I've just used cocos2d-x for creating some games. When I read the HelloWorld.cpp, I saw this line
Scene* HelloWorld::createScene()
That's strange for me. How does it work? A method named creatScene that takes no parameters and returns a pointer to a Scene ?
In different libraries, there are different methods to initialize library or some part of that. So, in this case, it maybe create a new context inside library and return it without any argument. It maybe needs no arguments (use defaults) it this step of get them from somewhere else like configuration file. And note that this is convenient to use this type of initializing. Like this:
rc = redis.Redis() #uses default values for server address
It is really an easy question even it cannot be called as question when you check the source code.
In cocos2d-x, CCScene always create this way.
1. create a Layer, which coded by yourself with a lot of other widgets.
2. create a Scene
3. add the layer to the scene
4. return the scene you create.
Related
In my scene I have a vector with multiple custom sprites. When I tap on one of them, I want an action to be fired on another element on the scene, can be another sprite in the vector, or another node. I have been researching the best way to do this, but I'm not quite sure how to implement it. The options are:
Add a touch listener to the scene, and verify if it was tapped inside the bounds of the sprite with rect. containsPoint(point). And after that, I have to get the sprite that was tapped to do the action I want. For me, it doesn't seems very clean to do it this way. And if two sprites are overlaped, I have to verify if the sprite is behind or in the front in order to retrieve the desired sprite. I followed this example: Touch Event example
Add a touch listener in the subclass of the sprite (my custom sprite). And add onTouchBegan and onTouchEnded inside it. But this way, I don't know how to modify an attribute of another sprite, or another element in the scene (Is it possible to use Delegates like Objective-C does?). I followed this example: Subclass Sprite Example
My main problem is that I don't understand very well how to make a node interact with another node in the scene. I have seen a lot of tutorials, but in all of them, when you interact with a node, it only changes its attributes, not other nodes' attributes.
Thanks in advance.
I shall propose "EventCustom" way :)
You can add in your touchBegan / touchEnded methods (wherever you put them... you got the point...) additional code for passing an EventCusto to the _eventDispatcher and get it announced to the world ;)
EventCustom *e = new EventCustom("MyAwesomeEvent");
e->setUserData(ptrMyFantasticData); //This function takes a void pointer. cheers :)
_eventDispatcher->dispatchEvent(e);
You may subclass the EventCustom class but that is hardly necessary. You can always hang an object to it with setUserData().
Now the objects which need to react to the event can listen to it by
_myCustomListener = EventListenerCustom::create(
"MyAwesomeEvent",
CC_CALLBACK_1(
ListeningClass::onMyAwesomeEvent,
this
)
);
_eventDispatcher->addEventListenerWithXXXXXPriority(_myCustomListener, XXX);
//ScreenGraphPriority / FixedPriority depends on situation. Either should work.
It's always a good practice to remove your listeners when you go off, so somewhere, perhaps in onExit(), where you removed touch listeners remove this listener too, as
_eventDispatcher->removeEventListener(_myCustomListener);
Going a bit off the track, a clarification:
CC_CALLBACK_X are a bit tricky names. The X indicates the no. of args the target function will get. Here, event dispatcher will pass 1 arg i.e. ptr to object of EventCustom you handed it, so we use CC_CALLBACK_1. The next arg - here "this" - is the object on which the method will be invoked.
In short, we may say that this callback is going to result into a function call this->onMyAwesomeEvent(e);
For CC_CALLBACK_2 onwards, we can specify additional args, 3rd arg onwards.
Coming back to the issue at hand, ListeningClass::onMyAwesomeEvent will look something like
void ListeningClass::onMyAwesomeEvent(EventCustom *e)
{
MyFantasticData *d = (MyFantasticData *) e->getUserData();
CCLOG("[ListeningClass::onMyAwesomeEvent] %d", d->getMyPreciousInt());
}
Hope it helps :)
Set your elements tags or names with setTag and setName. Then if element x is touched, get them with getChildByTag or getChildByName and do what you need to do.
With the second option you list above.
To make a node interact with another node in the scene you can add touch callback function to your custom sprite object like that:
https://github.com/Longpc/RTS/tree/master/Classes/base/dialogBase
and in main scene you can define function to handle this callback. So you can do every thing to unit in you scene
I'm trying to make a custom sprite, which could receive touch and handle the function as callback.
