如何在 Tikz 中将螺丝定义为装饰品

Question

我正在尝试定义一个装饰器，在两个连接点之间画一个螺丝。到目前为止，我所拥有的就是这样的：

\documentclass{article}   
\usepackage{tikz}
\usetikzlibrary{decorations}

\pgfdeclaredecoration{screw}{initial}
    {
    \state{initial}[width=1.5pt,next state=midd]
        {
        % First line
        \pgfpathlineto{\pgfpoint{0.0pt}{3.0pt}}
        \pgfpathlineto{\pgfpoint{1.5pt}{1.5pt}}
        % Second line
        \pgfpathmoveto{\pgfpoint{0.0pt}{0.0pt}}
        \pgfpathlineto{\pgfpoint{0.0pt}{-3.0pt}}
        \pgfpathlineto{\pgfpoint{1.5pt}{-1.5pt}}
        }
    \state{midd}[width=3.2pt]
        {
        % First line
        \pgfpathmoveto{\pgfpoint{0pt}{1.5pt}}
        \pgfpathlineto{\pgfpoint{0.6pt}{2.0pt}}
        \pgfpathlineto{\pgfpoint{1.6pt}{1.5pt}}
        \pgfpathlineto{\pgfpoint{2.6pt}{1.0pt}}
        \pgfpathlineto{\pgfpoint{3.2pt}{1.5pt}}
        % Second line
        \pgfpathmoveto{\pgfpoint{0pt}{-1.5pt}}
        \pgfpathlineto{\pgfpoint{0.6pt}{-2.0pt}}
        \pgfpathlineto{\pgfpoint{1.6pt}{-1.5pt}}
        \pgfpathlineto{\pgfpoint{2.6pt}{-1.0pt}}
        \pgfpathlineto{\pgfpoint{3.2pt}{-1.5pt}}
        }
    \state{final}
        {
        %\pgfpathlineto{\pgfpointdecoratedpathlast}
        \pgfpathmoveto{\pgfpoint{0pt}{1.5pt}}
        \pgfpathlineto{\pgfpoint{2.0pt}{0pt}}
        \pgfpathlineto{\pgfpoint{0pt}{-1.5pt}}
        }
    }
\begin{document}
\begin{tikzpicture}[scale=1]
    \draw[decorate,decoration=screw] (0,100pt) -- (0,0);
\end{tikzpicture}
\end{document}

我也想改变线的振幅和间距。我该怎么做？

Answer 1

因此，我可以用以下代码解决我的问题：

\documentclass[]{standalone}
\usepackage{tikz}
\usetikzlibrary{decorations}
% New decoration for screws
\tikzset{/pgf/decoration/.cd,
    head width/.initial=6pt,
    head length/.initial=1.5pt,
    thread separation/.initial=1.0pt,
    thread amplitude/.initial=0.5pt,
    screw radius/.initial=1.2pt,
}
% definition of the decoration
\pgfdeclaredecoration{screw}{initial}
{
  \state{initial}[width=\pgfkeysvalueof{/pgf/decoration/head length},%
                  next state=midd]
  {
    \def\headlength{%
      \pgfkeysvalueof{/pgf/decoration/head length}%
    }
    \def\headwidth{%
      \pgfkeysvalueof{/pgf/decoration/head width}%
    }
    \def\screwradius{%
      \pgfkeysvalueof{/pgf/decoration/screw radius}%
    }
    % First line
    \pgfpathlineto{\pgfpoint{0.0pt}{\headwidth/2}}
    \pgfpathlineto{\pgfpoint{\headlength}{\screwradius}}
    % Second line
    \pgfpathmoveto{\pgfpoint{0.0pt}{0.0pt}}
    \pgfpathlineto{\pgfpoint{0.0pt}{-\headwidth/2}}
    \pgfpathlineto{\pgfpoint{\headlength}{-\screwradius}}
  }
  \state{midd}[width=\pgfkeysvalueof{/pgf/decoration/thread separation}*2]
  {
    \def\threadseparation{%
      \pgfkeysvalueof{/pgf/decoration/thread separation}%
    }
    \def\threadamplitude{%
      \pgfkeysvalueof{/pgf/decoration/thread amplitude}%
    }
    \def\screwradius{%
      \pgfkeysvalueof{/pgf/decoration/screw radius}%
    }
    % First line
    \pgfpathmoveto{\pgfpoint{0pt}{\screwradius}}
    \pgfpathlineto{\pgfpoint{0.5*\threadseparation}{\screwradius+\threadamplitude}}
    \pgfpathlineto{\pgfpoint{1.0*\threadseparation}{\screwradius}}
    \pgfpathlineto{\pgfpoint{1.5*\threadseparation}{\screwradius-\threadamplitude}}
    \pgfpathlineto{\pgfpoint{2.0*\threadseparation}{\screwradius}}
    % Second line
    \pgfpathmoveto{\pgfpoint{0pt}{-\screwradius}}
    \pgfpathlineto{\pgfpoint{0.5*\threadseparation}{-\screwradius-\threadamplitude}}
    \pgfpathlineto{\pgfpoint{1.0*\threadseparation}{-\screwradius}}
    \pgfpathlineto{\pgfpoint{1.5*\threadseparation}{-\screwradius+\threadamplitude}}
    \pgfpathlineto{\pgfpoint{2.0*\threadseparation}{-\screwradius}}
    % Thread
    \pgfpathmoveto{\pgfpoint{0.5*\threadseparation}{\screwradius+\threadamplitude}}
    \pgfpathlineto{\pgfpoint{1.5*\threadseparation}{-\screwradius+\threadamplitude}}
  }
  \state{final}
  {
    \def\screwradius{%
      \pgfkeysvalueof{/pgf/decoration/screw radius}%
    }
    %\pgfpathlineto{\pgfpointdecoratedpathlast}
    \pgfpathmoveto{\pgfpoint{0pt}{\screwradius}}
    \pgfpathlineto{\pgfpoint{2.0pt}{0pt}}
    \pgfpathlineto{\pgfpoint{0pt}{-\screwradius}}
  }
}
\begin{document}
\begin{tikzpicture}[scale=1]
  \node (a) at (0pt,50pt) {};
  \node (b) at (0pt,0pt) {};
  \draw[decorate, decoration={screw}] (a) -- (b);
\end{tikzpicture}

\begin{tikzpicture}[scale=1]
  \node (c) at (0pt,50pt) {};
  \draw[decorate, decoration={screw, thread separation=0.5pt}] (c) arc(-180:-90:40pt);
\end{tikzpicture}

\begin{tikzpicture}[scale=1]
  \node (d) at (0pt,0pt) {};
  \node (e) at (70pt,0pt) {};
  \draw[decorate, decoration={screw, screw radius=5pt, head width=15pt, head length=3pt}] (a) -- (b);
\end{tikzpicture}

\end{document}