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[OT] game engine (as in rules not graphics)

 
 
Martin
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      12-27-2008
Hello,

I'd like to get in touch with game development a bit. I'm not talking
about graphics but rather the game rules itself. Something like
http://en.wikipedia.org/wiki/Monopoly_(game)#Rules, is there even a
general approach to that or should I just go sketch up my rules and
try to implement them. Being totally new to this topic I don't quite
now what to search for to get some decent results that let me make a
mental link between game rules and what the best practices are to
implement them in python (or any other programming language)

thanks,
martin

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Aaron Brady
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      12-28-2008
On Dec 27, 3:02*pm, Martin <(E-Mail Removed)> wrote:
> Hello,
>
> I'd like to get in touch with game development a bit. I'm not talking
> about graphics but rather the game rules itself. Something likehttp://en.wikipedia.org/wiki/Monopoly_(game)#Rules, is there even a
> general approach to that or should I just go sketch up my rules and
> try to implement them. Being totally new to this topic I don't quite
> now what to search for to get some decent results that let me make a
> mental link between game rules and what the best practices are to
> implement them in python (or any other programming language)
>
> thanks,
> martin


Not my expertise but here are my $0.02. You are looking for ways to
represent rules: buying a house is legal in such and such situation,
and the formula for calculating its price is something. You want
"predicates" such as InJail, OwnedBy, Costs.

Costs( New York Ave, 200 )
InJail( player2 )
OwnedBy( St. Charles Ave, player4 )
LegalMove( rolldie )
LegalMove( sellhouse )

There are rule-based languages out there, such as Prolog. They are
equally expressive as Python (you can write a Turing machine in them),
but they are more convenient for representing rules in a prog.
language.

Predicates are more or less equivalent to positive assertions about
something.

NewYorkAve.cost= 200
player2.injail= True...
rolldie.islegal= True

Some predicates have to be calculated, rather than stored, but Python
descriptors go easy on you for that. Someone else will have to tell
you how rule-based programming measures up against object-oriented
programming. <passes mic.>
 
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Martin
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      12-29-2008
Hi,


2008/12/29 Phil Runciman <(E-Mail Removed)>:
> See: Chris Moss, Prolog++: The Power of Object-Oriented and Logic Programming (ISBN 0201565072)
>
> This book is a pretty handy intro to an OO version Prolog produced by Logic Programming Associates.


> From: Aaron Brady [(E-Mail Removed)]
> Sent: Sunday, 28 December 2008 1:22 p.m.
> Not my expertise but here are my $0.02. You are looking for ways to represent rules: buying a house is legal in such and such situation, and the formula for calculating its price is something. You want "predicates" such as InJail, OwnedBy, Costs.
>
> Costs( New York Ave, 200 )
> InJail( player2 )
> OwnedBy( St. Charles Ave, player4 )
> LegalMove( rolldie )
> LegalMove( sellhouse )


I'm not sure I'm looking for prolog, i had an introductory course back
at the university but it didn't exactly like it. I'm after some info
how such rules would defined in python (specifically python althou
logic programming is probably the more appropriate way).

I guess I'm missing quite some basics in the design of such concepts,
I'll head back to google to find some introductory stuff now .

regards,
Martin


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Aaron Brady
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      12-29-2008
On Dec 29, 4:14*am, Martin <(E-Mail Removed)> wrote:
> Hi,
>
> 2008/12/29 Phil Runciman <(E-Mail Removed)>:
>
> > See: Chris Moss, Prolog++: The Power of Object-Oriented and Logic Programming (ISBN 0201565072)

>
> > This book is a pretty handy intro to an OO version Prolog produced by Logic Programming Associates.
> > From: Aaron Brady [(E-Mail Removed)]
> > Sent: Sunday, 28 December 2008 1:22 p.m.
> > Not my expertise but here are my $0.02. *You are looking for ways to represent rules: buying a house is legal in such and such situation, and the formula for calculating its price is something. *You want "predicates" such as InJail, OwnedBy, Costs.

