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Is it possible to define a tikz style to access the background layer by adding a style option to the node instead of having to put the entire node inside the environment? Here is an example code:

\documentclass[tikz]{standalone}

\usepackage{tikz}    
\usetikzlibrary{backgrounds}

\begin{document}

\pgfdeclarelayer{bg}
\pgfsetlayers{bg,main}

\tikzset{
  background/.style={%
    execute at begin node={\begin{pgfonlayer}{bg}},
    execute at end node={\end{pgfonlayer}}
  }
}

\begin{tikzpicture}

\draw[thick,red] (-1,0) -- (1,0);

\begin{pgfonlayer}{bg}
\node[circle,fill=blue,label={blue node behind red line, good}] at (0,0){};
\end{pgfonlayer}

\draw[thick,red] (-1,-1) -- (1,-1);
\node[circle,fill=blue,background,label={blue node above red line, bad}] at (0,-1){};

\end{tikzpicture}

\end{document}

As you see in my example, I already tried to add a custom style but with no effect. Honestly, I do not really understand how to define new styles and this is more the result of copy-pasting, so it might be pointing in a totally wrong direction.

3
  • 1
    Related, or even duplicate(s): tex.stackexchange.com/questions/20425/z-level-in-tikz tex.stackexchange.com/questions/416792 Commented Mar 8, 2018 at 13:24
  • I did not know about this question. Thanks! I think that with this approach you can define the relative position while drawing a path. I am looking for a way to access the background layer. Meaning: you have an independent \draw and \node[background] command, not \draw ... node[behind path]
    – BR123
    Commented Mar 8, 2018 at 14:04
  • I just realized that there are two questions posted. I was referring to tex.stackexchange.com/questions/416792. But tex.stackexchange.com/questions/20425/z-level-in-tikz seems to go in the right direction and I am currently checking it out. Thank you!
    – BR123
    Commented Mar 8, 2018 at 14:35

1 Answer 1

3

Thanks to the comment by Torbjørn T. and Loop Space's answer (https://tex.stackexchange.com/a/20426) I was able to find a correctly working version:

\documentclass[tikz]{standalone}

\pgfdeclarelayer{bg}
\pgfdeclarelayer{bbg}
\pgfsetlayers{bbg,bg,main}

%%% see https://tex.stackexchange.com/a/20426
\makeatletter
\pgfkeys{%
  /tikz/on layer/.code={
    \pgfonlayer{#1}\begingroup
    \aftergroup\endpgfonlayer
    \aftergroup\endgroup
  },
  /tikz/node on layer/.code={
    \gdef\node@@on@layer{%
      \setbox\tikz@tempbox=\hbox\bgroup\pgfonlayer{#1}\unhbox\tikz@tempbox\endpgfonlayer\egroup}
    \aftergroup\node@on@layer
  },
  /tikz/end node on layer/.code={
    \endpgfonlayer\endgroup\endgroup
  }
}
\def\node@on@layer{\aftergroup\node@@on@layer}
\makeatother
%%%

\begin{document}   

\begin{tikzpicture}

\draw[thick,red] (-1,0) -- (1,0);

\begin{pgfonlayer}{bg}
\node[circle,fill=blue,label={blue node behind red line, good}] at (0,0){};
\end{pgfonlayer}
\begin{pgfonlayer}{bbg}
\draw[thick,black] (-1,-0.1) -- (1,-0.1);
\end{pgfonlayer}

\draw[thick,red] (-1,-1) -- (1,-1);
\node[circle,fill=blue,node on layer=bg,label={blue node above red line, bad}] at (0,-1){};
\draw[thick,black,on layer=bbg] (-1,-1.1) -- (1,-1.1);

\end{tikzpicture}

\end{document}

enter image description here

Note: I added a black line to show the different syntax for \node[node on layer=...] and \draw[on layer=...].

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