for a personal project I am creating a series of components for C++ Builder which manipulate D3D8. Now then..... Is this generally seen as acceptable? class D3D { private: LPDIRECT3DDEVICE device; : : public: LPDIRECT3DDEVICE GetDevice(); : : }; and then passing that Device to a model class to render I am a bit worried about the GetDevice() because a: it exposes the main part of the class to the open world. b: means having many copies of the Device object in the models (could be static I know but thats for later) c: makes code unreadable i.e. Model->initialize(Scene->GetDevice()); - we shouldn''t put the programmer through this should we? Ideas and notes would be welcomed Neil

BUT....
What if someone says
LPDIRECT3DDEVICE dev=Scene->GetDevice();

Firstly I dont want the component user to have access to change environment settings - this could mess things up in the app if the setting isn''t supported (basic example - if texturing is set to multitexture on a card with only one texture unit (OK it''s a bad example as most cards do have support for multitexture)).

Also i see it as bad practice to HAVE to call a method like this
Model->Init(Scene->GetDevice());

The idea is that the user shouldn''t know/care what is doing the drawing (therefore we cannot assume familiarity with D3D) and the components must be easy to use (if only for my own sake).

Would ''friend''s work? I''ve read about them but the syntax isn''t obvious to me. Any help.

Cheers

Neil

i am pretty far from knowing much about Direct3D, but i think that LPDIRECT3DDEVICE is a pointer (it''s that hungarian notation or whatever... LP = long pointer). so, you are just returning (or passing around, or copying) a pointer.
i''m fairly new to c++ also, but they might be able to mess with the device''s internal members because of this (device->messMeUp(void)). on this one, though, i''m not sure, so hopefully someone who is knowledgable will tell me to shut up and give you a complete answer.

--- krez (krezisback@aol.com)

Thanx for the input. For those not in the know
an LPDIRECT3DDEVICE is a pointer to a Direct3DDevice object.

If i was to pass back a de-referenced instance of the object it could be incredibly slow - also I don''t think that the Model class could use it then as it''s NOT the original object (it''s just a copy of it). I''m not going to make Device public (the thought never crossed my mind (honest)) but passing back a pointer to the instance of that object just seems ''dangerous'' and produces unreadble code. I have a lttle knowledge of friends (where a stated object has access to another objects private methods and variables), but i don''t actually knw how to use them.

the code I have seen looks a little like this

class D3D
{
private:
friend LPDIRECT3DDEVICE Device;
:
:
public:
:
:
};

BUT how does the compiler know what the LPDIRECT3DDEVICE is the friend of?

Cheers again

and thanks for the views even though i''m not quite there yet you have at least got rid of some possibilities (and made me look up a couple of things - something we should all do more before asking silly questions)

Neil

you can declare a function outside the class with the friend keyword:

    class FooClass  {  private:    int someVar, otherVar;    :    :  public:    friend int DaFunction(FooClass);    :    :  };::int DaFunction(FooClass Bah)  {  return Bah.someVar;  };  you can also make a class a friend of another class, so the latter can access the private stuff in the former:      class FooClass;class BahClass  {  private:    int thisVar, thatVar;  public:    int UseMyFriend(FooClass);  };int BahClass::UseMyFriend(FooClass Foo)  {  return Foo.someVar;  };class FooClass  {  private:    int someVar, otherVar;  public:    friend class BahClass;  };    

so basically, you do not declare the LPDIRECT3DDEVICE as a friend, you declare the function (or class) that can use it as a friend (in the public part of the class).

--- krez (krezisback@aol.com)

Edited by - krez on November 19, 2001 7:16:42 PM

Cheers Krez - I understand it now (at least what you wrote).
Just wanted to say thanks - i''m going to do it this afternoon

Cheers

Neil