sprite未更新到正確的位置

Question

我已經編寫了一個代碼來顯示使用CCLog時精靈的位置，當一個鼠標聯合移動它被釋放時。下面是Sprite.mm類和ccTouchesEnded方法（它在HelloWorldLayer.mm類中）。精靈位置不更新，輸出始終爲x：0.00和y：0.00。

Sprite.mm：

-(id)addSprite:(CCLayer *)parentLayer 
       inWorld:(b2World *)world 
{ 
PhysicsSprite *aSprite = [PhysicsSprite spriteWithFile:@"spriteIm.png"]; 

aSprite.tag = 1; 
[parentLayer addChild:aSprite]; 

b2BodyDef spriteBodyDef; 
spriteBodyDef.userData = aSprite; 
spriteBodyDef.type = b2_dynamicBody; 
CGSize s = [CCDirector sharedDirector].winSize; 
spriteBodyDef.position = [Convert toMeters:ccp(s.width * 0.25,s.height-400)]; 
b2FixtureDef fixtureDef; 
fixtureDef.density = 0.01; 
b2CircleShape circleShape; 
circleShape.m_radius = aSprite.contentSize.width/2/PTM_RATIO; 
fixtureDef.shape = &circleShape; 

spriteBody = world->CreateBody(&spriteBodyDef); 
spriteFixture = spriteBody->CreateFixture(&fixtureDef); 

[aSprite setPhysicsBody:spriteBody]; 

return aSprite; 
} 

ccTouchesEnded：

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 

if (mouseJoint) 
{ 
    for(b2Body *b = world->GetBodyList(); b; b=b->GetNext()) { 
    if (b->GetUserData() != NULL) { 
     CCSprite *mySprite = (CCSprite *)b->GetUserData(); 
     if (mySprite.tag == 1) { 
      CGPoint spritePosition = mySprite.position; 
      CCLOG(@"the sprite position is x:%0.2f, y:%0.2f", spritePosition.x, spritePosition.y); 
     } 
    } 
}   

world->DestroyJoint(mouseJoint); 
mouseJoint = NULL; 
} 
} 

請幫助。我已經呆了幾天了。

Answer 1

我終於設法讓它工作。我猜測x：0.00和y：0.00是因爲我採取了精靈的位置而不是身體。精靈是身體的父親，所以它將它的位置放在父母的內部，這是0,0。這是我的理解。以下是我對ccTouchesEnded代碼所做的更改。

ccTouchesEnded：

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 

if (mouseJoint) 
{ 
    for(b2Body *b = mouseJoint->GetBodyB(); b; b=b->GetNext()) { 
     if (b->GetUserData() != NULL) 
     { 
      CCSprite *mySprite = (CCSprite*)b->GetUserData(); 

      if (mySprite.tag == 1) { 
       mySprite.position = CGPointMake(b->GetPosition().x * PTM_RATIO, b->GetPosition().y * PTM_RATIO); 
       CCLOG(@"the sprite postion is x:%0.2f , y:%0.2f", mySprite.position.x, mySprite.position.y); 

      } 
     } 
    } 

    world->DestroyJoint(mouseJoint); 
    mouseJoint = NULL; 
} 
}