Hi,

I'm getting my hands a bit deeper into AS and I've ran into some stuff that I can't find documentation for. First, I'll describe our engine a bit so hopefully you get a better idea of what I'm trying to achieve.

The game engine in which I'm trying to integrate AngelScript is heavily based on a component design. Everything in the engine is a component, and the entity concept does not exist. Even the content of the main loop is a special type of component.

In our engine, a component can declare dependencies that must be bound within our Editors. For example, let's say I implement a wandering cat's behavior. I'll need a dependency on it's animation system and it's rigid body. All of this is done through the framework and does not need lot's of typing by the end-user. Using a strong framework, it's easy for us, developpers of the said framework, to enforce and automate some normally cumbersome & error-prone functionalities, such as memory management, serialization, updates, etc... Add a complete tool set of this and code reflexion and you get a pretty flexible and adaptable game engine.

So, up to now, we would code our game code in C++ directly within a Game project built on top of the framework. However, as project grow bigger, it is becoming longer and longer to compile and a development iteration is getting a bit longer. There came in the need for scripts.

Now, as everything is a component, and we don't want to change the workflow's philosophy that much for our game programmers, we would really like to implement a component directly within scripts.

Basically, a component is 4 default function of initialization and de-initialization and a custom, per-module define, update function if any. For example, an AI component has an Update() function. An animation system component has an Animate(const f32 deltaTime) function.

Now, let's say I wish to define two components using script, and I want both to communicate with each other, but each one has it's own lifetime and scope ( we're heavily based on dynamic loading ... )

So I have defined a ScriptedAIInstance which holds a asIScriptObject* and a context. When it's function Update is called, it calls the Update function defined within the script. So far so good, this work perfectly and without any trouble.

Now, I would like one instance's Update to do something like that :

In AngelScript :

class A
{

void DoSomething()
{
//...
}

};

class B
{

void Update()
{
A@ a = GetComponent("A", 0);

a.DoSomething();
}

};

I've tried exposing a GetComponent() function and using the asGetActiveContext method. The trouble is, I don't know what kind of objects I need to pass. Is there a base object that I can use for that ? Or something such as a void* that I can cast from the script side ?

void* GetComponent(const String& name)
{
AIScriptInstance* instance = static_cast<AIScriptInstance*>(asGetActiveContext());
return instance->GetLinkedInstance().GetAsIScriptObject();
}

Thanks for any help that you may give me. I'm really new to AS and I really want it to work within our engine given all the cool feature it supports.

After much trial and error I finally got to succeed doing what I wanted. However, since I'm no AngelScript Guru, I'd like some advice as to whether I'm doing something horribly wrong or if it's fine.

Here my test script :

class A
{
u32 m_value;

void Init()
{
m_value = 0;
}

void Update()
{
Print("\n Value from A : ");
Print(m_value);

m_value++;
}

u32 GetValue()
{
return m_value;
}
};

class B
{
void Update()
{
A@ a;
GetComponent(@a);

Print("\n Value from B :");
Print(a.GetValue());
}
};

I have registered my GetComponent() function as below, really simple/prototype stuff for now as I'm still making learning tests :

ANGELSCRIPT_CHECKED_CALL(m_engine->RegisterGlobalFunction("void GetComponent(?& out)", asFUNCTION(Wrappers::GetComponent), asCALL_CDECL));

Finally, the GetComponent function is implemented as below :

//------------------------------------------------------------------------
static void GetComponent(void* component, int)
{
AIScriptInstance* instanceOwner = static_cast<AIScriptInstance*>(asGetActiveContext()->GetUserData());

instanceOwner->GetComponent()->GetAsIScriptObject()->AddRef();
*static_cast<void**>(component) = instanceOwner->GetComponent()->GetAsIScriptObject();
}

I had a problem because I didn't add the AddRef call on the returned object. My question is :

Do I need to release this reference at some point ? Am I increasing infenitely the ref count of my object ? My AIScriptInstance holds an instance of the asIScriptObject and it's also releasing it once he's destroyed.

Thanks a lot,

Pierre

Thanks once again, that clarified things.

On a side note, thanks for the input on interfaces. I really want to limit the coupling of data types to avoid having the universe to build upon a live modification of the code. My design, both in the GUI ( because I'm building a GUI for edition and remote debugging on consoles ) is to actually display modules such as it is done within Visual Studio. ( Each module being the equivalent of an assembly )

My main problem with interfaces, however, is that they must be registered in C++ code through the asIScriptEngine class right ? I was actually wondering if it was possible to register an interface through script. I highly doubt that I can register an interface from the script, even if I wrapped the RegisterInterface/RegisterInterfaceMethod in C++ code since a script relying on that interface being registered may be loaded prior to the script register interface being executed. Is that right ?

Finally, since I have base instance component with a dependency on a script component ( the script text itself ) in my code who's responsibility is to manage the asIScriptObject, deferring calls to it, managing the access to externally held script & engine objects, I was thinking of raising a signal, caught by all instances, through the script component should it be reloaded ( through our live edition network bridge ) to actually trigger a rebuild of the asIScriptModule. I haven't actually tried yet, but judging from previous posts, I think it's a reasonable idea.

The only areas which I see as being problematic are what to do with the asIScriptObject that I already have and how to handle properties which have been added/removed/modified without modifying the other values. I guess I'll find out tomorrow :)

Anyway, the more I play with AS, the more I like it.

Keep up the good work,

Pierre

Wonderful ! That's even better than I had hoped.