Pgfplots 轮廓/轴在顶部 = false

Question

尽管axis on top = false有选择，但以下 MWE 中的 0 轮廓线（即 x=0 方程线）并未出现。有解决办法吗？

\documentclass[12pt]{article}

\usepackage{tikz}
\usepackage{pgfplots}

\begin{document}

\begin{tikzpicture}
    \begin{axis}[axis lines=center, axis on top=false, domain=-2:2, y domain=-1.5:1.5,
            view = {0}{90}, colorbar]
        \addplot3[contour gnuplot={labels=false,
                levels={-0.2, -0.1, 0, 0.1, 0.2}},
                samples=100]{x*exp(-x^2-y^2))};
    \end{axis}
\end{tikzpicture}

\end{document}

Answer 1

根据这个答案https://tex.stackexchange.com/a/450780/263192，set layers并on layer=axis foreground解决了这个问题。

\documentclass[12pt]{article}

\usepackage{pgfplots}
\pgfplotsset{compat=1.18}

\begin{document}

\begin{tikzpicture}
    \begin{axis}[
        axis lines=center,
        set layers,
        domain=-2:2,
        y domain=-1.5:1.5,
        view = {0}{90},
        colorbar
    ]
    \addplot3[
        on layer=axis foreground,
        contour gnuplot={
            labels=false,
            levels={-0.2, -0.1, 0, 0.1, 0.2}
        },
        samples=100
    ] {x*exp(-x^2-y^2))};
    \end{axis}
\end{tikzpicture}

\end{document}