从椭圆表面辐射出的箭头

Question

我想画出从椭圆表面发出的箭头。这是我得到的（箭头没有接触表面）：

\documentclass[border={2pt 2pt 2pt 2pt}]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows,positioning} 
\usetikzlibrary{shapes.geometric}
\usetikzlibrary{fadings,shadings}
\begin{document}
\begin{tikzpicture}[fill=red!20]
\draw (0,0) ellipse (2cm and 1cm);
\foreach \i in {0,45,...,315}
{
\begin{scope}[rotate=\i] 
\draw[-latex,thick] (2.1,0) -- (3,0);
\end{scope}
}
\end{tikzpicture}

\结束{文档}

Answer 1

我通过自定义椭圆节点来解决这个问题：

\documentclass[border={2pt 2pt 2pt 2pt}]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\tikzset{
  myellipse/.style args={#1 and #2}{
    shape=ellipse,
    minimum width=#1,
    minimum height=#2,
  }
}

\begin{document}
\begin{tikzpicture}
  \node[myellipse=2cm and 1cm, draw] (a) at (0,0) {};
  \foreach \i in {0, 45, ..., 315} {
    \draw[->] (a.\i) -- +(\i:.5cm);
  }
\end{tikzpicture}
\end{document}