Connect two path without knowing the distance between them

Question

Considering the following picture:

I would like to connect the two blue paths in order to obtain the red path like in the following picture:

But I would like a solution where I don't have to know the horizontal length of the red path, so Tikz will automatically calculate the good length instead of me.

MWE

I tried something with coordinates but I obtain this result (I'm not able to "shift" the coordinates (A) and (B) vertically):

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}
\newcommand*{\myDistance}{1}%
\begin{document}
    \begin{tikzpicture}
        % Preliminary node positionning
        \draw (0,0) node[rectangle,draw,minimum width=\myDistance] (Nod0) {Node 0}%
        ($ (Nod0.north west)!0.2\myDistance!(Nod0.north east) $) -- ++(0,2*\myDistance)%
        -- ++(\myDistance,0)%
        node[rectangle,draw,minimum width=\myDistance cm,anchor=west] (Nod1) {Node 1}%
        (Nod1.east) -- ++(\myDistance,0)%
        node[rectangle,draw,minimum width=\myDistance cm,anchor=west] (Nod2) {Node 2}%
        ;%
    % Two paths to connect
    \draw[blue] ($ (Nod0.north west)!0.8\myDistance!(Nod0.north east) $) --  ++(0,\myDistance);%
    \draw[blue] ($ (Nod1) !.5! (Nod2) $) -- ++(0,-\myDistance);%

    \coordinate (A) at ($ (Nod0.north west)!0.8\myDistance!(Nod0.north east) $)  +(0,\myDistance);
    \coordinate (B) at ($ (Nod1) !.5! (Nod2) $) +(0,-\myDistance);%

     \draw[red] (A) -- (B);%
\end{tikzpicture}

\end{document}

Why I don't want "absolute coordinates" ?

Because I want this graph to be easily modifiable, for example if I want to change the vertical and horizontal distance between Node 0 and Node 1, I just have to change the \myDistance value and everything will be automatically adapted, no need to manually repositioning the blue paths for example because everything is positioned relatively to Node 0.

The +(…) isn't part of the coordinate specification, it's just a move to. You'll need to pull that into the coordinate specification of the coordinate. For example ($ (Nod1) !.5! (Nod2) + (0,-\myDistance) $). Though, as you are already at these points in the previous paths, just defining the coordinates there is much easier. — Qrrbrbirlbel, Feb 24 '23 at 08:03
You might be interested in the path operation |- and -| as well as something like |-|. — Qrrbrbirlbel, Feb 24 '23 at 08:38
'|-|' is a very elegant solution thank you. I think I will use this one. BTW, I was not able to use '\usepackage{tikz-ext}' after manual installation on Miktex (Miktex can't find the .sty so I got an error when compiling) but I am able to load the 'ext.paths.ortho' library now (after manual installation of tikz-ext on Miktex) so it works fine! Also, I assume that the package tikz-ext should be loaded after the tikz package but it's not mentioned on the manual. Thank you very much again! — zetyty, Feb 24 '23 at 09:05
tikz-ext isn't a LaTeX package, it's a CTAN/TeXLive/MikTeX package (I don't like it either). You just need to load the library \usetikzlibrary{ext.paths.portho}. — Qrrbrbirlbel, Feb 24 '23 at 09:13

score 2 · Accepted Answer · answered Feb 24 '23 at 07:40

Just define two coordinates at the end of the blue paths, something like this:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}
\newcommand*{\myDistance}{1}%
\begin{document}
    \begin{tikzpicture}
        % Preliminary node positionning
        \draw (0,0) node[rectangle,draw,minimum width=\myDistance] (Nod0) {Node 0}%
        ($ (Nod0.north west)!0.2\myDistance!(Nod0.north east) $) -- ++(0,2*\myDistance)%
        -- ++(\myDistance,0)%
        node[rectangle,draw,minimum width=\myDistance cm,anchor=west] (Nod1) {Node 1}%
        (Nod1.east) -- ++(\myDistance,0)%
        node[rectangle,draw,minimum width=\myDistance cm,anchor=west] (Nod2) {Node 2}%
        ;%
    % Two paths to connect
    \draw[blue] ($ (Nod0.north west)!0.8\myDistance!(Nod0.north east) $) --  ++(0,\myDistance) coordinate (A);% &lt;----
    \draw[blue] ($ (Nod1) !.5! (Nod2) $) -- ++(0,-\myDistance) coordinate (B);% &lt;----


%        \coordinate (A) at ($ (Nod0.north west)!0.8\myDistance!(Nod0.north east) $)  +(0,\myDistance);
%        \coordinate (B) at ($ (Nod1) !.5! (Nod2) $) +(0,-\myDistance);%
     \draw[red] (A) -- (B);%
\end{tikzpicture}

\end{document}

Connect two path without knowing the distance between them

MWE

Why I don't want "absolute coordinates" ?

1 Answers1