource.size.height)
	{
        searchPath.push_back(largeResource.directory);

        pDirector->setContentScaleFactor(MIN(largeResource.size.height/designResolutionSize.height, largeResource.size.width/designResolutionSize.width));
	}
    // if the frame's height is larger than the height of small resource size, select medium resource.
    else if (frameSize.height > smallResource.size.height)
    {
        searchPath.push_back(mediumResource.directory);
        
        pDirector->setContentScaleFactor(MIN(mediumResource.size.height/designResolutionSize.height, mediumResource.size.width/designResolutionSize.width));
    }
    // if the frame's height is smaller than the height of medium resource size, select small resource.
	else
    {
        searchPath.push_back(smallResource.directory);

        pDirector->setContentScaleFactor(MIN(smallResource.size.height/designResolutionSize.height, smallResource.size.width/designResolutionSize.width));
    }


    // set searching path
    CCFileUtils::sharedFileUtils()->setSearchPaths(searchPath);
	
    // turn on display FPS
    pDirector->setDisplayStats(true);

    // set FPS. the default value is 1.0/60 if you don't call this
    pDirector->setAnimationInterval(1.0 / 60);

    // create a scene. it's an autorelease object
    CCScene *pScene = HelloWorld::scene();

    // run
    pDirector->runWithScene(pScene);

    return true;
}