Cocos2dx Box2D-b2body GetUserData始终返回null [英] Cocos2dx Box2D - b2body GetUserData always returns null

问题描述

一辆汽车和一个自行车物件。 Collison检测时。我需要知道哪个（汽车或自行车）与墙壁碰撞。为此使用body-> getuserdata。但它始终返回null。我感到困惑，为什么会为空。我错了吗？

我将其引用为链接，但与我相同。没有用。

汽车代码：-

  sprintf（temp，CAR_BODY_CAR_PLIST） ; 
 m_Texture [2] = new TextureObject（temp，spritesheet1,1，true，kTexture2DPixelFormat_Default，2）; 
 
 //添加购物车// 
 b2BodyDef bodyDef; 
 b2FixtureDef FixtureDef; 
 b2PolygonShape geometricShape; 
 b2CircleShape circleShape; 
 bodyDef.position.Set（startPos.x，startPos.y）; 
 bodyDef.type = b2_dynamicBody; 
 ** bodyDef.userData = m_Texture [2]; ** 
 
购物车= m_world-> CreateBody（& bodyDef）; 
 
夹具DEF。密度= 25.0f; 
 FixtureDef.friction = 0.3f; 
 FixtureDef.restitution = 0.1f; 
 FixtureDef.filter.categoryBits = 0x0008; 
 fixtureDef.filter.maskBits = 0x0003; 
 fixtureDef.density = 0.0f; 
 FixtureDef.isSensor = true; 
 b2Vec2点[6] = 
 {
 
 b2Vec2（0.7f，0.0f），
 b2Vec2（0.7f，3.25f），
 b2Vec2 （-0.7f，3.25f），
 b2Vec2（-0.7f，0.0f），
}； 
多边形Shape.Set（点，4）; 
 m_RiderTest = cart-> CreateFixture（& fixtureDef）; 
（（（GroundTestCallback *）m_GroundRayCastTest）-> addIgnoreFixture（m_RiderTest）; 
 FixtureDef.isSensor = false; 
 FixtureDef.density = 25.0f; 
 
 
 
 FixtureDef.filter.categoryBits = 0x0010; 
 FixtureDef.filter.maskBits = 0x0007; 
多边形Shape.SetAsBox（TEST_SCALE * 0.4f，TEST_SCALE * 0.15f，axel1Pos，axel1Angle）; 
（（（TestCallback *）Test）-> addIgnoreFixture（cart-> CreateFixture（& fixtureDef））; 
 
polygonShape.SetAsBox（0.4f * axel2Length，TEST_SCALE * 0.15f，axel2Pos，axel2Angle）; 
（（（TestCallback *）Test）-> addIgnoreFixture（cart-> CreateFixture（& fixtureDef））; 
  

纹理类别：-

  TextureObject :: TextureObject（char * texturename，CCNode * layer，int zOrder，bool isFrameCache，CCTexture2DPixelFormat pixFormat，int tag）
 {
 CCTexture2D :: setDefaultAlphaPixelFormat（pixFormat）; 
 CCSprite * newSprite = CCSprite :: createWithSpriteFrameName（texturename）; 
 m_Layer =图层； 
 m_Layer-> addChild（newSprite，zOrder）; 
 newSprite-> setTag（tag）; 
 m_Texture = newSprite; 
 CCTexture2D :: setDefaultAlphaPixelFormat（kTexture2DPixelFormat_Default）; 
} 
  

在墙上的课：-（检测Collison检测）

  bool wall :: HandleBeginContact（b2Fixture * fixtureA，b2Fixture * fixtureB）
 {
 b2Fixture * myFixture = m_MainCollision-> GetFixtureList （）; 
 if（myFixture ==夹具A || myFixture ==夹具B）
 {
 b2Body * bodyA = myFixture-> GetBody（）; 
 ** CCSprite * sprite =（CCSprite *）bodyA-> GetUserData（）; ** // spriteA正在获取空值
 CCLog（ spritea =％d，sprite-> getTag（） ）; 
 if（sprite-> getTag（）== 2）
 {
 //骑车离开，它将从起点开始坐姿
} 
} 
返回false； 
} 
  

解决方案

像这样尝试：-

  bool wall :: HandleBeginContact（b2Fixture * fixtureA，b2Fixture * fixtureB）
 {
 b2Body * bodyA = FixtureA-> GetBody（）; 
 b2Body * bodyB =夹具B-> GetBody（）; 
 if（CartBody == bodyA || CartBody == bodyB）
 {
 CCLog（ am正确碰撞）; 
} 
返回false； 
} 
  

am having one car and one bike object. at the time of collison detction. i need to get which(Car or bike) is colliding with wall. for that am using body->getuserdata . but it always returns null. am confuse d that why am getting null. were am wrong?

i refer this link but same as i did. not useful.

