[Tex/LaTex] How to draw zig zag arrows at some particular locations in tikz diagram

tikz-pgf

I want to draw a diagram like this:

enter image description here

My tikz code is as follows: 

\documentclass{article}
\usepackage{tikz}
\usepackage[margin=15mm]{geometry}
\usepackage{calc}
\usetikzlibrary{matrix,arrows}
\usetikzlibrary{positioning,arrows}
\usetikzlibrary{shapes,arrows,fit,calc,positioning,automata}

\begin{document}
\tikzstyle{int}=[draw, minimum width=3 cm, minimum height=1 cm]
\tikzstyle{init} = [pin edge={to-,thin,black}]


\begin{tikzpicture}[node distance=5cm,auto,>=latex', scale = 1, transform shape]
    \tikzstyle{line} = [draw, -latex']
    \node [int] (a) { Box1 };
    \node [int] (b) [below of=a, node distance=4 cm] {Box2};

\end{tikzpicture}

\end{document}

which outputs as follows:

enter image description here

I don't understand how to draw such arrows at correct locations in tikz. I know only how to draw at center. How can I do this?

Best Answer

In this case, the let syntax could be used, as the following example illustrates:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc,positioning}

\begin{document}

\begin{tikzpicture}
\node  (a) {A};
\node[above right=of a] (b) {B};
\draw[red,->] let \p1=(a), \p2=(b) in (a) -- (\x1,0.5*\x2) -| (b);
\end{tikzpicture}

\end{document}

enter image description here

Another possibility is to use the implicit syntax for the node coordinate system, using the name of a node together with an anchor or an angle separated by a dot as in (a.north) or (a.30); the following example uses this approach:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows,calc,positioning}

\tikzset{int/.style={draw, minimum width=3 cm, minimum height=1 cm},
init/.style={pin edge={to-,thin,black}}}

\begin{document}

\begin{tikzpicture}[node distance=1cm,auto,>=latex']
\node [int] (a) { Box1 };
\node [int] (b) [below of=a, node distance=4 cm] {Box2};
\node[above =of a.150,align=center] (aux1) {Input 1 \\ From 1};
\node[above =of a.30,align=center] (aux2) {Input 2 \\ From 2};

\draw[->] (aux1) -- ($(aux1)!.6!(a.150)$) -| (a.110);
\draw[->] (aux2) -- ($(aux2)!.6!(a.30)$) -| (a.70);
\draw[->]  (a.south) -- +(0,-0.5) -| node[fill=white,near end,align=center,xshift=-0.75cm] (aux3) {Output 1 \\ From 1} (b.150);

\node[right =of aux3,align=center,xshift=-0.75cm] (aux4) {Input 3 \\ From 3};

\draw[->] (aux4.south) -- (aux4.south|-b.north);
\draw[->] (b.230) -- +(0,-1cm) node[anchor=north] {Yes};
\draw[->] (b.310) -- +(0,-1cm) node[anchor=north] {No};
\end{tikzpicture}

\end{document}

enter image description here

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