如何改变 TikZ 淡入淡出的强度？

Question

我正在尝试使用 TikZ 淡入淡出来实现镜像/反射效果，但我目前能够实现的淡入淡出太“温和”了 - 线条淡入淡出，但所有线条都保留了下来。线条的反射本身处于正确的位置，但淡入淡出的强度不够 - 我希望线条很快消失。

这是我的 MWE：

\documentclass[11pt,twoside]{book}

\usepackage{tikz} 
\usetikzlibrary{fadings}
\usepackage{afterpage}
\usepackage{xcolor}
\usepackage{geometry}

\geometry{
    paperwidth=17.78cm,
    paperheight=25.4cm,
    marginparsep=6.35mm,
    top=.5cm, % Top margin
    bottom=1cm, % Bottom margin
    left=2cm, % Left margin
    right=2cm, % Right margin
}

% Adds bleed
\usepackage[
width=18.0975cm,
height=26.035cm,
center,
%cam,
%cross,
%frame
]{crop}

\begin{document}
    \begin{titlepage}
        \pagecolor{orange}\afterpage{\nopagecolor}

        \begin{tikzpicture}
        \draw[overlay, white, line width=1.1mm] (-3,-.35) .. controls (-2.5,-4.5) and (5,-3.5) .. (20,.5);
        \begin{scope}[shift={(0,-6.15)},xscale=1,yscale=-1,rotate=360]
        \draw[overlay, white, line width=1.1mm,path fading=south] (-3,-.35) .. controls (-2.5,-4.5) and (5,-3.5) .. (20,.5);  % Mirror Image
        \end{scope}
        \end{tikzpicture}
    \end{titlepage}
\end{document}

由此产生了如下结果：

这就是我想要达到的效果：

使用 TikZ 可以实现我想要的效果吗？

非常感谢您提前提供的任何帮助。

Answer 1

你可以查阅原始南方淡入的定义pgflibraryfadings.code.tex来找到

\pgfdeclareverticalshading{pgf@lib@fade@south}{100bp}
{color(0bp)=(pgftransparent!100); color(25bp)=(pgftransparent!100);
color(75bp)=(pgftransparent!0); color(100bp)=(pgftransparent!0)}%

\pgfdeclarefading{south}{\pgfuseshading{pgf@lib@fade@south}}%

我所做的就是换成color(25bp)=(pgftransparent!100);在color(40bp)=(pgftransparent!100);渐隐中我呼叫South的

\documentclass[11pt,twoside]{book}

\usepackage{tikz} 
\makeatletter
\pgfdeclareverticalshading{pgf@lib@fade@South}{100bp}
{color(0bp)=(pgftransparent!100); color(40bp)=(pgftransparent!100);
 color(75bp)=(pgftransparent!0); color(100bp)=(pgftransparent!0)}%
\pgfdeclarefading{South}{\pgfuseshading{pgf@lib@fade@South}}%
\makeatother
\usetikzlibrary{fadings}
\usepackage{afterpage}
\usepackage{xcolor}
\usepackage{geometry}

\geometry{
    paperwidth=17.78cm,
    paperheight=25.4cm,
    marginparsep=6.35mm,
    top=.5cm, % Top margin
    bottom=1cm, % Bottom margin
    left=2cm, % Left margin
    right=2cm, % Right margin
}

% Adds bleed
\usepackage[
width=18.0975cm,
height=26.035cm,
center,
%cam,
%cross,
%frame
]{crop}

\begin{document}
    \begin{titlepage}
        \pagecolor{orange}\afterpage{\nopagecolor}

        \begin{tikzpicture}
        \draw[overlay, white, line width=1.1mm] (-3,-.35) .. controls (-2.5,-4.5) and (5,-3.5) .. (20,.5);
        \begin{scope}[shift={(0,-6.15)},xscale=1,yscale=-1,rotate=360]
        \draw[overlay, white, line width=1.1mm,path fading=South] 
        (-3,-.35) .. controls (-2.5,-4.5) and (5,-3.5) .. (20,.5);  % Mirror Image
        \end{scope}
        \end{tikzpicture}
    \end{titlepage}
\end{document}

而50bp不是40bp你得到