[Freeciv-Dev] Re: RFC: new implementation of island numbering

[Raimar Falke <rf13@xxxxxxxxxxxxxxxxx>]

On Sun, Nov 10, 2002 at 03:01:10PM -0600, Mike Kaufman wrote:
> Here is an idea I have for solving several problems related to general
> improvement effects as well as PR#2238.
> 
> here I use islands and continents interchangeably.
> 
> Currently, the server and the client have different ideas as to what is a
> continent. Since the server sees the whole map, the server can determine
> precisely which tile belongs to what continent and assigns that tile a
> number. (see mapgen.c:assign_continent_numbers())
> 
> The client doesn't have the luxury of being omniscient, it can only see
> what is known. so if a nation sends out a ship exploring and runs into a
> new landmass which isn't visibly connected to the original land, it does
> not really know whether it's a different continent altogether or the same
> continent connected somewhere in the unknown part of the map. So it
> defaults to a new continent and if later it finds out they're the same,
> merges the the continent under the same number. 
> (see climisc.c:climap_renumber_continent())
> 
> This disparity has some immediate consequences, namely for trade routes and
> some effects: for trade routes, cities on different continents get a better
> deal than ones on the same continent. So if the client calculates the
> trade, it might wind up with a different answer than the server which is
> the origin of 2238. Or for island-wide effects, this behavior leads to more
> information than a client needs to have: the presence of an effect could
> tell a client about unknown terrain.
> 
> My solution to these problems is to have the server calculate all
> continents numbers, but to do so from each client's point-of-view. So
> instead of saving these numbers in tile->continent, they will be in
> player_tile->continent. That way, for you, the server and you have the same
> idea of geography.

For clarity: Mike want that the effects (traderoutes for example) are
calculated according to the knowledge of the client.

> Davide has raised a concern that the new behavior is exploitable in the
> following way:
> 
>    oooooo
>   oo####oooo
> oooLL###LLooo
> oooCLL##LLCooo
> ooooLL##LLoooo
> oooooo###ooooo
> ooooooooooooo
> 
> o = ocean
> # = unknown
> L = land
> C = a city
> 
> if you found two cities as so and create a trade route between them, you
> will get the benefit of a trade route between separate continents, even if
> you're reasonably sure that the two cities are sitting on the same
> continent. That's true, but I contend that this is an unusual strategy, one
> that takes more work than gives benefit, since if you uncover any of the
> unknown your benefit goes away, and it's potentially dangerous to have that
> situation for trade benefit, and you _don't_really_know_ if these cities are 
> actually on the same continent. In short, I don't think that this is a good
> enough reason not to do this.
> 
> The only potential problem I see in implementing this is the coordination of
> continent numbers between players. This leads to a couple of odd effects: a
> trade route between two nations may yield different amounts of trade for
> each nation: 

> scenario: player A know that his city and B's city are on the same 
> continent. B doesn't know this. When the trade route is created, A
> gets less trade than B does. A solution which I think is fine is that a
> trade route will reveal the continent which the city is on. In that case,
> when the trade route is created, ther server will inform B that A's city is
> on the same continent. What should happen if neither know? Should they find
> out or does the server act as is they are on separate continents. I prefer
> the latter.

Currently the player get the tile_trade of the other city.

> scenario: A has discovered all of continent 1. B has two colonies on
> continent 1, but he doesn't know that they are the same continent, so he
> labels them 2 and 3. A sees both of B's colonies. B sees that one of his
> colonies (on 2) is on the same continent as A's city Rome. Now: A builds an
> improvement in Rome that delivers an island-wide effect. Question: should
> B see this effect on continents 2 only or should he see it on 3 as well?
> After all, A sees 3 in on the same island, he expects that the effect is
> affecting B's cities/units/etc on that island. I don't know about this one.

> Interesting: should mere knowledge of geography or lack thereof be a
> deciding factor in whether an effect works?

Geography as a tech?

        Raimar

-- 
 email: rf13@xxxxxxxxxxxxxxxxx
 1 + 1 = 3, for large values of 1