tkz arrow shows up doubled

Question

When I use the tkz arrow option to \tkzDrawArc twice, the first arrowhead gets doubled.

\documentclass{standalone}
\usepackage{tkz-euclide}
\begin{document}
\begin{tikzpicture}
   \draw (-3,-1) rectangle (3,3);
  \tkzDefPoints{0/0/O,2/0/R,-2/0/L}
  \tkzDrawArctkz arrow={stealth[scale=1.5] at .25},
  tkz arrow={stealth[scale=1.5] at .75}(L)
  \tkzDrawSegmenttkz arrow={stealth[scale=1.5] at .25},
  tkz arrow={stealth[scale=1.5] at .75}
\end{tikzpicture}

I add that the reason I am not using tkz arrows is because it doesn't appear to be configurable, and arrowheads are too big.

Personally I prefer to modify the styles outside the plots because TikZ and tkz-euclide` allow it. I find the code more readable. — Alain Matthes, Apr 19 '22 at 05:56

Alain Matthes · Accepted Answer · 2022-04-19T10:16:03.753

Arrows in tkz-euclide it is the decoration part. The main goal is the construction of geometrical figures. In this decoration part, TikZ takes a preponderant place and it is necessary to use more often the options of TikZ. The problem here is that `tkz arrows is proposed to place an arrow on each segment of a path.

So in some cases you have to go through TikZ and know a lot of its options.

The path to represent a circle is composed of four quadrants and tkz arrows allows to place 4 arrows on each quadrant here for a half circle you can expect 2 arrows.

\documentclass{standalone} 
\usepackage{tkz-euclide}
\tikzset{tkz arrows/.style= 
 {postaction={on each path={tkz arrow={Stealth[scale=1,black]}}}}}
\begin{document}
\begin{tikzpicture}
\tkzDefPoints{0/0/A, 3/0/B, -3/0/C} 
\tkzDrawSemiCircletkz arrows,thin
\end{tikzpicture}
\end{document}

I have kept scale=1 here for the following explanation. In TikZ, some objects have their size depending on the thickness of the line. You must have the same thickness here for arcs, circles etc.

I have added thin. I have to modify the tkz-euclide.cfg file because I left different thicknesses for some objects.

\documentclass{standalone} 
\usepackage{tkz-euclide}
\tikzset{tkz arrows/.style= 
 {postaction={on each path={tkz arrow={Stealth[scale=1,black]}}}}}
\begin{document}
\begin{tikzpicture}
\tkzDefPoints{0/0/A, 3/0/B, -3/0/C} 
\tkzDrawSemiCircletkz arrows,thin
\tkzDrawSegments[tkz arrows,thin](C,A A,B)
\end{tikzpicture}
\end{document}

It is also possible to place a single arrow with tkz arrow on each segment

\documentclass{standalone} 
\usepackage{tkz-euclide}
\tikzset{tkz arrows/.style= 
 {postaction={on each path={tkz arrow={Stealth[scale=1,black]}}}}}
\begin{document}
\begin{tikzpicture}
\tkzDefPoints{0/0/A, 3/0/B, -3/0/C} 
\tkzDrawSemiCircletkz arrows,thin
\tkzDrawSegments[tkz arrow={Stealth[scale=1]},thin](C,A A,B)
\end{tikzpicture}
\end{document}

Zarko · Answer 2 · 2022-04-19T07:46:18.063

4

Try the following:

\documentclass[margin=3mm]{standalone}
\usepackage{tkz-euclide}
\tikzset{tkz arrows/.style= 
    {semithick, black,
     postaction={on each path={tkz arrow={Stealth[scale=1.5,black]}}}}
        }
\begin{document}
\begin{tikzpicture}
\tkzDefPoints{0/0/A, 3/0/B, -3/0/C} 
     \tkzDrawArc[tkz arrows](A,B)(C) 
\tkzDrawSegments[tkz arrows](C,A A,B)
\end{tikzpicture}
\end{document}

edited Apr 19 '22 at 07:46

answered Apr 18 '22 at 23:55

Zarko

296,517

Yes it is a good solution – Alain Matthes Apr 19 '22 at 05:45
No need to load TikZ and its library because tkz-euclide does it – Alain Matthes Apr 19 '22 at 05:52
@AlainMatthesm thank you very much for this information. Actually I'm novice at using this attractive package. – Zarko Apr 19 '22 at 06:10
@AlainMatthes, now I see, after reading your answer (+1), that was to much follow to OP MWE and to less investigate package investigation. I wasn't aware for \tkzDrawSemiCircle. I stil wonder why the first point shouldn't be negative. I need to read documentation again and again ... – Zarko Apr 19 '22 at 07:30

score 4 · Answer 3 · answered Apr 19 '22 at 04:18

4

Just for comparison, here is a pure TikZ version.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.markings,arrows.meta}
\begin{document}
\begin{tikzpicture}
\draw[decoration={markings, mark=between positions .19 and 1 step 0.25 with {\arrow{Stealth}}}, postaction=decorate] 
    (2,0) arc (0:180:2) -- cycle;
\end{tikzpicture}
\end{document}

To make adjustments to the arrow you can use Stealth[<options>], where <options> can include length=, width=, inset=, among other things (e.g., colors). arrows.meta has many other arrow options as well.

answered Apr 19 '22 at 04:18

Sandy G

42,558

I agree that it is easy with TikZ in this case but if the half circle is not at the origin and the segment is not horizontal it might be a bit more difficult. – Alain Matthes Apr 19 '22 at 05:43
@AlainMatthes: I suppose that's true. Though you could just rotate around any point by any angle. – Sandy G Apr 19 '22 at 16:51
yes it's the method but I prefer to write DrawSemiCircle(O,A) than to go and find the necessary angles to draw an arc. However, I have to do this to write the macros of the package! – Alain Matthes Apr 19 '22 at 17:28

tkz arrow shows up doubled

3 Answers3