使用 tikz 添加非直线路径

Question

此代码

\begin{tikzpicture}
  % Vertice con 5 archi
  \node[circle, draw] (v) at (0,0) {V};
  
  % Archi tratteggiati
  \draw (v.45) -- ++(45:1);
  \draw (v.90) -- ++(90:1);
  \draw (v.135) -- ++(135:1);
  \draw (v.180) -- ++(180:1);
  \draw (v.225) -- ++(225:1);
  \draw[dashed] (v.45) -- ++(45:2);
  \draw[dashed] (v.90) -- ++(90:2);
  \draw[dashed] (v.135) -- ++(135:2);
  \draw[dashed] (v.180) -- ++(180:2);
  \draw[dashed] (v.225) -- ++(225:2);
\end{tikzpicture}

绘制下面的图片

我想添加一条非直线路径，使用不同的颜色，从一条线进入并从另一条线退出，类似于下图所示的路径（由我手动修改）：

我怎样才能获得这个结果？

Answer 1

耐心地使用 Luc Cholet 的Geogebra文件https://www.geogebra.org/m/RwNHMPk9，我们可以创建贝塞尔曲线。

• 为了更容易在 Geogebra 中定位点 p1 和 p2，我们将minimum width=1cm包含 V 的节点设置为
• 在 Geogebra 中，我们通过在输入字段中输入来重新定义点 A 的坐标A=(2.5; 45°)

• 我们可以使用 + 按钮一次添加一个控制点。

• 最后使用 tikz 按钮复制然后粘贴到 tex 文件中

代码

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
  % Vertice con 5 archi
  \node[circle, draw,minimum width=1cm] (v) at (0,0) {V};%<-- modif
  % Archi tratteggiati
  \draw (v.45) -- ++(45:1);
  \draw (v.90) -- ++(90:1);
  \draw (v.135) -- ++(135:1);
  \draw (v.180) -- ++(180:1);
  \draw (v.225) -- ++(225:1);
  \draw[dashed] (v.45) -- ++(45:2)coordinate(p1);
  \draw[dashed] (v.90) -- ++(90:2)coordinate(p2);
  \draw[dashed] (v.135) -- ++(135:2);
  \draw[dashed] (v.180) -- ++(180:2);
  \draw[dashed] (v.225) -- ++(225:2);
  %
  \draw [green](p1)%<-- mdif after copy
  % \draw (1.7677669529663689,1.7677669529663687) 
  .. controls (3.1070703811315195,3.165645932288138 ) and (1.7281913375772981,2.434840039204401 ) .. (1.5696202475685628,2.2693745539778947)
  .. controls (1.4110491575598274,2.1039090687513884 ) and (1.2111116962444652,2.579622338777594 ) .. (1.5075706906086228,2.620988710084221)
  .. controls (1.8040296849727804,2.6623550813908476 ) and (1.245583672333321,3.1242795609815115 ) .. (0.9767022588402476,2.5865167339953654)
  .. controls (0.7078208453471744,2.0487539070092193 ) and (0.5,3.5 ) .. 
  % (0,2.5);
  (p2);%<-- mdif after copy
\end{tikzpicture}
\end{document}

Answer 2

整合几个库……

• arrows.meta以及bending可定制且灵活/可弯曲的箭头，
• decorations.markings用于沿路径放置箭头，
• ext.arrows从我的tikz-ext包裹对于Centered Straight Barb箭头，
• fpu更多精确的veclen函数会修复Dimension too large一些贝塞尔曲线的错误，
• hobbysmooth寻找通过坐标构造曲线的 plothandler的替代方案，以及
• math允许简单的界面进行即时计算。

后者用于不是使用随机坐标但虚线的终点。

两者hobby和smooth绘图处理器允许定制底层算法来通过给定的点构建曲线。

默认输出如下所示。

代码

\documentclass[tikz]{standalone}
\usetikzlibrary{
  arrows.meta,          % customizable arrow tips
  bending,              % flexed and bended arrow tips
  decorations.markings, % place arrow tips along any path
  ext.arrows,           % Centered Straight Barb
  fpu,                  % more precise veclen function for decoration along curve
  hobby,                % nicer (?) curves through points
  math}                 % on-the-fly calculations
\begin{document}
\begin{tikzpicture}[
  thick, arrows={[round, scale=.5]},
  >      ={         Straight Barb[flex']}, % arrow tip for the end
  >'/.tip={Centered Straight Barb[quick]}] % arrow tip for along the path
\pgfmathsetseed{699943}
\node[circle, draw] (v) at (0,0) {V};
\foreach[count=\i from 0] \ang in {45, 90, ..., 225}
  \path (v.\ang) edge coordinate[at end](v'\i)  (\ang:1)
        (v'\i)   edge[dash pattern=on 1.3333mm off 1mm]
                      coordinate[at end](v''\i) (\ang:2);
\draw[
  cyan, <-, thin, /pgf/fpu/install only=veclen,
  postaction=decorate,
  decoration={
    name=markings,
    mark=between positions .125 and .875 step .125 with \arrowreversed{>'}
  }
] plot[smooth, samples at={0, ..., 40}]
  ([evaluate={
      coordinate \p; int \i;
      if mod(\x,10) == 0 then {
        \i = int(\x/10);
        \p = (v''\i);
      } else {
        \p = ({45+\x/40*180+rand}:{2+rand*.2});
      };}, shift={(\p)}]0pt,0pt);
\end{tikzpicture}
\begin{tikzpicture}[
  thick, arrows={[round, scale=.5]},
  >      ={         Straight Barb[flex']}, % arrow tip for the end
  >'/.tip={Centered Straight Barb[quick]}] % arrow tip for along the path
\pgfmathsetseed{699943}
\node[circle, draw] (v) at (0,0) {V};
\foreach[count=\i from 0] \ang in {45, 90, ..., 225}
  \path (v.\ang) edge coordinate[at end](v'\i)  (\ang:1)
        (v'\i)   edge[dash pattern=on 1.3333mm off 1mm]
                      coordinate[at end](v''\i) (\ang:2);
\draw[
  cyan, <-, thin, /pgf/fpu/install only=veclen,
  postaction=decorate,
  decoration={
    name=markings,
    mark=between positions .125 and .875 step .125 with \arrowreversed{>'}
  }
] plot[hobby, samples at={0, ..., 40}]
  ([evaluate={
      coordinate \p; int \i;
      if mod(\x,10) == 0 then {
        \i = int(\x/10);
        \p = (v''\i);
      } else {
        \p = ({45+\x/40*180+rand}:{2+rand*.2});
      };}, shift={(\p)}]0pt,0pt);
\end{tikzpicture}
\end{document}

输出