How to use "sloped" when the x and y scales are different?

Question

In the example below, I want to align the text to the right of the tangent, as the scales are different, the tilt is wrong. I tried to use "transform shape" by the text becomes unreadable (too small), I can of course add a scale (different according to x and y) but it becomes a complicated code for not much.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary {calc}
\usepackage{SIunitx}
\begin{document}
\begin{tikzpicture}[xscale=0.15,yscale=0.4]
\draw [thin,xstep=5,ystep=1,blue,dashed] (0,0) grid (50,12);
\draw[-latex,thick] (0,0) -- (51,0) node[below]{$t$ en \si{\second}};
\draw[-latex, thick] (0,0) -- (0,13) node[above right]{$v$ en \si{\mm\per\second}};
\draw[domain=0:50] plot (\x,{8(1-exp(-\x/10))});
\draw[dashed,red,thick] (0,8)-- (50,8)node[above left]{$s_\infty=G\cdot U_0=\SI{8}{\mm/\second}$};
\draw[dashed,red,thick] (0,0) coordinate(O)-- node[sloped,above, pos=0.8]{Tangente en (0,0)}(10,8);
\draw[thick, red] (10,0) -- (10, {8(1-exp(-1))}) coordinate(T0) -- (T0-|O)node[above]{$\num{0.63}\cdot G\cdot U_O$};
\node[below] at (10,0){10};
\node[left] at (0,10){10};
\end{tikzpicture}
\end{document}

Sloped Tikz node with rotation and scale - TeX - LaTeX Stack Exchange ? — user202729, Oct 11 '21 at 08:02
The third way to solve this is by using x=0.15cm, y=0.4cm, i.e. not scaling the diagram but only the coordinate system. — Qrrbrbirlbel, Oct 21 '23 at 15:11

score 4 · Answer 1 · answered Oct 11 '21 at 08:21

One way to do it is to use a decoration:

\draw[dashed,red,thick,
    postaction={decorate},
    decoration={
        markings,
        mark=at position 1.0 with {
            \node [blue, transform shape, anchor=base, shift={(10pt,2pt)}] 
                {Tangente en (0,0)};
        },
    },
] (0,0) coordinate(O) -- (10,8);

Code:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary {calc}
\usepackage{siunitx}
\usetikzlibrary{decorations.markings}
\begin{document}
\begin{tikzpicture}[xscale=0.15,yscale=0.4]
\draw [thin,xstep=5,ystep=1,gray,dashed] (0,0) grid (50,12);
\draw[-latex,thick] (0,0) -- (51,0) node[below]{$t$ en \si{\second}};
\draw[-latex, thick] (0,0) -- (0,13) node[above right]{$v$ en \si{\mm\per\second}};
\draw[domain=0:50] plot (\x,{8(1-exp(-\x/10))});
\draw[dashed,red,thick] (0,8)-- (50,8)node[above left]{$s_\infty=G\cdot U_0=\SI{8}{\mm/\second}$};
\draw[dashed,red,thick,
    postaction={decorate},
    decoration={
        markings,
        mark=at position 1.0 with {
            \node [blue, transform shape, anchor=base, shift={(10pt,2pt)}] 
                {Tangente en (0,0)};
        },
    },
] (0,0) coordinate(O) -- (10,8);
\draw[thick, red] (10,0) -- (10, {8(1-exp(-1))}) coordinate(T0) -- (T0-|O)node[above, anchor=east]{$\num{0.63}\cdot G\cdot U_O$};
\node[below] at (10,0){10};
\node[left] at (0,10){10};
\end{tikzpicture}%
\end{document}

score 3 · Answer 2 · answered Oct 11 '21 at 09:27

The other way to do it is to fix \pgftransformlineattime.

One should also fix \pgftransformarcaxesattime and \pgftransformcurveattime following the same idea.

\documentclass{article}
\usepackage{tikz}
\makeatletter
\def\pgftransformlineattime#1#2#3{%
  \pgfgettransformentries\aa\ab\ba\bb\notimportantx\notimportanty%%% ⬅️⬅️⬅️ new
  \pgf@process{#2}%
  \pgf@xb=\pgf@x% xb/yb = start point
  \pgf@yb=\pgf@y%
  \pgf@process{#3}%
  \pgf@xc=\pgf@x% xc/yc = end point
  \pgf@yc=\pgf@y%
  \pgftransformshift{\pgfpointlineattime{#1}{\pgfqpoint{\pgf@xb}{\pgf@yb}}{\pgfqpoint{\pgf@xc}{\pgf@yc}}}%
  \ifpgfresetnontranslationattime%
    \pgftransformresetnontranslations%
  \fi%
  \ifpgfslopedattime%
    \advance\pgf@xc by-\pgf@xb%
    \advance\pgf@yc by-\pgf@yb%
    % Now that we get the tangent vector without transformation
    % It suffices to apply the non-shift part of the transformation
    {%%% ⬇️⬇️⬇️ new
        \pgfsettransformentries\aa\ab\ba\bb{0pt}{0pt}
        \pgf@pos@transform{\pgf@xc}{\pgf@yc}
        \global\pgf@xc\pgf@xc
        \global\pgf@yc\pgf@yc
    }%%% ⬆️⬆️⬆️ new
    % OK, now xc and yc are correctly tangent to the line
    % Continue the usual routine
    \ifpgfallowupsidedownattime%
    \else%
      \ifdim\pgf@xc<0pt%
        \pgf@xc=-\pgf@xc%
        \pgf@yc=-\pgf@yc%
      \fi%
    \fi%
    \pgf@x=\pgf@xc%
    \pgf@y=\pgf@yc%
    \pgfpointnormalised{}% x/y = normalised vector
    \pgf@ya=-\pgf@y%
    \pgftransformcm%
    {\pgf@sys@tonumber{\pgf@x}}{\pgf@sys@tonumber{\pgf@y}}%
    {\pgf@sys@tonumber{\pgf@ya}}{\pgf@sys@tonumber{\pgf@x}}{\pgfpointorigin}%
  \fi%
}
\makeatother
\begin{document}
\begin{tikzpicture}[xscale=2, yscale=3, xshift=40, yshift=50]
    \draw (0, 0) -- node[sloped, above] {sloped correctly?} (2, 2);
\end{tikzpicture}%
\end{document}

You can probably submit this code to the project ;) – Kpym Oct 12 '21 at 08:05 — Kpym, Oct 12 '21 at 08:05

How to use "sloped" when the x and y scales are different?

2 Answers2

Code: