[Tex/LaTex] How to build parallel paths between nodes

tikz-pgf

I want to create a figure with TikZ:

Wanted result

I tried first with the following code (remark: Complete MWE on bottom):

\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3] (A) |-( B);
\end{tikzpicture}

enter image description here

I created the two nodes A and B and draw the two pathes between them.
But the 2nd one overwrites the first.

Then I tried to shift the 2nd path, but the the starting and end point are also shifted:

\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3,transform canvas={shift={(-0.2,-0.2)}}] (A) |-( B);  %   shift complete path
\end{tikzpicture}

enter image description here

Then I tried to modify the start and end point with degrees (example now with three lines):

\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3] (A.80) |-( B.190);  %set target with angle
\path [draw,green, line width=3] (A.70) |-( B.200); %set target with angle
\end{tikzpicture}

This looks good (see my first image), but it is try and error to get the right degrees.
I the node shape changes, the distance between two pathes changes and I have to look for another degree.

\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{5cm}}; %modified node
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3] (A.80) |-( B.190);  %set target with angle
\path [draw,green, line width=3] (A.70) |-( B.200); %set target with angle
\end{tikzpicture}

enter image description here

My last attempt was using an offset for start and end position:

\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3]  (A) |-( B);
\path [draw,blue, line width=3] (A.north)+(0.2,0) |-( B.west)+(0,-0.2);
\end{tikzpicture}

enter image description here

To use the offset I must decide the start orientation (north, west…).
And in my example the starting point is ok, but the 2nd part of the path is not shifted.

I also found TikZ parallel Edges between Nodes,
but I found now way to use it.

Is there an easier way to create parallel pathes? I don't want to need try and error methods to find the correct positions. My last try with the offset seems to be the logical version, but there is a problem with the end position.

Heres my MWE:

\documentclass[]{scrartcl}

\usepackage{tikz}
% ----------------------------------------------------------------
\begin{document}

\tikzstyle{block} = [draw=black,very thick, rectangle, rounded corners]

\section{Problem: Pathes are overwritten}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3] (A) |-( B);
\end{tikzpicture}

\section{Shift path}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3,transform canvas={shift={(-0.2,-0.2)}}] (A) |-( B);  %   shift complete path
\end{tikzpicture}

\section{Set point with degrees}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3] (A.80) |-( B.190);  %set target with angle
\path [draw,green, line width=3] (A.70) |-( B.200); %set target with angle
\end{tikzpicture}

\subsection{But with other nodes}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{5cm}}; %modified node
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3] (A) |-( B);
\path [draw,blue, line width=3] (A.80) |-( B.190);  %set target with angle
\path [draw,green, line width=3] (A.70) |-( B.200); %set target with angle
\end{tikzpicture}

\section{Use offsets}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};

\path [draw,red, line width=3]  (A) |-( B);
\path [draw,blue, line width=3] (A.north)+(0.2,0) |- ( B.west)+(0,-0.2);
\end{tikzpicture}

\end{document}
% ----------------------------------------------------------------

Best Answer

Here are two ways to do this. The first uses an auxiliary node (C), as I was not able to group the calculation of coordinates. The second uses the calc package and does the computation in place. Color and distance are given in the foreach loop as pairs, so you have control where to place all lines.

\documentclass[]{scrartcl}

\usepackage{tikz}
\usetikzlibrary{calc}
% ----------------------------------------------------------------
\begin{document}
\tikzstyle{block} = [draw=black,very thick, rectangle, rounded corners]  
\section{Solution: shift lines with extra coordinate}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};
\foreach \s/\col in {0/red, 0.2/blue, 0.4/green}{
  \coordinate[yshift=-\s cm] (C) at (B.west);
  \path [draw,\col, line width=2] (A.north)+(\s cm,0) |- (C);
}
\end{tikzpicture}

\section{Solution: shift lines using calc package}
\begin{tikzpicture}
\node [block] (A) at (0,0) {\rule{2cm}{2cm}};
\node [block] (B) at (5,5) {\rule{2cm}{2cm}};
\foreach \s/\col in {0/red, 0.2/blue, 0.4/green}{
  \path [draw,\col, line width=2] (A.north)+(\s cm,0) |- ($(B.west)-(0,\s cm)$);
}
\end{tikzpicture}
\end{document}

If you want the lines centered just use in foreach \foreach \s/\col in {-0.2/red, 0/blue, 0.2/green}{...}

enter image description here

Related Solutions

[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)

[Tex/LaTex] How to define the default vertical distance between nodes

I don't really get the question so I hope this is what you wanted. If you include a full document (such that we copy paste and see the problem on our systems) things are much more easier.

Here, you can change the default setting within a scope but your block style had a node distance which was resetting every time it is issued. I've made it 2mm such that we can see the difference easier.

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows,shapes.geometric,positioning}

\begin{document}
\begin{tikzpicture}[decision/.style={diamond, draw, text width=4.5em, text badly centered, node distance=3.5cm, inner sep=0pt},
                    block/.style   ={rectangle, draw, text width=6em, text centered, rounded corners, minimum height=4em, minimum height=2em},
                    cloud/.style   ={draw, ellipse, minimum height=2em},
                    line/.style    ={draw,-latex'},
                    node distance = 1cm, 
                    auto]
    \node [block] (1st) {1st};
    \node [block, right= of 1st]  (2nd1) {2nd1};
\begin{scope}[node distance=2mm and 10mm]%Here we change it for everything inside this scope
    \node [block, above= of 2nd1] (2nd2) {2nd2};
    \node [block, below= of 2nd1] (2nd3) {2nd3};
    \node [block, right= of 2nd1] (3rd1) {3rd1};
    \node [block, above= of 3rd1] (3rd2) {3rd2};
    \node [block, above= of 3rd2] (3rd3) {3rd3};
\end{scope}
    \node [block, below= of 3rd1] (3rd4) {3rd4};
    \node [block, below= of 3rd4] (3rd5) {3rd5};

    \path [line] (1st) -- (2nd1);
    \path [line] (2nd1) -- (2nd2);
    \path [line] (2nd1) -- (2nd3);
    \path [line] (2nd2) -- (3rd3);
    \path [line] (2nd1) -- (3rd1);
    \path [line] (1st) -- (2nd1);
\end{tikzpicture}
\end{document}

enter image description here

Best Answer

Related Solutions

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

[Tex/LaTex] How to define the default vertical distance between nodes

Related Question