【麦可网】Cocos2d-X跨平台游戏开发学习笔记---第二十五课：Cocos2D-X物理引擎之Box2D8-10

本文链接：https://blog.youkuaiyun.com/QIULANZHU/article/details/46765669

【麦可网】Cocos2d-X跨平台游戏开发---学习笔记

第二十五课：Cocos2D-X物理引擎之Box2D8-10

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课程目标：

- 学习Box2D

课程重点：

- BOX2D概念

- BOX2D常用操作

- 使用物理编辑器

考核目标：

- 能够使用Box2D常用操作

- 使用物理编辑器完成物理对象编辑

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一、物理编辑器

1.vertexHelper（mac）

2.PhysicsEditor

二、使用PhysicsEditor的实例

HelloPhysicEditor.h
-------------------------------------
#pragma once

#include "cocos2d.h"
#include "Box2D/Box2D.h"
USING_NS_CC;

class HelloPhysicEditor : public cocos2d::CCLayer
{
private:
	CCTexture2D* m_pSpriteTexture;
	b2World* world;

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

	// there's no 'id' in cpp, so we recommend returning the class instance pointer
	static cocos2d::CCScene* scene();

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

	// implement the "static node()" method manually
	CREATE_FUNC(HelloPhysicEditor);

	virtual void ccTouchesEnded(CCSet *pTouches, CCEvent *pEvent);
	void initPhysics();
	void addNewSpriteAtPosition(CCPoint p);
	void updata(float dt);
};

HelloPhysicEditor.cpp
-------------------------------------
#include "HelloPhysicEditor.h"
#include "cocos-ext.h"
#include "GB2ShapeCache-x.h"
using namespace cocos2d::extension;
USING_NS_CC;

enum{
	kTagParentNode = 1,
};
#define PTM_RATIO 32.0f

string names[] = {
	"hotdog",
	"drink",
	"icecream",
	"icecream2",
	"icecream3",
	"hamburger",
	"orange"
};

CCScene* HelloPhysicEditor::scene()
{
	// 'scene' is an autorelease object
	CCScene *scene = CCScene::create();

	// 'layer' is an autorelease object
	HelloPhysicEditor *layer = HelloPhysicEditor::create();

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

	// return the scene
	return scene;
}

HelloPhysicEditor::HelloPhysicEditor():
m_pSpriteTexture(NULL),
world(NULL)
{
//加载physicsEditor生成的文件
	GB2ShapeCache::sharedGB2ShapeCache()->addShapesWithFile("physic_all.plist");
}
HelloPhysicEditor::~HelloPhysicEditor()
{
	CC_SAFE_DELETE(world);
}

// on "init" you need to initialize your instance
bool HelloPhysicEditor::init()
{
	//
	// 1. super init first
	if ( !CCLayer::init() )
	{
		return false;
	}
	setTouchEnabled(true);
	setAccelerometerEnabled(true);

	this->initPhysics();

	CCSpriteBatchNode* blocks = CCSpriteBatchNode::create("blocks.png",100);
	m_pSpriteTexture = blocks->getTexture();
	addChild(blocks, 0, kTagParentNode);

	//scheduleUpdate();
	this->schedule(schedule_selector(HelloPhysicEditor::updata));

	return true;
}


void HelloPhysicEditor::menuCloseCallback(CCObject* pSender)
{

}

void HelloPhysicEditor::ccTouchesEnded(CCSet *pTouches, CCEvent *pEvent)
{
	CCSetIterator it;
	CCTouch* touch;

	for (it=pTouches->begin(); it!=pTouches->end();it++)
	{
		touch = (CCTouch*)(*it);
		if (!touch) break;

		CCPoint location = touch->getLocation();

		addNewSpriteAtPosition( location );
	}

}

void HelloPhysicEditor::initPhysics()
{
	b2Vec2 gravity; 
	gravity.Set(0.0f,-10.0f);
	world = new b2World(gravity);

	world->SetAllowSleeping(true);
	world->SetContinuousPhysics(true);

	//创建物理空间的范围
	b2BodyDef groundBodyDef;
	groundBodyDef.position.Set(0, 0);
	//创建刚体
	b2Body* groundBody = world->CreateBody(&groundBodyDef);

	//创建形状
	b2EdgeShape groundBox;

