How to make those lines in Tikz?

Question

Here the lines:

I have no idea how to make the little bump. If only it were straight lines :)

Colors are:

• green: #9DC634
• orange: #F39614
• pink: #F39614
• purple: #AB7CB5

Thanks for your help

Answer 1

Update: I' adding a second way to do it.

1. The first way uses double line and clips.
2. The second way uses arcs. Easier this way but not valid for any kind of curve.

\documentclass[tikz,border=2mm]{standalone}
\newcommand{\myline}{(0,0) -- (5,0) to[out=0,in=180] (6,0.25) to[out=0,in=180] (7,0) -- (8,0)}
\definecolor{mygreen} {HTML}{9DC634}
\definecolor{myorange}{HTML}{F39614}
\definecolor{mypink}  {HTML}{FF00FF} % changed
\definecolor{mypurple}{HTML}{AB7CB5}
\begin{document}
\begin{tikzpicture}
\useasboundingbox (-0.5,-1.5) rectangle (8.5,1);
% first way
\begin{scope}
\clip (0,-1) rectangle (8,1);
\begin{scope}
\clip\myline |- (0,1) --cycle;
\draw[mypurple,double distance=1.5mm-\pgflinewidth] \myline;
\draw[mypink  ,double distance=0.5mm-\pgflinewidth] \myline;
\end{scope}
\begin{scope}
\clip\myline |- (0,-1) --cycle;
\draw[mygreen ,double distance=1.5mm-\pgflinewidth] \myline;
\draw[myorange,double distance=0.5mm-\pgflinewidth] \myline;
\end{scope}
\end{scope}
% second way
\begin{scope}[shift={(0,-1)}]
\foreach[count=\ii]\i in {mygreen,myorange,mypink,mypurple}
  \draw[draw=\i] (0,0.05\ii) --++ (1,0) arc (270:290:1.5-0.05\ii) arc (110:70:2+0.05\ii)
                                         arc (250:270:1.5-0.05\ii) --  (8,0.05*\ii);
\end{scope}
\end{tikzpicture}
\end{document}

Answer 2

Making Bézier curves parallel isn't a trivial problem. Here's a third hacky approach.

Code

\documentclass[tikz]{standalone}
\begin{document}
\tikz[
  very thick,
  loo/.style args={#1:#2}{#1 looseness=1.05^\i,#2 looseness=.95^\i}
] \foreach[count=\i]\c in {9DC634, F39614, FFC0CB, AB7CB5}
    \color[HTML]{\c}
    \draw[yshift=\i mm, out=0, in=180] (0,0) --++(right:3)
      to[loo=in:out] ++(2,.5) to[loo=out:in] ++(2,-.5) -- ++(right:1);
\end{document}

Output

Answer 3

You could bend the line a bit:

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[rounded corners=0.2cm]
\draw[red] (0,0) -- (5,0) to[bend left=35] (7,0) -- (9,0);
\draw[green,yshift=1mm] (0,0) -- (5,0) to[bend left=35] (7,0) -- (9,0);
\end{tikzpicture}
\end{document}

Answer 4

Just for fun, here're two new approaches both try to avoid parsing the same path multiple times, and both need to manually enlarging bounding boxes.

• one uses save path=<macro> and use path=<macro>
• the other uses postaction={<options>}

\documentclass[tikz,border=2mm]{standalone}
% taken from Juan Castaño's answer https://tex.stackexchange.com/a/679439
\newcommand{\myline}{(0,0) -- (5,0) to[out=0,in=180] (6,0.25) to[out=0,in=180] (7,0) -- (8,0)}
\definecolor{mygreen} {HTML}{9DC634}
\definecolor{myorange}{HTML}{F39614}
\definecolor{mypink}  {HTML}{FF00FF} % changed
\definecolor{mypurple}{HTML}{AB7CB5}
\begin{document}
% using \foreach with option count
% similar to Qrrbrbirlbel's answer https://tex.stackexchange.com/a/679440
\begin{tikzpicture}
  \foreach \i[count=\n] in {mygreen, myorange, mypink, mypurple} {
    \draw[\i, yshift=3pt*\n] \myline;
  }
\end{tikzpicture}
% using save path and use path to accelerate path parsing
% manual bounding box enlarging needed
\begin{tikzpicture}
  \path[save path=\mypath] \myline;
  \foreach \i[count=\n from 0] in {mygreen, myorange, mypink, mypurple} {
    \draw[\i, transform canvas={yshift=3pt*\n}, use path=\mypath];
  }
  \path (0,.5);
\end{tikzpicture}
% using postaction with transform canvas
% manual bounding box enlarging needed
\begin{tikzpicture}
  \draw[
    mygreen,
    postaction={draw=myorange, transform canvas={yshift=3pt}},
    postaction={draw=mypink,   transform canvas={yshift=6pt}},
    postaction={draw=mypurple, transform canvas={yshift=9pt}}
  ]
    (0,0) -- (5,0) to[out=0,in=180] (6,0.25) to[out=0,in=180] (7,0) -- (8,0);
  \path (0,.5);
\end{tikzpicture}
\end{document}

Answer 5

Here is another solution using tikz-nfold, credits to this answer for the colors.

The advantages of this solution include that it works with almost every path, and that the curved parts are all at a constant distance from each other. Disadvantages are that you have to load another library, and that the compile times can be a bit longer.

Update

The interface has gotten simpler with tikz-nfold version 0.1.0:

\usepackage{tikz}
\usetikzlibrary{nfold}
[...]
\begin{tikzpicture}
  \path[save path=\mypath]
    (0,0) -- (5,0) to[out=0, in=180] (7,.75) to[out=0, in=180] (9,0) -- (10,0);
  \pgfsetlinewidth{1pt}
  \foreach \mycolor [count=\i] in {9DC634,F39614,FF00FF,AB7CB5}
    \definecolor{tempcolor}{HTML}{\mycolor}
    \color{tempcolor}
    \pgfoffsetpathindex{\mypath}{8pt}{\i}{4}
    \pgfusepathqstroke;
\end{tikzpicture}

Answer 6

An interesting approach taken from this nice answer:

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
  \color[HTML]{9DC634}
  \draw (0,0) -- (1,0) coordinate (A) 
    .. controls +(1,0) and +(-1,0) .. (3,1) coordinate (B) 
    .. controls +(1,0) and +(-1,0) .. (5,0) coordinate (C) -- (6,0);
\path (A) .. controls +(1,0) and +(-1,0) .. (B) 
    { \foreach \i in {1,...,40} { coordinate[pos={\i/40}] (p\i) } };
  \path (B) .. controls +(1,0) and +(-1,0) .. (C) 
    { \foreach \i in {40,...,80} { coordinate[pos={(\i-40)/40}] (p\i) } };
\foreach \d/\c in {1mm/F39614, 2mm/FFC0CB, 3mm/AB7CB5} {
    \color[HTML]{\c}
    \draw (0,\d) -- ($(p1)!\d!90:(p2)$) 
       { \foreach \i [count=\j from 3] in {2,...,79} {-- ($(p\i)!\d!90:(p\j)$) } }
       -- ($(p80)!\d!-90:(p79)$) -- (6,\d);
  }
  \end{tikzpicture}
\end{document}