在Cocos2d-x3.0里面如何使用物理引擎：弹球

HelloWorldScene.h

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include "cocos2d.h"

USING_NS_CC;

class HelloWorld : public cocos2d::Layer
{
public:
	// there's no 'id' in cpp, so we recommend returning the class instance pointer
	static cocos2d::Scene* createScene();

	// Here's a difference. Method 'init' in cocos2d-x returns bool, instead of returning 'id' in cocos2d-iphone
	virtual bool init();  

	// a selector callback
	void menuCloseCallback(Object* pSender);

	// implement the "static create()" method manually
	CREATE_FUNC(HelloWorld);

	void setPhyWorld(PhysicsWorld* world){m_world = world;}

	virtual bool onTouchBegan(Touch *touch, Event *unused_event);
	virtual void onTouchEnded(Touch *touch, Event *unused_event);

	void addNewSpriteAtPosition(Point p);

private:
	PhysicsWorld* m_world;

	//bool onContactBegin(EventCustom* event, const PhysicsContact& contact);

	bool onContactBegin(PhysicsContact& contact);
};

#endif // __HELLOWORLD_SCENE_H__

HelloWorldScene.cpp

#include "HelloWorldScene.h"

USING_NS_CC;

Scene* HelloWorld::createScene()
{
	// 'scene' is an autorelease object
	//add physicals
	auto scene = Scene::createWithPhysics();
	//DrawMask参数可以选择打开绘制哪些部分比如，Joint、Shape、Contact等等
	scene->getPhysicsWorld()->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_ALL);

	//创建一个边界
	Size visibleSize = Director::getInstance()->getVisibleSize();
	//使用PhysicalsBody的create方法创建自己想要的物体。
	//PHYSICSBODY_MATERIAL_DEFAULT宏表示的是创建的Body的默认材质，3是边线宽度。编译运行我们会看到场景边上有红色的边界。
	auto body = PhysicsBody::createEdgeBox(visibleSize, PHYSICSBODY_MATERIAL_DEFAULT, 3);
	auto edgeNode = Node::create();
	edgeNode->setPosition(Point(visibleSize.width/2,visibleSize.height/2));
	edgeNode->setPhysicsBody(body);
	scene->addChild(edgeNode);

	// 'layer' is an autorelease object
	auto layer = HelloWorld::create();
	//将这个World传到Layer中。所以我们在HelloWorld类中加入一个函数。将这个world存起来。
	layer->setPhyWorld(scene->getPhysicsWorld());

	// add layer as a child to scene
	scene->addChild(layer);

	// return the scene
	return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
	//////////////////////////////
	// 1. super init first
	if ( !Layer::init() )
	{
		return false;
	}

	Size visibleSize = Director::getInstance()->getVisibleSize();
	Point origin = Director::getInstance()->getVisibleOrigin();

	/////////////////////////////
	// 2. add a menu item with "X" image, which is clicked to quit the program
	//    you may modify it.

	// add a "close" icon to exit the progress. it's an autorelease object
	auto closeItem = MenuItemImage::create(
		"CloseNormal.png",
		"CloseSelected.png",
		CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));

	closeItem->setPosition(Point(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
		origin.y + closeItem->getContentSize().height/2));

	// create menu, it's an autorelease object
	auto menu = Menu::create(closeItem, NULL);
	menu->setPosition(Point::ZERO);
	this->addChild(menu, 1);

	/////////////////////////////
	// 3. add your codes below...

	// add a label shows "Hello World"
	// create and initialize a label

	auto label = LabelTTF::create("Hello World", "Arial", 24);

	// position the label on the center of the screen
	label->setPosition(Point(origin.x + visibleSize.width/2,
		origin.y + visibleSize.height - label->getContentSize().height));

	// add the label as a child to this layer
	this->addChild(label, 1);

	// new way to enable touch
	auto touchListener = EventListenerTouchOneByOne::create();
	touchListener->onTouchBegan = CC_CALLBACK_2(HelloWorld::onTouchBegan, this);
	touchListener->onTouchEnded = CC_CALLBACK_2(HelloWorld::onTouchEnded, this);
	_eventDispatcher->addEventListenerWithSceneGraphPriority(touchListener, this);

	// 碰撞检测回调
	auto contactListener = EventListenerPhysicsContact::create();
	contactListener->onContactBegin = CC_CALLBACK_1(HelloWorld::onContactBegin, this);
	_eventDispatcher->addEventListenerWithSceneGraphPriority(contactListener, this);
	return true;
}

bool HelloWorld::onContactBegin(PhysicsContact& contact)
{
	auto sp = (Sprite*)contact.getShapeA()->getBody()->getNode();
	int tag = sp->getTag();
	CCLOG("onContactBegin: %d", tag);
	return true;
}

bool HelloWorld::onTouchBegan(Touch *touch, Event *unused_event)
{
	return true;
}

void HelloWorld::onTouchEnded(Touch *touch, Event *unused_event)
{
	auto location = touch->getLocation();
	addNewSpriteAtPosition(location);
}

//然后我们来实现addNewSpriteAtPosition函数。
//关联body与sprite从未如此简单，我们只需创建一个body，创建一个sprite然后将body设置为sprite的body即可。
void HelloWorld::addNewSpriteAtPosition(Point p)
{
	auto sprite = Sprite::create("ball.png");
	sprite->setTag(1);
	auto body = PhysicsBody::createCircle(sprite->getContentSize().width / 2);
	sprite->setPhysicsBody(body);
	sprite->setPosition(p);
	this->addChild(sprite);
}

void HelloWorld::menuCloseCallback(Object* pSender)
{
	//控制PhysicsWorld debugDraw的绘制
	if(m_world->getDebugDrawMask() != PhysicsWorld::DEBUGDRAW_NONE) {
		m_world->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_NONE);
	} else {
		m_world->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_ALL);
	}
}

AppDelegate.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 Director.
*/
class  AppDelegate : private cocos2d::Application
{
public:
    AppDelegate();
    virtual ~AppDelegate();

    /**
    @brief    Implement Director and Scene 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.cpp

#include "AppDelegate.h"
#include "HelloWorldScene.h"

USING_NS_CC;

AppDelegate::AppDelegate() {

}

AppDelegate::~AppDelegate() 
{
}

bool AppDelegate::applicationDidFinishLaunching() {
    // initialize director
	// initialize director
	auto director = Director::getInstance();
	auto glview = director->getOpenGLView();
	if(!glview) {
		glview = GLViewImpl::create("My Game");
		director->setOpenGLView(glview);
	}
	
    // turn on display FPS
    director->setDisplayStats(true);

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

	glview->setDesignResolutionSize(800, 600, ResolutionPolicy::EXACT_FIT);

    // create a scene. it's an autorelease object
    auto scene = HelloWorld::createScene();

    // run
    director->runWithScene(scene);

    return true;
}

// This function will be called when the app is inactive. When comes a phone call,it's be invoked too
void AppDelegate::applicationDidEnterBackground() {
    Director::getInstance()->stopAnimation();

    // if you use SimpleAudioEngine, it must be pause
    // SimpleAudioEngine::sharedEngine()->pauseBackgroundMusic();
}

// this function will be called when the app is active again
void AppDelegate::applicationWillEnterForeground() {
    Director::getInstance()->startAnimation();

    // if you use SimpleAudioEngine, it must resume here
    // SimpleAudioEngine::sharedEngine()->resumeBackgroundMusic();
}

用到的图片