tikz-backgammon.sty

% Copyright 2012-2024 by Alan Munn
%
% This package may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3
% of this license or any later version.
% The latest version of this license is in
%   http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
%
% This package has the LPPL maintenance status `maintained'.
% 
% The Current Maintainer of this package is Alan Munn.
%
% This package consists of the file tikz-backgammon.sty and tikz-backgammon-dice.sty
% and documentation files tikz-backgammon.tex and tikz-backgammon.pdf
%
% Version 0.9 2024/01/20
%
%
\ProvidesPackage{tikz-backgammon}[2024/01/20 Backgammon game display using TikZ v0.9]
\RequirePackage{etoolbox}
\RequirePackage{tikz}
\usetikzlibrary{positioning,calc}
\RequirePackage{tikz-backgammon-dice} % dice code in a separate package

% Construct the board
%
% alternating colours for the board
\newcommand*{\bk@BW}{
	\pgfmathifthenelse{mod(\x,2)==0}{1}{0}\let\bk@fillstyle\pgfmathresult}
\newcommand*{\bk@WB}{
	\pgfmathifthenelse{mod(\x,2)==0}{0}{1}\let\bk@fillstyle\pgfmathresult}
% construct a  down point
\newcommand*{\bk@dpoint}{%
\bk@BW
\draw[thick,style=\bk@fillstyle]
     (\x,0) -- (\x+3/2,15) -- (\x+3,0) -- cycle; }
% construct an up point
\newcommand{\bk@upoint}{%
\bk@WB
\draw[thick,style=\bk@fillstyle]
     (\x,32) -- (\x+3/2,17) -- (\x+3,32) -- cycle; }
% set basic tikz parameters for the board points, dice, and stones;
% in order to scale text and nodes, node styles are specified 'transform shape'
%   
\tikzset{1/.style={fill=\boardblack},
				0/.style={fill=\boardwhite},
				stone/.style={transform shape,draw=black,circle,minimum size=3*\defaultxy,inner sep=0pt,font={\sffamily},text={\bk@stonetextcolor}},
				sans/.style={transform shape,font={\sffamily},inner sep=0pt,outer sep=0pt},
				white double/.style={line color=\black,text=\black},
				black double/.style={dice color=\black,text=\white},
				neutral double/.style={dice color=\black,text=\white},
				}

% initialization
% These should be made key values
% Maybe pass them as tikz options to a {game} environments
% This would be more flexible than having them as package options

\newcommand*{\black}{black} % for the stones
\newcommand*{\white}{white}
\newcommand*{\boardblack}{brown}
\newcommand*{\boardwhite}{olive!50}
\newcommand*{\barcolor}{brown}
\newcommand*{\defaultxy}{.5em}
\newlength{\betweengameskip}
\setlength{\betweengameskip}{2\baselineskip}
% initial state of the doubling cube
\newcommand*{\bk@doublestate}{neutral}
\newcommand*{\bk@doublenum}{64}
% create 24 counters for the point counts
% create 24 macros for the point state (black,white,none)
\foreach \x in {1,...,24}{
  \newcounter{bk@pt\x}
	\expandafter\gdef\csname bk@state\x\endcsname{none}
}
% create 2 counters state of the bar (we don't need a state)
% this still needs to be implemented
% do we need 2 different commands, one for within a game
% and the other for setting the board manually?
% 0 for white 1 for black
\foreach \x in {0,1}{
	\newcounter{bk@bar\x}
}

% create 2 counters and macros for the state of bearing off
% this still needs to be implemented
% this will work similarly to the bar state
% 0 for white 1 for black
\foreach \x in {0,1}{
	\newcounter{bk@off\x}
}

% Current code has only one bar state (this is wrong)
%\newcounter{bk@bar}
%\newcommand*{\bk@barstate}{none}


