TikZ 中根据坐标轴进行四分之一旋转

Question

我正在尝试在 TikZ 中实现四分之一旋转样式的参数，这样

\begin{tikzpicture}
\path (2cm,1cm) coordinate (A);
\draw[blue,->]  (A) [northwestqturn=3cm];
\draw[green,->]  (A) [northeastqturn=3cm];
\draw[red,->]  (A) [southwestqturn=3cm];
\draw[yellow,->]  (A) [southeastqturn=3cm];
\draw (A) node {$\bullet$};
\end{tikzpicture}

相当于

\begin{tikzpicture}
\path (2cm,1cm) coordinate (A);
\draw[blue,->]  (A)   arc[start angle=0, delta angle=90, radius=3cm];
\draw[green,->]  (A) arc[start angle=180, delta angle=(-90), radius=3cm];
\draw[red,->]  (A) arc[start angle=0, delta angle=(-90), radius=3cm];
\draw[yellow,->]  (A)   arc[start angle=180, delta angle=90, radius=3cm];
\draw (A) node {$\bullet$};
\end{tikzpicture}

以下是我失败的尝试。我觉得这是一次险些失败的尝试，一个小拼写错误可能是导致我的代码无法运行的原因。任何帮助都非常感谢。

\documentclass{article}
\usepackage{tikz}


\tikzset{
  nwchord/.style args={#1}{
    /utils/exec=%
   radius=#1, start angle=0, delta angle=90},
  northwestqturn/.style={insert path={arc[nwchord={#1}]}},
 nwchord r/.initial=,
  nwchord do/.style={nwchord={\pgfkeysvalueof{/tikz/nwchord r}}},
}

\tikzset{
  swchord/.style args={#1}{
    /utils/exec=%
  radius=#1, start angle=270, delta angle=(-90)},
  southwestqturn/.style={insert path={arc[swchord={#1}]}},
  swchord r/.initial=,
  swchord do/.style={swchord={\pgfkeysvalueof{/tikz/swchord r}}},
}

\tikzset{
  sechord/.style args={#1}{
    /utils/exec=%
  radius=#1, start angle=180, delta angle=90},
  southeastqturn/.style={insert path={arc[sechord={#1}]}},
  sechord r/.initial=,
  sechord do/.style={sechord={\pgfkeysvalueof{/tikz/sechord r}}},
}

\tikzset{
  nechord/.style args={#1}{
    /utils/exec=%
   radius=#1, start angle=180, delta angle=(-90)},
  northeastqturn/.style={insert path={arc[nechord={#1}]}},
  nechord r/.initial=,
  nechord do/.style={nechord={\pgfkeysvalueof{/tikz/nechord r}}},
}



\begin{document}

\begin{tikzpicture}
\path (2cm,1cm) coordinate (A);
\draw[blue,->]  (A) [northwestqturn=3cm];
\draw[green,->]  (A) [northeastqturn=3cm];
\draw[red,->]  (A) [southwestqturn=3cm];
\draw[yellow,->]  (A) [southeastqturn=3cm];
\draw (A) node {$\bullet$};
\end{tikzpicture}

\begin{tikzpicture}
\path (2cm,1cm) coordinate (A);
\draw[blue,->]  (A)   arc[start angle=0, delta angle=90, radius=3cm];
\draw[green,->]  (A) arc[start angle=180, delta angle=(-90), radius=3cm];
\draw[red,->]  (A) arc[start angle=0, delta angle=(-90), radius=3cm];
\draw[yellow,->]  (A)   arc[start angle=180, delta angle=90, radius=3cm];
\draw (A) node {$\bullet$};
\end{tikzpicture}

\end{document}

Answer 1

首先，/utils/exec它的目的是通过按键来运行特定的代码，以在 TeX 中执行辅助操作。它不运行按键，不执行按键代码（除非您使用 pgfkeys 命令）。所以这里与目的无关。

/.style args是一个用于使用特定语法创建自定义键的处理程序，例如，mykey/.style args={I want an argument#1and#2with#3}您可以使用以下命令调用此键

mykey= I want an argument 3cm and green with onion

然后#1将是3cm等等。

在您的情况下，您正在定义一个样式参数，但该参数将是一个简单的参数，这意味着没有额外的模式，因此/.style就足够了。

你可以稍微简化一下

\documentclass[tikz]{standalone}
\tikzset{
  qturn/.style args ={#1with#2}{insert path={arc[#1=#2]}},
  ne/.style={radius=#1, start angle=180, delta angle=-90},
  nw/.style={radius=#1, start angle=0,   delta angle=90},
  se/.style={radius=#1, start angle=180, delta angle=90},
  sw/.style={radius=#1, start angle=0,   delta angle=(-90)},
}
\begin{document}
\begin{tikzpicture}
\path (2cm,1cm) coordinate (A);
\draw[blue,->]   (A) [qturn= ne with 3cm];
\draw[green,->]  (A) [qturn= nw with 3cm];
\draw[red,->]    (A) [qturn= se with 3cm];
\draw[yellow,->] (A) [qturn= sw with 3cm];
\draw (A) node {$\bullet$};
\end{tikzpicture}
\end{document}