Question

I have written a code to display using CCLog the exact position of a sprite when a mousejoint moving it is released. Below is the Sprite.mm class and the ccTouchesEnded method (which is in the HelloWorldLayer.mm class). The sprite position is not updating, the output is constantly x: 0.00 and 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;
}
}

Please help. I’ve been at it for a few days.

Answer 1

I finally managed to get it working. I guess the x:0.00 and y:0.00 were because I was taking the position of the sprite not the body. The sprite is parented to the body so it was giving its position inside it’s parent, which is 0,0. This is how I understand it. Here are the changes I made to the ccTouchesEnded code.

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;
}
}