% some utility and debugging commands
\newcommand*\showpoint[1]{\the\csname c@bk@pt#1\endcsname}
\newcommand*\bk@setstate[2]{\expandafter\gdef\csname bk@state#1\endcsname{#2}}
\newcommand*\bk@setcount[2]{\global\csname c@bk@pt#1\endcsname #2\relax}
\newcommand*\bk@barcount[2]{\advance\csname c@bk@bar#1\endscname#2\relax}
%\newcommand*\bk@barset[2]{\expandafter\gdef\csname\bk@barstate#1\endcsname{#2}}
\newcommand*\usestate[1]{\csname bk@state#1\endcsname}

% basic command to draw the board
% all of these numbers probably shouldn't be hard coded
%
\newif\ifbk@black\bk@blacktrue % sets the view of the board
\newif\ifbk@displaydice\bk@displaydicefalse % toggle to display the dice or not
\newcommand*\bk@right{40.5}
\newcommand*\bk@left{-1.5}
\newcommand*\bk@upstart{-1.75}
\newcommand*\bk@downstart{33.75}
\newcommand*\bk@nodelabel{%
	\ifbk@black
		\bk@nodename
	\else
		\number\numexpr 25-\bk@nodename\relax
	\fi}
\newcommand*\bk@wstart{\ifbk@black\bk@downstart\else\bk@upstart\fi}
\newcommand{\bk@drawboard}{%
% draw the border and the point numbers
% the nodes are numbered internally from the point of view of black
% nodes are labelled according to the view of the person playing
% this is encoded in the conditional \ifbk@black. If this is false
% the nodes will be labelled from white's point of view.
    \draw[line width=4pt] (0,0) -- (0,32) -- (39,32) -- (39,0) -- cycle;
    \foreach \x in {1,...,6}{
    		\let\bk@nodename\x
       \node[sans] (\bk@nodename) at (\bk@left+\x*3,\bk@upstart)  {\bk@nodelabel};
        \pgfmathparse{int(\x+6)}\let\bk@nodename\pgfmathresult
        \node[sans] (\bk@nodename) at (\bk@left+\x*3+21,\bk@upstart)  {\bk@nodelabel};
        \pgfmathparse{int(\x+12)}\let\bk@nodename\pgfmathresult
        \node[sans] (\bk@nodename) at (\bk@right-\x*3,\bk@downstart)  {\bk@nodelabel};
        \pgfmathparse{int(\x+18)}\let\bk@nodename\pgfmathresult
         \node[sans] (\bk@nodename) at (\bk@right-\x*3-21,\bk@downstart)  {\bk@nodelabel};
    }
% now draw the first half points
  \foreach \x in {0,3,...,15}
     \bk@dpoint
  \foreach \x in {0,3,...,15}
     \bk@upoint
% draw the bar and set the anchors for bar and the doubling cube and dice rolls
  \draw[very thick,fill=\barcolor](18,0) -- (18,32) -- (21,32) -- (21,0) -- cycle;
  \coordinate (barcenter) at (19.5,14);
  \coordinate (whitebar) at (19.5,28);
  \coordinate (blackbar) at (19.5,4);
  \coordinate (black double) at (42, 4);
  \coordinate (white double) at (42, 28);
  \coordinate (neutral double) at (42,16);
  \coordinate (black dice) at (9,16);
  \coordinate (white dice) at (30,16);
  \coordinate (caption) at (19.5,-4);
  \coordinate (offblack) at (-4,4);
  \coordinate (offwhite) at (-4,28);
% draw the other half of the points
  \foreach \x in {21,24,...,36}
     \bk@dpoint
  \foreach \x in {21,24,...,36}
     \bk@upoint
}
%  commands to place markers on a point and set its state
%  for users to make arbitrary board configurations