	//创建夹具
	//将形状绑定到刚体上
	//button
	groundBox.Set(b2Vec2(0,0), b2Vec2(480/PTM_RATIO, 0));
	groundBody->CreateFixture(&groundBox, 0);

	//top
	groundBox.Set(b2Vec2(0,320/PTM_RATIO), b2Vec2(480/PTM_RATIO, 320/PTM_RATIO));
	groundBody->CreateFixture(&groundBox, 0);

	//left
	groundBox.Set(b2Vec2(0,320/PTM_RATIO), b2Vec2(0, 0));
	groundBody->CreateFixture(&groundBox, 0);


	//right
	groundBox.Set(b2Vec2(480/PTM_RATIO,320/PTM_RATIO), b2Vec2(480/PTM_RATIO, 0));
	groundBody->CreateFixture(&groundBox, 0);
}

void HelloPhysicEditor::addNewSpriteAtPosition(CCPoint p)
{
	string name = names[rand()%7];

	//定义刚体
	b2BodyDef bodyDef;
	bodyDef.type = b2_dynamicBody;

	bodyDef.position.Set(p.x/PTM_RATIO, p.y/PTM_RATIO);
	b2Body *body = world->CreateBody(&bodyDef);

	//定义多边形
// 	b2PolygonShape dynamicBox;
// 	dynamicBox.SetAsBox(.5f, .5f);
	GB2ShapeCache* sc = GB2ShapeCache::sharedGB2ShapeCache();
	sc->addFixturesToBody(body, name.c_str());

	//定义夹具
// 	b2FixtureDef fixtureDef;
// 	fixtureDef.shape = &dynamicBox;		//形状
// 	fixtureDef.density = 1.0f;			//密度
// 	fixtureDef.friction = 0.3f;			//摩擦系数
// 	body->CreateFixture(&fixtureDef);
// 
// 	CCNode* parent = this->getChildByTag(kTagParentNode);
// 
// 	int idx = (CCRANDOM_0_1() < 0.5 ? 0 : 1);
// 	int idy = (CCRANDOM_0_1() < 0.5 ? 0 : 1);
// 	if (idx==0 && idy==0)
// 	{
// 		int a =100;
// 		body->SetUserData(&a);
// 	}

// 	CCPhysicsSprite* sprite = CCPhysicsSprite::createWithTexture(m_pSpriteTexture, CCRectMake(32*idx, 32*idy, 32, 32));
// 	parent->addChild(sprite);
// 	sprite->setB2Body(body);
// 	sprite->setPTMRatio(PTM_RATIO);
	//sprite->setPosition( ccp( p.x, p.y) );//添加上这句在快速创建物理精灵时会出错

	CCPhysicsSprite* sprite = CCPhysicsSprite::create( (name+".png").c_str());
	this->addChild(sprite);
	sprite->setB2Body(body);
	sprite->setPTMRatio(PTM_RATIO);
	//sprite->setPosition( ccp(p.x	, p.y) );

	sprite->setAnchorPoint(sc->anchorPointForShape(name.c_str()));
}

void HelloPhysicEditor::updata(float dt)
{
	int velocityIterations = 8;
	int positionIterations = 1;

	world->Step(dt, velocityIterations, positionIterations);

#if 0
	//遍历刚体
	for (b2Body* b=world->GetBodyList(); b; b=b->GetNext())
	{
		int* tmp = (int*)b->GetUserData();
		if (*tmp == 100)
		{
			//千万不要在这里直接删除b指向的body对象，缓存后在后面删除
			CCLOG("body is a");
		}

	}

	//遍历碰撞点
	for ( b2Contact* c=world->GetContactList(); c; c=c->GetNext() )
	{
		千万不要在这里直接删除c指向的碰撞点对象，缓存后在后面删除
	}

#endif	
}

视频中GB2ShapeCache-x.cpp的下载地址：
http://download.youkuaiyun.com/download/yclmy/8408533

===================================================================

总结：

物理编辑器真的太方便啦！

开心一刻：

蝙蝠深爱麻雀，却被拒绝，

蝙蝠：“为什么，这一切都是为什么？”

麻雀：“俺妈说了，长得黑也就算了，总爱晚上出去的男人都不是好鸟！”

【麦可网】Cocos2d-X跨平台游戏开发---教程下载:http://pan.baidu.com/s/1kTio1Av

【麦可网】Cocos2d-X跨平台游戏开发---笔记系列:http://blog.youkuaiyun.com/qiulanzhu