How to get position of CCSprite added to CCParallaxNode?

Question

I have a CCparallaxNodeExtras that scrolls infinite (following the space game tutorial). I added as a child a CCSprite made of other CCSprite, like this:

_backgroundNode = CCParallaxNodeExtras::node();
this->addChild(_backgroundNode,-2);

    float acum = 0.0;
    back1 = CCSprite::create();
    for(int i = 0; i < num_repeats; ++i) {
        CCSprite *back = CCSprite::createWithSpriteFrameName("rock.png");
        back->setPosition(ccp(acum, 0));
        back1->addChild(back);
        acum+= back->getContentSize().width+150.0;
    }

    _backgroundNode->addChild(back1,  1 , ccp(0.1,0.1), ccp(0, winSize.height * 0.64));

now in my update I have this:

CCPoint backgroundScrollVert = ccp(-1024, 0);
_backgroundNode->setPosition(ccpAdd(_backgroundNode->getPosition(), ccpMult(backgroundScrollVert, dt)));

perfect, the background moves and disappears (that is what I want for now) but I need to get the collision between the sprites on that background and a fixed sprite as a child of the main node.

The problem is that whenever I try to get the collision by the simple way (intersecting the bounding boxes) it doesn't work, so I tried to just get the position of the sprites and all I get is the position fixed in the CCSprite (back1) composed by the sprites (back).

Now, is there a possible way to get the position of any individual sprite located in that parallax node? If i try something like:

CCSprite *tempsprite = (CCSprite*)_backgroundNode->getChildren()->objectAtIndex(0);
printf("%f\n", tempsprite->getChildren()->objectAtIndex(0)->getPositionX());

it prints always the same value, it is like the position is not being affected by the transformation of the parent in the background node... so, how do I get it correctly? how do I get the position relative to screen and not to the parent?

Answer 1

The position of the child is the relative position of the child plus the position of the parent.

So the x position of the child would be something like:

tempsprite->getChildren()->objectAtIndex(0)->getPositionX() + tempsprite->getPositionX();