% first for a black point (user command)
\newcommand{\blackpoint}[2]{%
  \bk@setstate{#1}{black}%
  \bk@setcount{#1}{#2}%
  \ignorespaces
}
% same again for a white point (this is from point in whites view)
\newcommand{\whitepoint}[2]{%
  \def\bk@tmp{\numexpr 25-#1\relax}%
  \bk@setstate{\the\bk@tmp}{white}%
  \bk@setcount{\the\bk@tmp}{#2}%
  \ignorespaces
}
% now a generic version of the command for use in displaying the board
% this is  an internal command and uses the internal point numbers
% this now correctly displays the excess number of stones on the last
% one; 
\newif\ifbk@maxstones
\newcommand{\bk@placepoint}[2]{%
	\bk@maxstonesfalse%
  \let\ptname#1%
  \def\bk@tmpb{black}%
  \ifcsstrequal{\usestate{\ptname}}{\bk@tmpb}{\let\bk@stonetextcolor\white}{\let\bk@stonetextcolor\black}
  \ifnumcomp{#2}{<}{1}%
     {}
     {\ifnumcomp{#2}{>}{5}%
     		{\gdef\bk@tmp{5}\bk@maxstonestrue\xdef\bk@tmpa{#2}}
				{\gdef\bk@tmp{#2}}
     {\pgfmathparse{ifthenelse(#1>12,"below","above")}\let\bk@pos\pgfmathresult
         \foreach \x in {1,...,\bk@tmp}
            \node[fill=\usestate{\ptname},style=stone,\bk@pos=(3*\x)-2 of \ptname]
              	{\ifbk@maxstones
									\pgfmathparse{ifthenelse(\x==5,\bk@tmpa,"")}\pgfmathresult
									\else\relax\fi};
      }}
}
% command to place stones on the bar
\newcommand{\bk@placebar}{%
\foreach \y in {0,...,1}{
	\def\bk@barcount{\the\csname c@bk@bar\y\endcsname}
	\bk@maxstonesfalse
	\ifnumcomp{\y}{=}{0}
	{\global\let\bk@stonetextcolor\black
	 \gdef\bk@stonecolor{white}
	 \gdef\bk@barpos{whitebar}
	 \gdef\bk@orient{below}}
	{\global\let\bk@stonetextcolor\white
	 \gdef\bk@stonecolor{black}
	 \gdef\bk@barpos{blackbar}
	 \gdef\bk@orient{above}}
	\ifnumcomp{\bk@barcount}{>}{3}
		{\gdef\bk@tmp{3}\bk@maxstonestrue\xdef\bk@tmpa{\bk@barcount}}
		{\gdef\bk@tmp{\bk@barcount}}
	\ifnumcomp{\bk@barcount}{>}{0}
	{\foreach \x in {1,...,\bk@tmp}
		\node[fill=\bk@stonecolor,style=stone,\bk@orient=(3*\x)-2 of \bk@barpos] {\ifbk@maxstones
									\pgfmathparse{ifthenelse(\x==3,\bk@tmpa,"")}\pgfmathresult
									\else\relax\fi};}{}}
}

% command to display borne off stones

% user command to place pieces on the bar
% syntax is \onbar{colour}{amount}
% this is the manual set command so we don't increment the counter
\newcommand*{\onbar}[2]{%
	\ifstrequal{#1}{black}
		{\setcounter{bk@bar1}{#2}}
		{\ifstrequal{#1}{white}
			{\setcounter{bk@bar0}{#2}}
			{\PackageError{tikz-backgammon}{Only 'white' or 'black' can be on the bar}{Check your spelling!}}
		}
}
% user command to set a double
% syntax is \double{<owner>}{amount}
\newcommand*{\double}[2]{%
  \def\bk@doublenum{#2}
  \ifstrequal{#1}{neutral}
     {\gdef\bk@doublestate{neutral double}}
     {\ifstrequal{#1}{white}
        {\gdef\bk@doublestate{white double}}
        {\gdef\bk@doublestate{black double}}
     }
}
% command to place the doubling cube in the correct place
\newcommand*{\bk@placedouble}{%
   \node at (\bk@doublestate) 
   {\drawdblcube[\bk@doublestate]{\bk@doublenum}};} % 
  