Code for car:-

sprintf(temp,CAR_BODY_CAR_PLIST);
m_Texture[2] = new TextureObject(temp,spritesheet1,1,true,kTexture2DPixelFormat_Default,2);  

 // add cart //
        b2BodyDef bodyDef;
        b2FixtureDef fixtureDef;
        b2PolygonShape polygonShape;
        b2CircleShape circleShape;
        bodyDef.position.Set(startPos.x,startPos.y);
        bodyDef.type = b2_dynamicBody;
        **bodyDef.userData = m_Texture[2];**

        cart = m_world->CreateBody(&bodyDef);

        fixtureDef.density = 25.0f;
        fixtureDef.friction = 0.3f;
        fixtureDef.restitution = 0.1f;
        fixtureDef.filter.categoryBits = 0x0008;
        fixtureDef.filter.maskBits = 0x0003;
        fixtureDef.density = 0.0f;
        fixtureDef.isSensor = true;
        b2Vec2 points[6] = 
        {

            b2Vec2(0.7f,0.0f),
            b2Vec2(0.7f,3.25f),
            b2Vec2(-0.7f,3.25f),
            b2Vec2(-0.7f,0.0f),
        };
        polygonShape.Set(points,4);
        m_RiderTest = cart->CreateFixture(&fixtureDef);
        ((GroundTestCallback*)m_GroundRayCastTest)->addIgnoreFixture(m_RiderTest);
        fixtureDef.isSensor = false;
        fixtureDef.density = 25.0f;



        fixtureDef.filter.categoryBits = 0x0010;
        fixtureDef.filter.maskBits = 0x0007;
        polygonShape.SetAsBox(TEST_SCALE*0.4f, TEST_SCALE*0.15f, axel1Pos, axel1Angle);
        ((TestCallback*)Test)->addIgnoreFixture(cart->CreateFixture(&fixtureDef));

        polygonShape.SetAsBox(0.4f*axel2Length, TEST_SCALE*0.15f, axel2Pos, axel2Angle);
        ((TestCallback*)Test)->addIgnoreFixture(cart->CreateFixture(&fixtureDef));

texture class:-

TextureObject::TextureObject(char *texturename,CCNode *layer, int zOrder, bool isFrameCache,CCTexture2DPixelFormat pixFormat, int tag)
{
            CCTexture2D::setDefaultAlphaPixelFormat(pixFormat);
            CCSprite *newSprite = CCSprite::createWithSpriteFrameName(texturename);
            m_Layer = layer;
            m_Layer->addChild(newSprite,zOrder);
            newSprite->setTag(tag);
            m_Texture = newSprite;
            CCTexture2D::setDefaultAlphaPixelFormat(kTexture2DPixelFormat_Default);
}

at wall class:-(Detecting collison detction)

bool wall::HandleBeginContact(b2Fixture *fixtureA,b2Fixture *fixtureB)
{
        b2Fixture *myFixture = m_MainCollision->GetFixtureList();
        if(myFixture == fixtureA || myFixture == fixtureB )
        {
            b2Body *bodyA =  myFixture->GetBody();
            **CCSprite *sprite = (CCSprite *) bodyA->GetUserData();**  // spriteA am getting null
            CCLog("spritea = %d",sprite->getTag());
            if (sprite->getTag() == 2)
            {
                // rider out and it will satrt from start point
            }
        }
    return false;
}

解决方案

Try Like this:-

   bool wall::HandleBeginContact(b2Fixture *fixtureA,b2Fixture *fixtureB)
    {
        b2Body *bodyA =  fixtureA->GetBody();
        b2Body *bodyB =  fixtureB->GetBody();
        if(CartBody == bodyA || CartBody == bodyB )
        {
            CCLog("am collided correctly");
        }
        return false;
    }

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