如何填入pgf/tikz中3條弧的重疊部分？

Question

我有一張圖片如下：

\documentclass{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
  \draw(0,0) -- (4,0) -- (4,4) -- (0,4) -- (0,0);
  \draw(0,0) arc(-90:90:2);
  \draw[dashed](0,0) arc(-90:-270:2);  
  \draw(0,0) arc(180:90:4);
  \draw(0,0) arc(180:90:4);
  \draw[dashed](0,0) arc(-180:90:4);  
  \draw(4,0) arc(-90:-180:4);
  \draw[dashed](4,0) arc(-90:180:4);  
\end{tikzpicture}

\end{document}

現在我要在3個圓弧重疊的部分上繪製陰影，我該怎麼做？就像這張圖一樣：

如果我想在ABC之間畫線，該怎麼辦？太感謝了！

Answer 1

除了填滿線的陰影之外，還有類似這樣的東西。您可以在環境\clip內部的一些幫助下完成此操作scope。若要設定交叉點的座標，請使用該intersections庫。

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{patterns,intersections}
\begin{document}

\begin{tikzpicture}
  \begin{scope}
    \clip(0,2) circle (2);
    \clip(4,0) circle (4);
    \fill[pattern=north west lines,pattern color=red](4,4) circle (4);
  \end{scope}
  %\draw(0,0) -- (4,0) -- (4,4) -- (0,4) -- (0,0);
  \draw (0,0) rectangle (4,4);
  \draw[name path=left](0,0) arc(-90:90:2);
  \draw[dashed](0,0) arc(-90:-270:2);  
  \draw[name path=lower](0,0) arc(180:90:4);
  %\draw(0,0) arc(180:90:4);
  \draw[dashed](0,0) arc(-180:90:4);  
  \draw[name path=upper](4,0) arc(-90:-180:4);
  \draw[dashed](4,0) arc(-90:180:4);  
  %%
  \path [name intersections={of=lower and upper}];
  \coordinate (A) at (intersection-1);
  \path [name intersections={of=left and upper}];
  \coordinate (B) at (intersection-1);
  \path [name intersections={of=left and lower}];
  \coordinate (C) at (intersection-2);
  %%
  \node[left,red] at (A) {A};
  \node[below,red] at (B) {B};
  \node[above,red] at (C) {C};
  %%
  \fill[blue,fill=blue,opacity=0.3] (A)--(B)--(C)--cycle;
  \draw[blue,thick] (A)--(B)--(C)--cycle;
\end{tikzpicture}

\end{document}