Re: [Bug-gnubg] A question - Which die is still available during a move? - and a request

[Jim Segrave]

On Mon 10 Feb 2003 (23:51 +0100), Holger wrote:
> On Mon, 10 Feb 2003 19:11:38 +0100, Jim Segrave wrote:
> > On Mon 10 Feb 2003 (17:57 +0100), Holger wrote:
> > > I'm trying to write a feature that helps users new to backgammon by
> > > indicating the possible target points for a move.
> > > 
> > > What I still need to know is whether there has been moved already a 
> > > chequer
> > > and with which die. Are there any variables (or functions) that hold
> > > information about which die/dice were already used and which are still 
> > > available
> > > during a move? It should be accessible from within board_pointer() in 
> > > gtkboard.c.
> > > I hope that some information about this is already kept, else I'd need to
> > > add some bookkeeping logic.
> > 
> > Hmm - you don't ask much, do you? :-)
> 
> Not that I'd thought of, at least not in the quoted part. The snipped
> rest is another issue. :-)
> Sorry, if I wasn't clear. I just wanted to ask whether there is
> already exactly what I'd need. If there isn't, bad luck for me.
> But better to ask before than doing all the work only to find that it
> had been done already. And I didn't mean to ask for a guided tour on
> how to code this. I did have some ideas.

It was a light-hearted response, although when I started writing it, I
thought the problem was likely to be very difficult to solve. It was
only when I started skimming through the gtkgame.c and gtkboard.c file
that it occurred to me that one doesn't have to keep track of which
parts of a roll have been used, a problem which gets even worse when
you consider doubles. After all, if I roll double 2 and move one
checker 4 points, have I used up one die or half of each one?

I'd noticed earlier when playing that the pip count on the board is
updated as you make each part of a move, which led me to the idea that
you could address your problem by simply comparing the number of pips
rolled to the amount of movement that's been made.

I don't think anyone is doing anything like this, but it doesn't hurt
to ask. I've been thinking about having a 'show me the possible moves'
button, but work pressures have meant that I've not done any coding on
it. 

If you subscribe to Gammonline, the on-line match there between
the subscibers and Kit Woolsey has the nice feature that you can see
the resulting positions for each of the alternatives on a roll. I'm
sometimes surprised at how much clearer the choice of plays becomes
looking at the resulting board - I suppose when I've been playing
longer I'll see this instinctively, but at the moment, I sometimes
fail to really visualise the resulting position after a move. If you
are doing something along this line, please keep the list informed, as
there would be no point in two people doing the sme thing.

> > But you might take a look at the pip counts. If you have the pip count
> > before a roll, then as chequers are moved (or put back), the count
> > changes to reflect what's been used. From that, you can determine if
> > any move has been made and if there's any unused movement left in the
> > dice (although it won't tell you that you have no further legal moves
> > left). This also works with doubles. 
> > 
> > Call PipCount() in eval.c just after the player rolls in CommandRoll()
> > and save it somewhere. Anytime you need to know if there's anything
> > used/left to play, call PipCount() again and compare the values.
> 
> Thank you for your hints.
> 
> Regards,
> 
>       Holger
> 
> 
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-- 
Jim Segrave           address@hidden