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有没有办法在制作 tikz pgf 图时控制不同元素的渲染顺序？

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有没有办法在制作 tikz pgf 图时控制不同元素的渲染顺序？

我正在为学生制作几份讲义，我注意到图表元素的显示顺序可能会分散注意力。这是一张放大的图片，你可以看到我的意思。x=-2 处的圆应该是图表中的一个洞，但它出现在线的下面。y=0 处的线和网格本身也是如此。似乎元素的呈现顺序与我需要的顺序完全相反。 重叠 有没有办法控制顺序，让网格位于所有内容之下，y=0 位于轴上方（因此中间没有黑线），并且两个圆圈位于所有内容之上？此图的代码如下：

\documentclass[12pt]{extarticle}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}

\pgfplotsset{vasymptote/.style={
    before end axis/.append code={
        \draw[densely dashed, magenta] ({rel axis cs:0,0} -| {axis cs:#1,0})
        -- ({rel axis cs:0,1} -| {axis cs:#1,0});
    }
}}

\begin{document}
    \begin{tikzpicture}
      \def\FunctionF(#1){(#1+2)/((#1)^2-4)}
      \def\FunctionG(#1){0}
      \begin{axis}[
        axis y line=center,
        axis x line=middle, 
        axis on top=false,
        xmin=-6.5, xmax=6.5,
        ymin=-6.5, ymax=6.5,
        grid,
        xtick={-6,...,6},
        ytick={-6,...,6},
        yticklabels={-6,,-4,,-2,,,,2,,4,,6},
        xticklabels={-6,,-4,,-2,,,,2,,4,,6},
        vasymptote=2,
        ]

        % Hole
        \coordinate (A) at (-2,-1/4);   
        % y-intercept        
        \coordinate (B) at (0,-1/2);

        % Hole 
        \draw[magenta, thick, fill=white] (A) circle (2pt);
        % y-intercept        
        \filldraw[magenta, thick] (B) circle (2pt);

        % f(x)
        \addplot [domain=-7:2-0.1, samples=50, ultra thick, darkgray] {\FunctionF(x)};
        \addplot [domain=2+0.1:7, samples=50, ultra thick, darkgray] {\FunctionF(x)};
        \node [right, darkgray, thick] at (axis cs: 3,2) {$f(x)$};

        %g(x)
        \addplot [domain=-7:7, samples=20, ultra thick, magenta, densely dashed] {\FunctionG(x)};
      \end{axis}
    \end{tikzpicture}
\end{document}

答案1

以下是使用图层的一种方法。set layers在图层中添加并绘制圆圈axis foreground，例如，

\begin{pgfonlayer}{axis foreground}
    \draw[magenta, thick, fill=white] (A) circle[radius=2pt];
    % y-intercept        
    \filldraw[magenta, thick] (B) circle [radius=2pt];
\end{pgfonlayer}

完整示例

\documentclass[12pt]{extarticle}
\usepackage{tikz}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}

\pgfplotsset{vasymptote/.style={
    before end axis/.append code={
        \draw[densely dashed, magenta] ({rel axis cs:0,0} -| {axis cs:#1,0})
        -- ({rel axis cs:0,1} -| {axis cs:#1,0});
    }
}}

\begin{document}
    \begin{tikzpicture}
      \def\FunctionF(#1){(#1+2)/((#1)^2-4)}
      \def\FunctionG(#1){0}
      \begin{axis}[
        axis y line=center,
        axis x line=middle, 
        axis on top=false,
        xmin=-6.5, xmax=6.5,
        ymin=-6.5, ymax=6.5,
        grid,
        xtick={-6,...,6},
        ytick={-6,...,6},
        yticklabels={-6,,-4,,-2,,,,2,,4,,6},
        xticklabels={-6,,-4,,-2,,,,2,,4,,6},
        vasymptote=2,
        set layers%<- added
        ]

        % Hole
        \coordinate (A) at (-2,-1/4);   
        % y-intercept        
        \coordinate (B) at (0,-1/2);

        % Hole 
        \begin{pgfonlayer}{axis foreground}
        \draw[magenta, thick, fill=white] (A) circle[radius=2pt];
        % y-intercept        
        \filldraw[magenta, thick] (B) circle [radius=2pt];
        \end{pgfonlayer}

        % f(x)
        \addplot [domain=-7:2-0.1, samples=50, ultra thick, darkgray] {\FunctionF(x)};
        \addplot [domain=2+0.1:7, samples=50, ultra thick, darkgray] {\FunctionF(x)};
        \node [right, darkgray, thick] at (axis cs: 3,2) {$f(x)$};

        %g(x)
        \addplot [domain=-7:7, samples=20, ultra thick, magenta, densely dashed] {\FunctionG(x)};
      \end{axis}
    \end{tikzpicture}
\end{document}

在此处输入图片描述

您也可以直接在图后画圆圈。

    \addplot [domain=-7:2-0.1, samples=50, ultra thick, darkgray] {\FunctionF(x)};
    \addplot [domain=2+0.1:7, samples=50, ultra thick, darkgray] {\FunctionF(x)};
    \node [right, darkgray, thick] at (axis cs: 3,2) {$f(x)$};

    %g(x)
    \addplot [domain=-7:7, samples=20, ultra thick, magenta, densely dashed] {\FunctionG(x)};
    % Hole 
    \draw[magenta, thick, fill=white] (A) circle[radius=2pt];
    % y-intercept        
    \filldraw[magenta, thick] (B) circle [radius=2pt];

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