填充两条曲线之间的区域

Question

[reverse]您只需要在其中一个段中添加即可。

\documentclass[margin=10pt]{standalone}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usepgfplotslibrary{fillbetween}
\usetikzlibrary{intersections}


\begin{document}
\begin{tikzpicture}%[x=1cm, y=1cm]
\def\rsmall{2}
\def\rlarge{4}
\def\alpha{60}
\def\beta{40}
\def\gamma{20}
\def\Aout{\alpha+\gamma-90}
\def\Bin{270-\beta-\gamma}

\pgfmathsetmacro\ax{-\rsmall+cos(\alpha)*\rsmall}
\pgfmathsetmacro\ay{sin(\alpha)*\rsmall}
\pgfmathsetmacro\bx{\rlarge-cos(\beta)*\rlarge}
\pgfmathsetmacro\by{sin(\beta)*\rlarge}

\filldraw[name path=arcs, fill=gray!20, thick]
    (180:2*\rsmall) arc (180:0:\rsmall) arc (180:0:\rlarge);

\coordinate (A) at (\ax, \ay);
\coordinate (B) at (\bx, \by);

\draw[name path=unduloid, thick] (A) to[out=\Aout, in=\Bin] (B);


\path[%draw=red,thick,
fill=blue!20,intersection segments={of=unduloid and arcs,sequence={L2--R2[reverse]}}];


\end{tikzpicture}
\end{document}

如何调试？只需在相关线段上画带箭头的曲线即可。这里可以添加

\draw[red,thick,-latex,
intersection segments={of=unduloid and arcs,sequence={L2}}];

\draw[blue,thick,-latex,
intersection segments={of=unduloid and arcs,sequence={R2}}];

然后得到

这意味着路径的起点和终点都相同。要解决这个问题，即产生一个循环，你必须沿着该reverse方向穿过其中一条路径。如果你不这样做，Ti钾Z 会自行用直线闭合路径。这就是为什么你会得到一条边界曲线的直线。

附录：在这种情况下，您实际上并不需要所有段或fillbetween库。我个人也不建议重新定义等\alpha，\beta因为您可能需要这些希腊符号。

\documentclass[margin=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}


\begin{document}
\begin{tikzpicture}%[x=1cm, y=1cm]
\def\rsmall{2}
\def\rlarge{4}
\def\myalpha{60}
\def\mybeta{40}
\def\gamma{20}
\def\Aout{\myalpha+\gamma-90}
\def\Bin{270-\mybeta-\gamma}


\filldraw[fill=gray!20, thick]
    (180:2*\rsmall) arc (180:0:\rsmall) arc (180:0:\rlarge);

\coordinate (A) at ($(-\rsmall,0)+(\myalpha:\rsmall)$);
\coordinate (B) at ($(\rlarge,0)+(180-\mybeta:\rlarge)$);

\draw[red,fill=blue!20, thick] (A) to[out=\Aout, in=\Bin] (B)
arc(180-\mybeta:180:\rlarge) arc(0:\myalpha:\rsmall) -- cycle;

\end{tikzpicture}
\end{document}

Answer 1