[Tex/LaTex] Draw on background layer with mutiple tikzpictures, remember picture and overlay

backgroundsoverlaystikz-pgf

I am constructing an image which consists of multiple tikzpictures (because some parts of them otherwise would interfere with other parts). I would like to place a background image behind all of them consisting of multiple nodes connecting the nodes on the main layer.
With remember picture I already can adress nodes defined in the other tikzpicture. With overlay I managed to place the tikzpicture with the background layer on top of the other tikzpicture(s).
I suspect the problem hast to do with using 'overlay'. Is there something like 'underlay'?

This is a (extremely simplified) MWE to show what I mean:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning, shapes}
\usepackage{xcolor}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

\begin{document}

\begin{tikzpicture}[remember picture]
    \node[circle, fill=blue] (circle) {Main};
    \node[circle, fill=blue, right=of circle] (circle2) {Main2};
    \node[circle, fill=blue, below right=of circle] (circle3) {Main3};
\end{tikzpicture}

\begin{tikzpicture}[remember picture, overlay]
    \begin{pgfonlayer}{background}
        \node[circle, fill=green, minimum height=1cm, below right=-5pt and -5pt of circle] (circle-bg) {BG};
    \end{pgfonlayer}

    \node[circle, fill=yellow, minimum height=1cm, below right=-5pt and -5pt of circle-bg] (circle-main) {overlay};

\end{tikzpicture}

\end{document}

I would like the green circle also be behind the blue circle.

Best Answer

It's not recommended to nest tikzpictures. As OP doesn't give too much details about why he/she wants to nest tikzpictures, I'll try to solve the example problem.

The green node is not behind the blue ones because even being placed on background layer, it's placed on the background layer of a second tikzpicture which is drawn after the first one.

As OP already provides three layers in its code: background, main and foreground, these three layers can be used to distributed all nodes on their corresponding layer.

Three blue nodes from first tikzpicture can be drawn on main layer, the green node on background and the yellow on foreground. This way we can control which part of the figure is behind/above each one, and we use only one tikzpicture.

\documentclass[border=2mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning, shapes}
%\usepackage{xcolor} %already loaded by tikz

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

\begin{document}

\begin{tikzpicture}[remember picture]
    \begin{pgfonlayer}{main}
    \node[circle, fill=blue] (circle) {Main};
    \node[circle, fill=blue, right=of circle] (circle2) {Main2};
    \node[circle, fill=blue, below right=of circle] (circle3) {Main3};
     \end{pgfonlayer}

    \begin{pgfonlayer}{background}
        \node[circle, fill=green, minimum height=1cm, below right=-5pt and -5pt of circle] (circle-bg) {BG};
     \end{pgfonlayer}

     \begin{pgfonlayer}{foreground}
    \node[circle, fill=yellow, minimum height=1cm, below right=-5pt and -5pt of circle-bg] (circle-main) {overlay};
    \end{pgfonlayer}

    \begin{pgfonlayer}{background}
       \draw (circle) to[out=240, in=180] (circle-main);
       \draw (circle-bg)--(circle2);
     \end{pgfonlayer}

\end{tikzpicture}

\end{document}

Related Solutions

[Tex/LaTex] Installing background and foreground page layers with TikZ

My approach for a similar effect. Declare the backgrounds globally for TikZ:

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

Then a command to place "markers" within normal text:

% place an inline node that is remembered for tikz
% \tikzremember{<node name>}
%   note: you have to compile twice
\newcommand{\tikzremember}[1]{{
  \tikz[remember picture,overlay]{\node (#1) at (0,11pt) { };}
}}

and in the document use it:

\tikzremember{bgstart}\lipsum*[2]\unskip\tikzremember{bgend}

Now, i have TikZ nodes with the page and can just draw with them like i want and any layer i want. For example, one your big green line:

\begin{tikzpicture}[remember picture,overlay]
\begin{pgfonlayer}{background}
\draw [green,line width=1cm] (bgstart.north east) -- (bgend.south west);
\end{pgfonlayer}{background}
\begin{pgfonlayer}{foreground}
\draw [green,line width=1cm] (bgstart.north east) -- (bgend.south west);
\end{pgfonlayer}{foreground}
\end{tikzpicture}

This technique is stolen from http://www.texample.net/tikz/examples/oxidation-and-reduction/

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

The source of the difficulty is that ellipses are constructed in a particular way in TikZ. They are paths that start from the x-axis and proceed counter-clockwise around their centre. The vast majority of the time, the exact parametrisation doesn't matter. You appear to have found the one situation where it does!

In the actual question, you only want to be able to mirror the ellipse, and so draw it starting from the negative x-axis (the title of the question suggests a more flexible approach). That's actually not too hard since we can exploit the symmetry of the ellipse. The key is to provide it with a negative x-radius, since then it will start from the negative x-axis (and proceed clockwise, but we could correct for that by negating the y-radius as well). To do this, we interrupt the call from the node shape to the drawing command and flip the sign of the x-radius. The simplest way to do this is to redefine the \pgfpathellipse macro to do the negation and then call the original macro. The following code does this.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations,shapes,decorations.markings}
\makeatletter
\let\origpgfpathellipse=\pgfpathellipse
\def\revpgfpathellipse#1#2#3{%
  #2%
  \pgf@xa=-\pgf@x
  \origpgfpathellipse{#1}{\pgfqpoint{\pgf@xa}{0pt}}{#3}}
\makeatother

\tikzset{
  reversed ellipse/.style={
    ellipse,
    reverse the ellipse%
  },
  reverse the ellipse/.code={
    \let\pgfpathellipse=\revpgfpathellipse
  }
}
\begin{document}
\begin{tikzpicture}
\node[ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,0) {hello world};

\node[reversed ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,-2) {hello world};
\end{tikzpicture}

\end{document}

Here's the result:

rotated ellipse

(the arrow got clipped, but you can see where it lies)

Best Answer

Related Solutions

[Tex/LaTex] Installing background and foreground page layers with TikZ

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

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