Okay, first step, receive the touch, easy, we can search it online everywhere.
The one I couldn't do is, I want to make it receive SOMETHING in the class the sprite is created, a function that will be called when the sprite is touched.
I was searching on internet and I think (not really sure) that SEL_Callfunc can do what I want, but I couldn't understand how this one work, so can you guys give me an example please?
For example, my custom class is BSprite, so when I create new object in HelloWorld.cpp, it should be
BSprite* sprite = BSprite::create("HelloWorld.png",HelloWorld::TouchCallback);
Thanks for reading :)
sprite->addTouchEventListener(CC_CALLBACK_0(HelloWorld::onTouchSprite, this));
void HelloWorld::onTouchSprite() {
}
Note: onTouchSprite method should not have any parameters
I would like to change the text of my UIBarButtonItem from another class (objective-C++) that I use in my project.
I have an IBOutlet myButton setup in myViewController and I can successfully do something like:
[ myButton setTitle:#"newTitle" ];
in myViewController.mm
Now I would like to do the same but from myCppClass that I use in my project.
Is there a way for myCppClass to access myViewController's myButton?
Shall I use some type of delegation mechanism?
I am pretty new to Ios and objective-C.
Thanks,
Baba
Create a method within your myViewController class to change the button title, then call that method from myCppClass by following the instructions described in this answer:
How to call method from one class in another (iOS)
https://stackoverflow.com/a/9731162/2274694
The short answer is, don't. You should treat a view controller's views as private. Instead, add a method to your VC like changeButtonTitle. Then call that method from from your other class.
The answers above are correct, but from your comments I suspect you aren't yet happy.
If you are super lazy, and you don't mind the string being the same in all instances of the VC (which in practice is usually the case) you could simply write a getter and setter for the string name as a class variable in the destination class. That way you don't even need access to the actual instance of the class, just its name. Tacky but super easy.
As others have pointed out, don't try and modify the buttons on a different VC directly. Pass a message and have the owning VC do it when it loads.
Well, passing messages forwards (to a new VC) is very easy. At the bottom of every VC class code there is #pragma navigation section commented out which gives you a handle to the destination VC. Cast it to the proper type and you set properties in the destination VC instance. In your case, create a public property NSString which holds the button text in your destination VC, and set it in your navigation section. This could be any class, or even a delegate, but a simple string should work.
Passing messages backwards (to previous VCs) can work the same way but it starts to get messy. You can programatically step back through the stack of VCs to find a particular (instance of) a VC. One of the answers to Get to UIViewController from UIView? gives sample code for stepping back through view controllers.
But if its simply forward communication, passing messages or information through
(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
at the bottom of the VC code and the commented out lines below is very easy and safe.
I reference pullmybeard to work on drag and drop effect.
To do something programmatically, I would use cpp rather than QML itself.
But I face problem in setting property variables. Here is my code segments:
Container *playerContainer = Container::create();
playerContainer->setLayout(new AbsoluteLayout);
playerContainer->setLayoutProperties(AbsoluteLayoutProperties::create().x(posX).y(posY));`
I would set a variables to this playerContainer in order to store positionX and Y. Like pullmybeard, inside ImageView id:beard, it sets property real dy. So, it can be used in onTouch hander.
I think you are looking for a way to pass attributes from your C++ to your QML.
To do that, you can use setContextProperty("propertyName", property)
You can have a look there to see how to implement it : http://developer.blackberry.com/cascades/documentation/dev/integrating_cpp_qml/
I connected C++ and QML via a mediator-class and have everything working in both directions but this one puzzles me.
This is how I connect the mediator-class:
// Initialize Mediator between QML and C++
QmlCppMediator m_qmlCppMediator;
QDeclarativeContext *context = viewer.rootContext();
context->setContextProperty("cppInterface", &m_qmlCppMediator);
How to fire off an ordinary Property-Animation from within C++ ?
Ok I can answer this myself already.
I went for an approach described here http://qt-project.org/doc/qt-4.8/qdeclarativeanimation.html
I bind the “state” of the object which I try to animate to a Q_PROPERTY in the C++ interface.
The different states are linked to transitions (in QML) which do the animate the object.
Rather an easy way would be to define a JavaScript function inside the QML file itself, lie this:
function startAnimation() {
animationID.running = true;
}
Now call this code from C++, simple!