% command to display the dice
\newcommand*{\bk@whitedice}[2]{%
	\node at (white dice) [left=0pt] (dice) 
		{\drawdie[dot color=\black,line color=\black]{#1}};
	\node at (white dice) [right=0pt] (dice) 
		{\drawdie[dot color=\black,line color=\black]{#2}};
}
\newcommand*{\bk@blackdice}[2]{%
	\node at (black dice) [left=0pt] (dice) 
		{\drawdie[dot color=\white,dice color=\black]{#1}};
	\node at (black dice) [right=0pt] (dice) 
		{\drawdie[dot color=\white,dice color=\black]{#2}};
}
% This is an internal command to parse a dice role in the form (nm)
% into two separate parts so that the dice can be generated
\def\bk@parsedice(#1#2){\gdef\bk@dice@one{#1}\gdef\bk@dice@two{#2}}

% User commands to display a roll; roll in nm format
%
\newcommand*{\blackroll}[1]{%
	\bk@displaydicetrue
	\gdef\bk@dicestate{black}
	\bk@parsedice(#1)%
}
\newcommand*{\whiteroll}[1]{%
	\bk@displaydicetrue
	\gdef\bk@dicestate{white}
	\bk@parsedice(#1)%
}

% user command to draw a blank board
\newcommand*{\blankboard}[1][]{%
	\double{neutral}{64}
	\begin{tikzpicture}[x=\defaultxy,y=\defaultxy,#1]
		\bk@drawboard;
	\end{tikzpicture}
}

% user command to clear the board state
\newcommand*{\clearboard}{%
	\double{neutral}{64}
	\bk@displaydicefalse
	\foreach \x in {1,...,24}{\bk@setcount{\x}{0}}
	}
	

% user commands to set the caption for a board
\newcommand{\boardcaptionformat}[1]{\gdef\bk@captionformat{#1}}
\boardcaptionformat{}
\newcommand{\boardcaption}[1]{\gdef\bk@boardcaption{\bk@captionformat#1\par}}
\boardcaption{}

% command to setup the pieces for a new game without drawing anything
\newcommand*\newpieces{
	\foreach \x in {1,12,17,19}
   	{\bk@setstate{\x}{white}}
	\foreach \x in {6,8,13,24}
		{\bk@setstate{\x}{black}}
	\foreach \x in {1,24}
		{\bk@setcount{\x}{2}}
	\foreach \x in {12,19,13,6}
		{\bk@setcount{\x}{5}}
	\foreach \x in {17,8}
		{\bk@setcount{\x}{3}}
	\double{neutral}{64}
	\bk@displaydicefalse
}		

% command to set a new game (no longer displays it)  
\let\newgame=\newpieces
 
% commands to move first black, then white
% starred versions are for doubles
% This needs to be rewritten to accept 'bar' and 'off' arguments 

