Pgfplots ybar 带有褪色的颜色

Question

我正在尝试生成一个 ybar 图，其中每个条形从淡入淡出再变回透明。我希望每个条形在开始时都是完全透明的颜色，在结束时再次完全透明。现在看来，淡入淡出只需设置一次即可应用于所有条形。

我如何为每个条形单独设置淡入淡出效果？有什么想法吗？

谢谢你！

\documentclass [tikz] {standalone}

\usepackage{pgfplots}
\usetikzlibrary{fadings}

\begin{document}
\begin{tikzpicture}[ >=stealth]

    \begin{axis}[xbar stacked,
    axis lines*=left,
    width=15cm, height=6cm,
    xtick = {1,10},
    xmin=1, xmax=10,
    xmode=log,
    xmajorgrids=true, xminorgrids=true, minor tick num=1,
    ymajorgrids=false, yminorgrids=false,
    bar width=15pt,
    symbolic y coords={One,Two,Three,Four},
    ]

    \addplot[draw = none] coordinates % Invisible 1. bar
        {(1,One) (2,Two) (2,Three) (2,Four)};

    \addplot[draw = none, fill=blue!30!black, path fading=west] coordinates
        {(1,One) (2,Two) (2,Three) (2,Four)};

    \addplot[draw = none, fill=blue!30!black] coordinates
        {(1,One) (2,Two) (2,Three) (2,Four)};

    \addplot[draw = none, fill=blue!30!black, path fading=east] coordinates
        {(1,One) (2,Two) (2,Three) (2,Four)};

    \end{axis}

\end{tikzpicture}
\end{document}