TikZ Arrows – How to Decorate Path with Arrows at Nodes

arrowsdecorationspathstikz-pgf

Standalone example:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes}

\begin{document}
\begin{tikzpicture}
  \draw[black, very thick] plot[smooth] coordinates {(4,1) (2,2) (1,3) (2,4) (4,3)};

  \node[fill=green!60, inner sep=3pt, circle, draw] at (4, 1) {};
  \node[fill=green!60, inner sep=3pt, circle, draw] at (2, 2) {};
  \node[fill=green!60, inner sep=3pt, circle, draw] at (1, 3) {};
  \node[fill=green!60, inner sep=3pt, circle, draw] at (2, 4) {};
  \node[fill=green!60, inner sep=3pt, circle, draw] at (4, 3) {};
\end{tikzpicture}
\end{document}

Result:

enter image description here

What I want:

enter image description here

I like to have arrows before each node point at the node on all nodes in the path.
How do I achieve this?

Best Answer

Based on my own answer to this question, I got the following result:

arrow before nodes

Positioning of the arrows is done automatically according to the list of points that appears at the beginning of the code. Here we go:

\documentclass{standalone}

\usepackage{etoolbox}

\usepackage{tikz}
\usetikzlibrary{shapes}
\usetikzlibrary{intersections}
\usetikzlibrary{decorations.markings}

\newcounter{counter}
\newcommand\getpoint[1]{\csuse{point#1}}
\def\pointlist{}
\newcommand\setpoint[2]{
    \node (point#1) at #2 {};
    \csxdef{point#1}{#2} 
    \edef\pointlist{\pointlist \getpoint{#1}}
}
\newcommand\addpoint[1]{\stepcounter{counter} \setpoint{\thecounter}{#1}}

\newcounter{anothercounter}
\newcommand\getanotherpoint[1]{\csuse{anotherpoint#1}}
\def\anotherpointlist{}
\newcommand\setanotherpoint[2]{
    \csxdef{anotherpoint#1}{#2} 
    \edef\anotherpointlist{\anotherpointlist \getanotherpoint{#1}}
}
\newcommand\addanotherpoint[1]{\stepcounter{anothercounter} \setpoint{\theanothercounter}{#1}}

\begin{document}
    \begin{tikzpicture}

        \addpoint{(4,1)}
        \addpoint{(2,2)}
        \addpoint{(1,3)}
        \addpoint{(2,4)}
        \addpoint{(4,3)}

        \draw [name path = curve 1, black, very thick] plot [smooth] coordinates {\pointlist};
        \path [name intersections={of=curve 1 and curve 1, name=i, total=\t, sort by = curve 1}] node {\xdef\totalone{\t}};

        \edef\mypath{}
        \pgfmathsetmacro{\lastbutone}{\totalone - 1}
        \foreach \k in {1, ..., \lastbutone}
        {
            \xdef\mypath{\mypath (i-\k) -- }
        }
        \edef\mypath{\mypath (i-\totalone)}

        \newdimen\xone
        \newdimen\yone
        \newdimen\xtwo
        \newdimen\ytwo

        \foreach \q in {1, ..., \thecounter}
        {
            \pgfextractx{\xtwo}{\pgfpointanchor{point\q}{center}}
            \pgfextracty{\ytwo}{\pgfpointanchor{point\q}{center}}

            \foreach \p in {1, ..., \totalone}
            {
                \pgfextractx{\xone}{\pgfpointanchor{i-\p}{center}}
                \pgfextracty{\yone}{\pgfpointanchor{i-\p}{center}}

                \ifboolexpr{
                    test {\ifdimless{\xtwo - 0.6pt}{\xone}} and test {\ifdimless{\xone}{\xtwo + 0.6pt}}
                    and
                    test {\ifdimless{\ytwo - 0.6pt}{\yone}} and test {\ifdimless{\yone}{\ytwo + 0.6pt}}
                }{
                    \setanotherpoint{\q}{\p}
                }{
                }
            }
        }

        \foreach \k in {1, ..., \thecounter}
        {
            \node [
                circle
                , fill = green!60
                , inner sep = 3pt
            ] (thepoint \k) at (i-\getanotherpoint{\k}) {};
        }

        \foreach \k in {2, ..., \thecounter}
        {
            \pgfmathtruncatemacro{\lastpoint}{\getanotherpoint{\k} - 5}
            \draw [decorate, decoration = {markings, mark = at position -0.01pt with {
                \node [
                    single arrow
                    , fill = red
                    , anchor = east
                    , minimum size = 2mm
                    , inner sep = 1pt
                    , single arrow head extend = 2pt
                    , transform shape
                ]{};
            }}] (i-\lastpoint) -- (thepoint \k) {};
        }
    \end{tikzpicture}
\end{document}

EDIT

OBS: I changed the style of the arrow just to be more like the provided example.

Well, just to complete my answer, now I will give a little more detail. Tripplet said there was a space between the arrow and cículo and he was right, as can be seen here:

Separation between circle and arrow

The distance between the circle and the arrow was given by the contour line, which was not being drawn. This is easily fixed as you can see:

\foreach \k in {1, ..., \thecounter} {
    \node [
        circle
        , draw = green      % added
        , fill = green!50
        , inner sep = 3pt
    ] (thepoint \k) at (i-\getanotherpoint{\k}) {};
}

And the result is

Circle with border drawn

But, if desired the arrow gets further into the circle, one can make the following changes:

\foreach \k in {1, ..., \thecounter} {
    \node [
        circle
        , inner sep = 2.75pt
    ] (thepoint \k) at (i-\getanotherpoint{\k}) {};
    \node [
        circle
        , draw = green
        , fill = green!50
        , inner sep = 3pt
    ] at (i-\getanotherpoint{\k}) {};
}

And you will get:

Arrow futher into circle

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