[Tex/LaTex] tikz: sloped text orientation

tikz-pgf

How do I ensure that Text 3 (as well as Text 1') has the same orientation as Text 1 and Text 2?

I want one turn of my head to be sufficient to be able to read the text.

Minimal example:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[->, node distance=3cm, every node/.style={sloped},]
    \node (a)                    {a};
    \node (c) [below right of=a] {c};
    \node (b) [below left  of=c] {b};
    \path (a) [bend right] edge node [above] {Text 1}  (b)
          (b) [bend right] edge node [above] {Text 1'} (a)
          (b) [bend right] edge node [above] {Text 2}  (c)
          (a) [bend left]  edge node [above] {Text 3}  (c);
\end{tikzpicture}
\end{document}

Updated example

Best Answer

The text labels can be rotated:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[->, node distance=3cm, every node/.style={sloped},]
    \node (a)                    {a};
    \node (c) [below right of=a] {c};
    \node (b) [below left  of=c] {b};
    \path (a) [bend right] edge node [above] {Text 1}  (b)
          (b) [bend right] edge node [above, rotate=180] {Text 1'} (a)
          (b) [bend right] edge node [above] {Text 2}  (c)
          (a) [bend left]  edge node [above, rotate=180] {Text 3}  (c);
\end{tikzpicture}
\end{document}

Result

This fixes the issue with Text 1'. The other case Text 3 is now upside-down, much less readable IMHO, see my comment to the question.

A variation with less slopes, where the labels are moved a little to the arrow start points:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[->, node distance=3cm, every node/.style={sloped},]
    \node (a)                    {a};
    \node (c) [below right of=a] {c};
    \node (b) [below left  of=c] {b};
    \path (a) [bend right] edge node [above, pos=.35] {Text 1}  (b)
          (b) [bend right] edge node [above, pos=.35] {Text 1'} (a)
          (b) [bend right] edge node [above, pos=.4] {Text 2}  (c)
          (a) [bend left]  edge node [above, pos=.35] {Text 3}  (c);
\end{tikzpicture}
\end{document}

Result

IMHO, the label angles should be in the range -90° to +90° as the default behavior to avoid upside-down labels:

\documentclass[a4paper]{article}
\usepackage{textcomp}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[->, node distance=3cm, every node/.style={sloped},]
    \path
      \foreach \a in {0, 15, ..., 345} {
        (0, 0) edge node[above, pos=.8]{\color{blue}\a\textdegree} (\a:4cm)
      }
    ;
\end{tikzpicture}
\end{document}

Result

Changing the slope for Text 3 is a manual intervention. An automated solution would need general rules. If these rules require that the label orientation depends on each other, this would also add a serious complexity level, where the result is quite unclear to be an improvement at all.

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