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1 comment by Herr_Alien on Apr 26th, 2010

If you already programmed in COM, feel free to skip the article. Yep. Nothing interesting for you here.

If you're a coder that has some experience with previous game engines but you're new to Unity, then read on.

So. Two programs and a technology for software development. And a picture:COM object and interfaces

That's a COM object. Our target is "Outer Object". It imlements several interfaces, the circles labeled A, B ...

In terms of inheritance, you could do that by deriving the class describing. Now of course, there are some problems when all them interface implement a function with the same signature, say void Update(): which Update() should be called in your case? The one from A? Or B? Or C? I personally don't like C, as a vitamin at least it is sour.

This is where COM ... comes in place. In COM, if you want to implement an interface on an object, you'll get a new instance of a class. That means that somehow, in your objects, you'll have at least three class instances, one that implements the functionality of A, one for B, well, you get the point.

Why the frowned face? Oh, stupid me, I forgot something: from now on, your object is no longer an instance of one class. No. That's gone. Think of it as a collection of classes, each working together to provide functionality for one object.

Now I can hear you saying: "But what if I need to use functionality from Interface A in the implementation of Interface B? How can I reach one functionality from the other?"

In all technologies that implement an object modeling mechanism (yep, that's the OM from COM), there will always be a mechanism to go from one interface to the other. In COM, it is called "QueryInterface". In Unity, you GetComponent.

Now it makes sense. This is why the First Person Controller prefab in Unity looks like this:

Unity's fps controller

You'll see that I underlined two components (get used to the term if you plan to use Unity). If you double click them, you'll end up looking at some C# code. Each of the scripts describe a class, each having a Start() and Update() function. Several components, working to define one object.
And here's another thing about COM: you can re-use components:


The Mouse Look script is the shared component here.

That's it. Don't say I didn't warn you, if you know COM this was not a surprise.

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Post comment Comments  (10 - 20 of 28)
mrinal May 4 2010 says:

thanks for adding me as ur friend.

+1 vote     reply to comment
ElderPredator Feb 25 2010 says:

Moduri grozave ai =D, asa ti jocu in viata...tine-o tot asa ;)!!!

+1 vote     reply to comment
Herr_Alien Creator
Herr_Alien Mar 4 2010 replied:

La Master Server Patch am lucrat impreuna cu un tip din Canada, Jeff Attwood.

+1 vote   reply to comment
GokuSaiyan123 Oct 31 2009 says:

any of you play dragon ball Z for the pc can someone help me out

+1 vote     reply to comment
ninjadave Oct 3 2009 says:

I write code too.
One time it worked.

+1 vote     reply to comment
Herr_Alien Creator
Herr_Alien Oct 5 2009 replied:

Well, in my case I try to make a living through writting code, lol :)

The 'I write code' is actually related to this:

+1 vote   reply to comment
Camo_Ninja Jul 5 2009 says:

hey ya doing? I was wondering if you can help me with a little problem about the project saviour mod. I posted on the prolem in the project saviour page here on MODDB.

can you please take a look and ee if you can help me?

+1 vote     reply to comment
Play0n Apr 16 2009 says:

Thx for making AVP2 Fortress and keeping the game alive

+1 vote     reply to comment
Herr_Alien Creator
Herr_Alien Apr 16 2009 replied:

You're welcome! We have a lot of fun doing it too :)

+1 vote   reply to comment
KOM Jan 24 2009 says:

hey thanks for watching the mod

+1 vote     reply to comment
Herr_Alien Creator
Herr_Alien Jan 30 2009 replied:

You lost me a bit :)
Anyway, I really like the game, and I do enjoy modding it. As for this particular project, it was needed.

I whish you guys good luck! I will definitely play your mod when it is released.

+1 vote   reply to comment
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