范围内的剪辑在背景上有所不同

Question

目前，我想在圆圈内添加背景图像。为了简单起见，我在 MWE 中使用颜色。当我在背景上使用裁剪功能时，它们的工作方式与我预期的不同。

如何才能在背景上达到预期的效果？

这是我的 MWE：

\documentclass[border=1pt, tikz]{standalone}
\usetikzlibrary{positioning}
\usetikzlibrary{backgrounds}

\begin{document}
\begin{tikzpicture}[
    every circle/.style = {draw, radius=40mm}
    , every node/.style = {rectangle, rounded corners, fill=white}
    ]
        
    \coordinate (zero) at (0, 0);
    \node at (zero) {A};

    \draw (zero) ++(90:30mm) coordinate (circ1) circle ++(90:10mm) node {B};
    \draw (zero) ++(270:30mm) coordinate (circ2) circle ++(270:10mm) node {C};
        
    \begin{scope}[on background layer]
        \path[clip] (circ1) circle;
        \node[fill=blue, minimum size=100mm] at (circ1) {};
    \end{scope}
    \begin{scope}[on background layer]
        \path[clip] (circ2) circle;
        \node[fill=red, minimum size=100mm] at (circ2) {};
    \end{scope}
\end{tikzpicture}
\end{document}

预期（删除“在背景层上”）：

结果：

Answer 1

您添加的命令on background layer将被累积起来并放在一张图片中。这意味着您需要额外的作用域环境：

\documentclass[border=1pt, tikz]{standalone}

\usetikzlibrary{positioning}
\usetikzlibrary{backgrounds}

\begin{document}
\begin{tikzpicture}[
    every circle/.style = {draw, radius=40mm}
    , every node/.style = {rectangle, rounded corners, fill=white}
    ]

    \coordinate (zero) at (0, 0);
    \node at (zero) {A};

    \draw (zero) ++(90:30mm) coordinate (circ1) circle ++(90:10mm) node {B};
    \draw (zero) ++(270:30mm) coordinate (circ2) circle ++(270:10mm) node {C};

    \begin{scope}[on background layer]
      \begin{scope}
        \path[clip] (circ1) circle;
        \node[fill=blue, minimum size=100mm] at (circ1) {};
      \end{scope}        
    \end{scope}
    \begin{scope}[on background layer]
      \begin{scope}
        \path[clip] (circ2) circle;
        \node[fill=red, minimum size=100mm] at (circ2) {};
      \end{scope}        
    \end{scope}
\end{tikzpicture}
\end{document}