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用什么来拉绳子的？

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用什么来拉绳子的？

我偶然发现了以下这个，画了一条连接两点的绳子。这是定制物品，还是从包裹里拿出来的？

如果是定制的，那么构建这样的东西的最佳方法是什么，而又不让代码过于复杂？

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答案1

按照这些线条画一些东西并不太难。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{decorations.markings}
\begin{document}
  \begin{tikzpicture}
    \draw[decorate,decoration={markings,
    mark=between positions 2mm and \pgfdecoratedpathlength-2mm step 2mm
      with
      {
        \draw[ultra thick,gray] 
        (-3.5mm,-1.25mm) to[out=0,in=160] (-2mm,-1.25mm) to[out=-20,in=160] 
        (2mm,1.25mm) to[out=-20,in=180] (3.5mm,1.25mm);
      }}] 
    (0,0) -- (4,-4);
    \fill (0,0) circle (3mm);   
  \end{tikzpicture}
\end{document}

在此处输入图片描述

一种可以说更清洁的方法是使用装饰来实现。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{decorations} %  decorations.text just 4 fun

\pgfkeys{/tikz/.cd,
    rope width/.store in=\RopeWidth,
    rope width=5pt,
    rope step/.store in=\RopeStep,
    rope step=2mm,
}

\pgfdeclaredecoration{rope}{initial}
{% 
\state{initial}[width=\RopeStep,next state=cont] {
    \pgfmoveto{\pgfpoint{0pt}{-\RopeWidth/2}}
    \pgfpathcurveto
    {\pgfpoint{5*\RopeStep/6}{0.25*\RopeWidth}}
    {\pgfpoint{7*\RopeStep/6}{0.45*\RopeWidth}}
    {\pgfpoint{1.5*\RopeStep}{\RopeWidth/2}}
     \pgfpathcurveto
    {\pgfpoint{10*\RopeStep/6}{0.55*\RopeWidth}}
    {\pgfpoint{11*\RopeStep/6}{0.6*\RopeWidth}}
    {\pgfpoint{13.5*\RopeStep/6}{\RopeWidth/2}}
    \pgfcoordinate{lastup}{\pgfpoint{-1.5*\RopeStep/6}{-\RopeWidth/2}}
  }
  \state{cont}[width=\RopeStep]{ 
     \pgfmoveto{\pgfpointanchor{lastup}{center}}
     \pgfpathcurveto
    {\pgfpoint{-5*\RopeStep/6}{-0.6*\RopeWidth}}
    {\pgfpoint{-4*\RopeStep/6}{-0.55*\RopeWidth}}
    {\pgfpoint{-3*\RopeStep/6}{-0.55*\RopeWidth}}
     \pgfpathcurveto
    {\pgfpoint{-\RopeStep/6}{-0.45*\RopeWidth}}
    {\pgfpoint{\RopeStep/6}{-0.25*\RopeWidth}}
    {\pgfpoint{3*\RopeStep/6}{0pt}}
    \pgfpathcurveto
    {\pgfpoint{5*\RopeStep/6}{0.25*\RopeWidth}}
    {\pgfpoint{7*\RopeStep/6}{0.45*\RopeWidth}}
    {\pgfpoint{9*\RopeStep/6}{\RopeWidth/2}}
     \pgfpathcurveto
    {\pgfpoint{10*\RopeStep/6}{0.55*\RopeWidth}}
    {\pgfpoint{11*\RopeStep/6}{0.6*\RopeWidth}}
    {\pgfpoint{13.5*\RopeStep/6}{\RopeWidth/2}}
    \pgfcoordinate{lastup}{\pgfpoint{-1.5*\RopeStep/6}{-\RopeWidth/2}}
  }
  \state{final}[width=5pt]
  {
     \pgfmoveto{\pgfpointanchor{lastup}{center}}
     \pgfpathcurveto
    {\pgfpoint{-5*\RopeStep/6}{-0.6*\RopeWidth}}
    {\pgfpoint{-4*\RopeStep/6}{-0.55*\RopeWidth}}
    {\pgfpoint{-0.5*\RopeStep}{-0.55*\RopeWidth}}
     \pgfpathcurveto
    {\pgfpoint{-\RopeStep/6}{-0.45*\RopeWidth}}
    {\pgfpoint{\RopeStep/6}{-0.25*\RopeWidth}}
    {\pgfpoint{0.5*\RopeStep}{0pt}}
    \pgfmoveto{\pgfpointdecoratedpathlast}
  }
}
\begin{document}
\begin{tikzpicture}[decoration=rope]
  \draw[red,thick,decorate,rope width=8pt] (-4,0) to[out=0,in=90] (0,-4);
  \draw[gray,thick,decorate] (0,0) to (4,-4);
  \draw[blue,ultra thick,decorate,rope width=8pt] (4,0) to (8,-4);
  \fill (-4,0) circle (8pt) (0,0) circle (8pt) (4,0) circle (8pt);
\end{tikzpicture}  
\end{document}