>
> > Costs( New York Ave, 200 )
> > InJail( player2 )
> > OwnedBy( St. Charles Ave, player4 )
> > LegalMove( rolldie )
> > LegalMove( sellhouse )

>
> I'm not sure I'm looking for prolog, i had an introductory course back
> at the university but it didn't exactly like it. I'm after some info
> how such rules would defined in python (specifically python althou
> logic programming is probably the more appropriate way).
>
> I guess I'm missing quite some basics in the design of such concepts,
> I'll head back to google to find some introductory stuff now .

snip

It depends on what you want to do with it. Do you want to answer a
question about whether something is legal? Do you want a catalog of
legal moves? Do you want to forward-chain moves to a state? Do you
want just a representation for its own sake?

For instance, the game just started. Player 1 landed on Oriental,
bought it, and Player 2 landed in the same place. Here are the legal
possibilities.

Player 1 offers to sell Oriental to Player X.
Player X offers to buy Oriental from Player 1.
Player 1 mortgages Oriental.
Player 1 collects rent from Player 2.
Player 3 rolls dice.

Thinking aloud, I think the closest thing to predicates you'll have in
Python is to build a Relation class or use a relational database.
Some tables you might use are: Property( id, name, price, rent0houses,
rent1house, ..., numhouses, mortgaged, owner ). Player( id, location,
money ). LastMove( player.id ).

P.S. There is 'pyprolog' on sourceforge; I did not check it out.
 
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Aaron Brady
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      01-01-2009
On Dec 29 2008, 8:52*am, Aaron Brady <(E-Mail Removed)> wrote:
> On Dec 29, 4:14*am, Martin <(E-Mail Removed)> wrote:
>
> > Hi,

>
> > 2008/12/29 Phil Runciman <(E-Mail Removed)>:

>
> > > See: Chris Moss, Prolog++: The Power of Object-Oriented and Logic Programming (ISBN 0201565072)

>
> > > This book is a pretty handy intro to an OO version Prolog produced by Logic Programming Associates.
> > > From: Aaron Brady [(E-Mail Removed)]
> > > Sent: Sunday, 28 December 2008 1:22 p.m.
> > > Not my expertise but here are my $0.02. *You are looking for ways to represent rules: buying a house is legal in such and such situation, and the formula for calculating its price is something. *You want "predicates" such as InJail, OwnedBy, Costs.

>
> > > Costs( New York Ave, 200 )
> > > InJail( player2 )
> > > OwnedBy( St. Charles Ave, player4 )
> > > LegalMove( rolldie )
> > > LegalMove( sellhouse )

>
> > I'm not sure I'm looking for prolog, i had an introductory course back
> > at the university but it didn't exactly like it. I'm after some info
> > how such rules would defined in python (specifically python althou
> > logic programming is probably the more appropriate way).

>
> > I guess I'm missing quite some basics in the design of such concepts,
> > I'll head back to google to find some introductory stuff now .

>
> snip
>
> It depends on what you want to do with it. *Do you want to answer a
> question about whether something is legal? *Do you want a catalog of
> legal moves? *Do you want to forward-chain moves to a state? *Do you
> want just a representation for its own sake?
>
> For instance, the game just started. *Player 1 landed on Oriental,
> bought it, and Player 2 landed in the same place. *Here are the legal
> possibilities.
>
> Player 1 offers to sell Oriental to Player X.
> Player X offers to buy Oriental from Player 1.
> Player 1 mortgages Oriental.
> Player 1 collects rent from Player 2.
> Player 3 rolls dice.
>
> Thinking aloud, I think the closest thing to predicates you'll have in
> Python is to build a Relation class or use a relational database.
> Some tables you might use are: Property( id, name, price, rent0houses,
> rent1house, ..., numhouses, mortgaged, owner ). *Player( id, location,
> money ). *LastMove( player.id ).
>
> P.S. *There is 'pyprolog' on sourceforge; I did not check it out.


You know what I am thinking for this-- not that the OP is still
around-- is a regular expression / BNF grammar that transitions on
moves from one legal set of moves to the next. It will need some sort
of concatenation structure, since late in the game, selling each
property a player has is a legal move. Sorry for the replies to
myself.
 
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