\newcommand\blackmove{\@ifstar\bk@blackdouble\bk@blacksingle}
\newcommand\bk@blacksingle[4]{%
	\advance\csname c@bk@pt#1\endcsname -1\relax
	\ifnumcomp{\the\csname c@bk@pt#1\endcsname}{=}{0}
		{\expandafter\gdef\csname bk@state#1\endcsname{none}}
		{\expandafter\gdef\csname bk@state#1\endcsname{black}}
	\ifnumcomp{#2}{=}{0}{}{\advance\csname c@bk@pt#2\endcsname 1\relax}
	\expandafter\gdef\csname bk@state#2\endcsname{black}
	\advance\csname c@bk@pt#3\endcsname -1\relax
	\ifnumcomp{\the\csname c@bk@pt#3\endcsname}{=}{0}
		{\expandafter\gdef\csname bk@state#1\endcsname{none}}
		{\expandafter\gdef\csname bk@state#3\endcsname{black}}
	\ifnumcomp{#4}{=}{0}{}{\advance\csname c@bk@pt#4\endcsname 1\relax}
	\expandafter\gdef\csname bk@state#4\endcsname{black}
}
\newcommand\bk@blackdouble[4]{%
	\bk@blacksingle{#1}{#2}{#1}{#2}
	\bk@blacksingle{#3}{#4}{#3}{#4}
}
% White moves are normalized so that the input is from white's point of view
% Since the point numbers internally are from black's view, we need to subtract
% each white move from 25 to calculate the correct point number for white.
% Thanks to Enrico Gregorio for help with this code
\newcommand\whitemove{\@ifstar\bk@whitedouble\bk@whitesingle}
\newcommand\bk@whitesingle[4]{
	\advance\csname c@bk@pt\number\numexpr 25-#1\relax\endcsname -1\relax
	\ifnumcomp{\the\csname c@bk@pt\number\numexpr 25-#1\relax\endcsname}{=}{0}
		{\expandafter\gdef\csname bk@state\number\numexpr 25-#1\relax\endcsname{none}}
		{\expandafter\gdef\csname bk@state\number\numexpr 25-#1\relax\endcsname{white}}
	\ifnumcomp{\numexpr 25-#2\relax}{=}{0}{}{\advance\csname c@bk@pt\number\numexpr 25-#2\relax\endcsname 1\relax}
	\expandafter\gdef\csname bk@state\number\numexpr 25-#2\relax\endcsname{white}
	\advance\csname c@bk@pt\number\numexpr 25-#3\relax\endcsname -1\relax
	\ifnumcomp{\the\csname c@bk@pt\number\numexpr 25-#3\relax\endcsname}{=}{0}
		{\expandafter\gdef\csname bk@state\number\numexpr 25-#1\relax\endcsname{none}}
		{\expandafter\gdef\csname bk@state\number\numexpr 25-#3\relax\endcsname{white}}
	\ifnumcomp{\numexpr 25-#4\relax}{=}{0}{}{\advance\csname c@bk@pt\number\numexpr 25-#4\relax\endcsname 1\relax}
	\expandafter\gdef\csname bk@state#4\endcsname{white}
}
\newcommand\bk@whitedouble[4]{%
	\bk@whitesingle{#1}{#2}{#1}{#2}
	\bk@whitesingle{#3}{#4}{#3}{#4}
}

% black and white moves using nm:to/from,to/from notation
\newcommand*{\blkmove}[1]{\bk@blkparsemove(#1)}
\newcommand*{\whtmove}[1]{\bk@whtparsemove(#1)}
\def\bk@blkparsemove(#1:#2/#3,#4/#5){\blackroll{#1}\blackmove{#2}{#3}{#4}{#5}}
\def\bk@whtparsemove(#1:#2/#3,#4/#5){\whiteroll{#1}\whitemove{#2}{#3}{#4}{#5}}

% command to display the current state of the board
\newcommand*\whiteboard{\bk@blackfalse\bk@displayboard}
\newcommand*\blackboard{\bk@blacktrue\bk@displayboard}
\newcommand{\bk@displayboard}[1][]{%
  \par\vspace{\betweengameskip}
  \begin{tikzpicture}[x=\defaultxy,y=\defaultxy,#1]
		\bk@drawboard
		\foreach \x in {1,...,24}{
 			\bk@placepoint{\x}{\the\csname c@bk@pt\x\endcsname}}
 		\bk@placedouble
		\bk@placebar
		\ifbk@displaydice
			\csname bk@\bk@dicestate dice\endcsname{\bk@dice@one}{\bk@dice@two}\fi
		\node[align=center,anchor=north,inner sep=0pt] at (caption)
				{\bk@boardcaption};
	\end{tikzpicture}
% after drawing the board we reset the caption and the dice display
	\bk@displaydicefalse
	\boardcaption{}
}
\endinput
% Still to be added:
% need commands for entering from the bar and bearing off