在此处输入图片描述

这些装饰都有待改进，特别是沿着弯曲路径的装饰有一些小的缝隙。

附录：这是没有缝隙的版本。但是曲率大的时候看起来不太好看。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{decorations} %  decorations.text just 4 fun
\newcounter{ropept}
\pgfkeys{/tikz/.cd,
    rope width/.store in=\RopeWidth,
    rope width=5pt,
    rope step/.store in=\RopeStep,
    rope step=2mm,
}

\pgfdeclaredecoration{rope}{initial}
{% 
\state{initial}[width=\RopeStep,next state=cont] {
    \pgfmoveto{\pgfpoint{0pt}{-\RopeWidth/2}}
    \pgfpathcurveto
    {\pgfpoint{5*\RopeStep/6}{0.25*\RopeWidth}}
    {\pgfpoint{7*\RopeStep/6}{0.45*\RopeWidth}}
    {\pgfpoint{1.5*\RopeStep}{\RopeWidth/2}}
     \pgfpathcurveto
    {\pgfpoint{10*\RopeStep/6}{0.55*\RopeWidth}}
    {\pgfpoint{11*\RopeStep/6}{0.6*\RopeWidth}}
    {\pgfpoint{13.5*\RopeStep/6}{\RopeWidth/2}}
    \setcounter{ropept}{0}
    \pgfcoordinate{lastup-\theropept}{\pgfpoint{-1.5*\RopeStep/6}{-\RopeWidth/2}}
    \pgfcoordinate{rope-auxA-\theropept}{\pgfpoint{13.5*\RopeStep/6}{\RopeWidth/2}}
  }
  \state{cont}[width=\RopeStep]{ 
     \pgfmoveto{\pgfpointanchor{lastup-\theropept}{center}}
     \pgfpathcurveto
    {\pgfpoint{-5*\RopeStep/6}{-0.6*\RopeWidth}}
    {\pgfpoint{-4*\RopeStep/6}{-0.55*\RopeWidth}}
    {\pgfpoint{-3*\RopeStep/6}{-0.55*\RopeWidth}}
     \pgfpathcurveto
    {\pgfpoint{-\RopeStep/6}{-0.45*\RopeWidth}}
    {\pgfpoint{\RopeStep/6}{-0.25*\RopeWidth}}
    {\pgfpoint{3*\RopeStep/6}{0pt}}
    \pgfpathcurveto
    {\pgfpoint{5*\RopeStep/6}{0.25*\RopeWidth}}
    {\pgfpoint{7*\RopeStep/6}{0.45*\RopeWidth}}
    {\pgfpoint{9*\RopeStep/6}{\RopeWidth/2}}
     \pgfpathcurveto
    {\pgfpoint{10*\RopeStep/6}{0.55*\RopeWidth}}
    {\pgfpoint{11*\RopeStep/6}{0.6*\RopeWidth}}
    {\pgfpoint{13.5*\RopeStep/6}{\RopeWidth/2}}
    \pgfmoveto{\pgfpointanchor{rope-auxA-\theropept}{center}}
    \pgfpathlineto{\pgfpoint{9*\RopeStep/6}{\RopeWidth/2}}
    \stepcounter{ropept}
    \pgfcoordinate{lastup-\theropept}{\pgfpoint{-1.5*\RopeStep/6}{-\RopeWidth/2}}
    \pgfcoordinate{rope-auxA-\theropept}{\pgfpoint{13.5*\RopeStep/6}{\RopeWidth/2}}
  }
  \state{final}[width=5pt]
  {
     \pgfmoveto{\pgfpointanchor{lastup-\theropept}{center}}
     \pgfpathcurveto
    {\pgfpoint{-5*\RopeStep/6}{-0.6*\RopeWidth}}
    {\pgfpoint{-4*\RopeStep/6}{-0.55*\RopeWidth}}
    {\pgfpoint{-0.5*\RopeStep}{-0.55*\RopeWidth}}
     \pgfpathcurveto
    {\pgfpoint{-\RopeStep/6}{-0.45*\RopeWidth}}
    {\pgfpoint{\RopeStep/6}{-0.25*\RopeWidth}}
    {\pgfpoint{0.5*\RopeStep}{0pt}}
    \pgfmoveto{\pgfpointdecoratedpathlast}
    \xdef\LastRope{\theropept}
  }
}
\begin{document}
\begin{tikzpicture}[decoration=rope]
  \draw[decorate] plot[smooth cycle, fill=yellow, thick] coordinates{ (4.,8.4) (6.5,9.) (8.,9) (9.,8.1) (11.34,6.18) (11,4) (11.3,2.2) (10.2 7,0.7 ) (8. 4,0.14) (6.2,0.29) (4.40,0.51) (3.2,0.29) (1.5,0.34) } ; 
  \typeout{\theropept}
\end{tikzpicture}  
\end{document}

在此处输入图片描述

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