双线交点

Question

double line我尝试用其他颜色填充两个 s 的交集，但没有成功。以下是最简单的工作示例：

\documentclass{standalone}
\usepackage{tikz}


\begin{document}
    \begin{tikzpicture}

        \node (Emetteur) at (0,0) {};
        \node (Recepteur) at (2.5,0) {};
        \node (Recepteur2) at (-2.5,0) {};
        \node (Cible) at (1,3) {};

        \draw [black!15, double = black!15, double distance = 5] (1.25,0) ellipse (6cm and 3.025cm);
        \draw [black!15, double = black!15, double distance = 5] (-1.25,0) ellipse (6cm and 3.25cm);

        \draw (-4,0) -- (4,0);
        \draw (Emetteur) node {$\bullet$} node [below] {\'Emetteur};
        \draw (Recepteur) node {$\bullet$} node [below] {R\'ecepeur 1};
        \draw (Recepteur2) node {$\bullet$} node [below] {R\'ecepeur 2};
        \draw (Cible) node {$\bullet$} node [above=0.1cm, align = center] {Cible};

        \draw [blue] (Emetteur) -- (Cible) node [midway, sloped, above] {$d_1$};
        \draw [red] (Cible) -- (Recepteur) node [pos = 0.5, sloped, above] {$d_2$}; 
        \draw [green!50!black] (Cible) -- (Recepteur2) node [pos = 0.5, sloped, above] {$d_3$}; 


    \end{tikzpicture}
\end{document}

我得到以下结果：

我找到了一种使用该opacity选项的方法：

    \draw [black!15, double = black!50, double distance = 5, opacity = 0.2] (1.25,0) ellipse (6cm and 3.025cm);
    \draw [black!15, double = black!50, double distance = 5, opacity = 0.2] (-1.25,0) ellipse (6cm and 3.25cm);

然后我得到：

这只是一个技巧，因为两个透明形状的叠加会产生另一种颜色，但我宁愿避免这种opacity选择，因为打印时渲染效果很差，而且我无法得到我想要的颜色的交集。

有什么线索吗？

Answer 1

您可以使用blending

\begin{scope}[blend group=multiply]
        \draw [black!15, double = black!15, double distance = 5] (1.25,0) ellipse (6cm and 3.025cm);
        \draw [black!15, double = black!15, double distance = 5] (-1.25,0) ellipse (6cm and 3.25cm);
\end{scope}

完整代码：

\documentclass{standalone}
\usepackage{tikz}


\begin{document}
    \begin{tikzpicture}

        \node (Emetteur) at (0,0) {};
        \node (Recepteur) at (2.5,0) {};
        \node (Recepteur2) at (-2.5,0) {};
        \node (Cible) at (1,3) {};
       \begin{scope}[blend group=multiply]
        \draw [black!15, double = black!15, double distance = 5] (1.25,0) ellipse (6cm and 3.025cm);
        \draw [black!15, double = black!15, double distance = 5] (-1.25,0) ellipse (6cm and 3.25cm);
    \end{scope}

        \draw (-4,0) -- (4,0);
        \draw (Emetteur) node {$\bullet$} node [below] {\'Emetteur};
        \draw (Recepteur) node {$\bullet$} node [below] {R\'ecepeur 1};
        \draw (Recepteur2) node {$\bullet$} node [below] {R\'ecepeur 2};
        \draw (Cible) node {$\bullet$} node [above=0.1cm, align = center] {Cible};

        \draw [blue] (Emetteur) -- (Cible) node [midway, sloped, above] {$d_1$};
        \draw [red] (Cible) -- (Recepteur) node [pos = 0.5, sloped, above] {$d_2$};
        \draw [green!50!black] (Cible) -- (Recepteur2) node [pos = 0.5, sloped, above] {$d_3$};


    \end{tikzpicture}
\end{document}