cocos2d-x 之 CCPhysicsSprite 基于物理引擎的Sprite

叁歲伎倆 2022-05-13 03:10 173阅读 0赞

### 勤奋努力，持之以恒！ ###

box2d简单介绍可参阅：[http://blog.csdn.net/song\_hui\_xiang/article/details/34116399][http_blog.csdn.net_song_hui_xiang_article_details_34116399]

写这篇文章主要是说明：对一个刚体施加一个力，用 GetWorldVector() 与不用的区别。刚开始学习box2d，因为这个问题被虐了好几天，贴出来一是分享，二是备忘。下面直接上代码：

//
    //  Game.h
    //  HeroJump
    //
    //  Created by XiangZi on 14-6-27.
    //
    //
    
    #ifndef __HeroJump__Game__
    #define __HeroJump__Game__
    
    #include "cocos2d.h"
    #include "Box2D.h"
    #include "cocos-ext.h"//用CCPhysicsSprite类需要导入此头文件
    using namespace std;
    USING_NS_CC_EXT;
    USING_NS_CC;
    
    enum GameTag{
        kTag,
    };
    enum MenuTag{
        
    };
    enum GamezOrder{
        zOrder,
    };
    
    class Game : public CCLayer {
    public:
        ~Game();
        Game();
        static CCScene* scene();
        void initPhysics();
        virtual void draw();
        void update(float dt);
        CCPhysicsSprite* createNewPhysicsSprite(const char *imageName);
        
        virtual void onEnter();
        virtual void onExit();
        virtual bool ccTouchBegan(CCTouch *pTouch, CCEvent *pEvent);
        virtual void ccTouchMoved(CCTouch *pTouch, CCEvent *pEvent);
        virtual void ccTouchEnded(CCTouch *pTouch, CCEvent *pEvent);
    private:
        b2World* world;
        CCSize size;
    };
    
    #endif /* defined(__HeroJump__Game__) */

.cpp

//
    //  Game.cpp
    //  HeroJump
    //
    //  Created by XiangZi on 14-6-27.
    //
    //
    
    #include "Game.h"
    
    #define PTM_RATIO 32
    
    Game::Game()
    {
        setAccelerometerEnabled( true );
        size = CCDirector::sharedDirector()->getWinSize();
        //创建物理世界
        b2Vec2 gravity;
        gravity.Set(0.0f, -10.0f);
        world = new b2World(gravity);
        world->SetAllowSleeping(true);
        world->SetContinuousPhysics(true);
        
        b2BodyDef groundBodyDef;
        groundBodyDef.position.Set(0, 0);
        b2Body* groundBody = world->CreateBody(&groundBodyDef);
        b2EdgeShape groundBox;
        // bottom
        groundBox.Set(b2Vec2(0,0), b2Vec2(size.width/PTM_RATIO,0));
        groundBody->CreateFixture(&groundBox,0);
        // top
        groundBox.Set(b2Vec2(0,size.height/PTM_RATIO), b2Vec2(size.width/PTM_RATIO,size.height/PTM_RATIO));
        groundBody->CreateFixture(&groundBox,0);
        // left
        groundBox.Set(b2Vec2(0,size.height/PTM_RATIO), b2Vec2(0,0));
        groundBody->CreateFixture(&groundBox,0);
        // right
        groundBox.Set(b2Vec2(size.width/PTM_RATIO,size.height/PTM_RATIO), b2Vec2(size.width/PTM_RATIO,0));
        groundBody->CreateFixture(&groundBox,0);
        
        this->initPhysics();
        scheduleUpdate();
    }
    Game::~Game()
    {
        delete world;
        world = NULL;
    }
    
    void Game::initPhysics()
    {
        CCPhysicsSprite* sprite = createNewPhysicsSprite("Icon.png");
        sprite->setPosition(ccp(size.width/2, size.height/2));
        this->addChild(sprite,1,1234);
    }
    
    //封装此方法用于创建一物理精灵
    CCPhysicsSprite* Game::createNewPhysicsSprite(const char *imageName)
    {
        CCPhysicsSprite* physicsSprite = CCPhysicsSprite::create(imageName);
        
        b2BodyDef bodyDef;
        bodyDef.type = b2_dynamicBody;
        
        b2Body* body = world->CreateBody(&bodyDef);
        
        b2PolygonShape polygonShape;
        polygonShape.SetAsBox(physicsSprite->getContentSize().width/PTM_RATIO/2, physicsSprite->getContentSize().height/PTM_RATIO/2);
        
        b2FixtureDef fixtureDef;
        fixtureDef.shape = &polygonShape;
        fixtureDef.density = 5.5f;
        fixtureDef.friction = 0.3f;
        fixtureDef.restitution = 0.1f;
        body->CreateFixture(&fixtureDef);
        
        physicsSprite->setPTMRatio(PTM_RATIO);
        physicsSprite->setB2Body(body);
        
        return physicsSprite;
    }
    
    
    bool Game::ccTouchBegan(CCTouch *pTouch, CCEvent *pEvent)
    {
        CCPoint point = pTouch->getLocation();
        CCPhysicsSprite* sprite = (CCPhysicsSprite*)this->getChildByTag(1234);
        b2Body* body = sprite->getB2Body();
        
        float gravityX = 5.0f;
        float gravityY = 10.0f;
        
        //给body施加一个力。 GetWorldCenter()方法用来获取刚体的重心。
        //b2Vec2 force = body->GetWorldVector(b2Vec2(-gravityX,gravityY));  以此body的坐标系计算向量，body有转动向量方向也会随之转动。
        b2Vec2 force = b2Vec2(-gravityX,gravityY); //以整个wrold世界的坐标系计算向量，不随单个body装动而转动。
        
        if (point.x < size.width/2) {//点击屏幕左半边给予一个左上的速度
            force.x = -gravityX;
        }else{//点击屏幕右半边给予一个右上的速度
            force.x = gravityX;
        }
        //直接影响刚体的速度。setLinearVelocity添加的速度会覆盖刚体原有的速度。
        body->SetLinearVelocity(b2Vec2_zero);
        body->SetAngularVelocity(0);
        body->SetAwake(true);
        body->SetLinearVelocity(force);
        
        return true;
    }
    void Game::ccTouchMoved(CCTouch *pTouch, CCEvent *pEvent){}
    void Game::ccTouchEnded(CCTouch *pTouch, CCEvent *pEvent){}
    
    void Game::onEnter()
    {
        CCDirector::sharedDirector()->getTouchDispatcher()->addTargetedDelegate(this, 0, false);
        CCLayer::onEnter();
    }
    void Game::onExit()
    {
        CCDirector::sharedDirector()->getTouchDispatcher()->removeDelegate(this);
        CCLayer::onExit();
    }
    void Game::update(float dt)
    {
        int velocityIterations = 8;
        int positionIterations = 1;
        world->Step(1.0f/60.0f, velocityIterations, positionIterations);
    }
    void Game::draw()
    {
        CCLayer::draw();
        ccGLEnableVertexAttribs( kCCVertexAttribFlag_Position );
        kmGLPushMatrix();
        world->DrawDebugData();
        kmGLPopMatrix();
    }
    CCScene* Game::scene()
    {
        CCScene *scene = CCScene::create();
        CCLayer* layer = new Game();
        scene->addChild(layer);
        layer->release();
        return scene;
    }

[http_blog.csdn.net_song_hui_xiang_article_details_34116399]: http://blog.csdn.net/song_hui_xiang/article/details/34116399