Re: Where did all the ...

From: Enno Rehling <enno@despammed.com>

Date: Sat, 03 Jul 2004 15:45:47 +0000

Lemming wrote:
> As an illustration of some of the problems I'm thinking about,
> consider the question "what is a container"?

I think you're over-generalizing. Do you want to make a game, or do you
want to write an engine to make an arbitrary game? Adn even if it's the
latter, you're still better off not gernealizing too much.

One of the early problems of Anarchy Online (a popular MMORPG I used to
work on) was that every item was a full-blown object. At some point
during the development, every item had its own entry in the database,
you could drop it anywhere in the world because it had location, and so
on. Your example with the bullets reminds me a lot of the game at that
point.

And of course, performance was dreadful. And changing this was a
herculean task (Terje, if you ever read this, I'm glad I wasn't the one
doing it).
In the end we decided that items had very little data that changes, and
for each kind of item had one object (in AO, we call them dynels, for
dynamic elements). Character inventories are simple list of 3-tuples
(itemtype, amount, ammunition). The latter entra is needed because
weapons with their ammunition turned out to be the only massively used
objets that have changing properties. If your system has item decay, you
may want to add that, we decided not to have it.

I'm not saying this is how you should model the items. In fact, we would
like to change this again, but in a running game that's really not
possible, and the gain wouldn't be all that great. But I'm saying that
instead of going fully generalized, think about how small you can be and
still get away with.

By the way, we still have the full-blown items - if you drop an item in
the world, the 3-tuple gets transformed into a dynel item with a
database row to represent it.

As for your ammunition problem, you can think of it as a transformation,
too. The bullet item gets transformed into a +1 increase on the
ammunition counter of the weapon and vice versa. This means that the
weapon can't automatically calculate its weight by calling
container::weight() and summing up the weight of all contained items,
but instead has to know about its ammunition property and multiply with
the weight of the type - in short, you have to do some extra work for
each of those special cases - but it's worth it, and with proper testing
the extra code for well-chosen lack of generalization isn't a big issue.

My real advice though is to design the game you want to make first. What
should people be able to do in your world, what's the important aspects,
what's nice to have? We programmer type people like to think in cool
object hierarchies first, and then figure out at some point that all the
nice very general things we made are used in exactly one way by the
game, which could have been implemented in 10% of the time if we'd known
it was the only thing our system had to do.

Enno.
--
Enno Rehling, Lead Programmer Funcom Oslo AS
http://www.funcom.com/

References

Re: Where did all the ...
Lemming <thiswillbounce@bumblbee.demon.co.uk>
Sat, 03 Jul 2004 14:06:31 +0000
Where did all the ...
Lemming <thiswillbounce@bumblbee.demon.co.uk>
Wed, 30 Jun 2004 22:26:01 +0000
Re: Where did all the ...
Hugh Bayer <hugh@bigspider.net>
Thu, 01 Jul 2004 05:29:14 +0000
Re: Where did all the ...
Lemming <thiswillbounce@bumblbee.demon.co.uk>
Thu, 01 Jul 2004 22:33:19 +0000
Re: Where did all the ...
lindahl@pbm.com (Greg Lindahl)
Sat, 03 Jul 2004 04:04:03 +0000

Referenced By

Re: Where did all the ...
Lemming <thiswillbounce@bumblbee.demon.co.uk>
Sat, 03 Jul 2004 14:06:31 +0000
Where did all the ...
Lemming <thiswillbounce@bumblbee.demon.co.uk>
Wed, 30 Jun 2004 22:26:01 +0000
Re: Where did all the ...
Hugh Bayer <hugh@bigspider.net>
Thu, 01 Jul 2004 05:29:14 +0000
Re: Where did all the ...
Lemming <thiswillbounce@bumblbee.demon.co.uk>
Thu, 01 Jul 2004 22:33:19 +0000
Re: Where did all the ...
lindahl@pbm.com (Greg Lindahl)
Sat, 03 Jul 2004 04:04:03 +0000