# How to center a circle node on the terminal payoff value?

I am trying to draw a "not allowed" (big X) or "crossed out" (circle with slash) sign on some of the leaves as shown below:

Code:

\documentclass[12pt]{article}
\usepackage{istgame}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows.meta, positioning}

\begin{document}
\begin{center}
\begin{istgame}
\setistNewNodeStyle{max}
[regular polygon, regular polygon sides = 3]{1.5cm}
\setistNewNodeStyle{min}
[regular polygon, regular polygon sides = 3, shape border rotate = 180]{1.5cm}
\setistNewNodeStyle{chance}
[circle]{1.2cm}
%\xtShowTerminalNodes[box node, minimum size = 1cm]
\def\distFactor{20};
\xtdistance{\distFactor mm}{4*\distFactor mm}
\setxtarrowtips[blue, thick]
\istroot(0)[max]<center, blue>{1.5}
\istb[blue, ->-] \istb \endist
\xtdistance{\distFactor mm}{2*\distFactor mm}
\istroot(1)(0-1)[chance]<center, purple>{1.5}
\istb{0.5}[al] \istb{0.5}[ar] \endist
\istroot(2)(0-2)[chance]<center, purple>{$\leq 1$}
\istb{0.5}[al] \istb{0.5}[ar] \endist
\xtdistance{\distFactor mm}{\distFactor mm}
\istroot(3)(1-1)[min]<center, red>{2}
\istb{}{2} \istb{}{2} \endist
\istroot(4)(1-2)[min]<center, red>{1}
\istb{}{1} \istb{}{2} \endist
\istroot(5)(2-1)[min]<center, red>{0}
\istb{}{0} \istb{}{2} \endist
\istroot(6)(2-2)[min]
\istb{}{-1} \istb{}{0} \endist
\draw ([yshift = -5pt]5-2) circle (3mm);
\end{istgame}
\end{center}
\end{document}


Output:

Is there a way to draw either the X or the not allowed circular sign such that it is centered with the number on the leaf?

You can add a circle by telling istgame that this is to be circle node. And you can define a style for a crossed out circle. (A path picture would draw these on the background, which does not look good for colored texts, so I use append after command.) To make this work you then only have to say

\istb{}{2}[[ccross]below]


\istb{}{2}


Result:

\documentclass[12pt]{article}
\usepackage{geometry}
\usepackage{istgame}
\tikzset{ccross/.style={circle,draw,yshift=2pt,
append after command={
(\tikzlastnode.south west) edge[thick] (\tikzlastnode.north east)
(\tikzlastnode.south east) edge[thick] (\tikzlastnode.north west)
}}}
\begin{document}
\begin{center}
\begin{istgame}
\setistNewNodeStyle{max}
[regular polygon, regular polygon sides = 3]{1.5cm}
\setistNewNodeStyle{min}
[regular polygon, regular polygon sides = 3, shape border rotate = 180]{1.5cm}
\setistNewNodeStyle{chance}
[circle]{1.2cm}
%\xtShowTerminalNodes[box node, minimum size = 1cm]
\def\distFactor{20};
\xtdistance{\distFactor mm}{4*\distFactor mm}
\setxtarrowtips[blue, thick]
\istroot(0)[max]<center, blue>{1.5}
\istb[blue, ->-] \istb \endist
\xtdistance{\distFactor mm}{2*\distFactor mm}
\istroot(1)(0-1)[chance]<center, purple>{1.5}
\istb{0.5}[al] \istb{0.5}[ar] \endist
\istroot(2)(0-2)[chance]<center, purple>{$\leq 1$}
\istb{0.5}[al] \istb{0.5}[ar] \endist
\xtdistance{\distFactor mm}{\distFactor mm}
\istroot(3)(1-1)[min]<center, red>{2}
\istb{}{2} \istb{}{2} \endist
\istroot(4)(1-2)[min]<center, red>{1}
\istb{}{1} \istb{}{2} \endist
\istroot(5)(2-1)[min]<center, red>{0}
\istb{}{0} \istb{}{2}[[ccross]below] \endist
\istroot(6)(2-2)[min]
\istb{}{-1} \istb{}{0} \endist
\end{istgame}
\end{center}
\end{document}


• Got it. Actually, is there a way that this circle can be drawn such that it iss both centered across the 2 and that the circle’s edge touches the line? – Superman Apr 26 '20 at 4:05
• @Superman Sure, changed that. – user194703 Apr 26 '20 at 4:08