pgflayer：背景和前景和 tikz：水的图案

Question

我正在尝试画一个漂浮在水中的桶。我尝试使用pgfonlayer这样一种方式：当水线与桶相交时，水线将被移除。

另外，我浏览了手册中有关图案的一小部分，但找不到适合水的图案。

这是我想重新创建的图像：

这是我的代码和图像：

\documentclass[tikz]{standalone}
\usetikzlibrary{patterns}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,foreground}

\begin{document}
\begin{tikzpicture}
  \begin{pgfonlayer}{foreground}
    % draw a barrel
    \draw (0, 0) ellipse[x radius = 1.5cm, y radius = 0.5cm]
    coordinate (B) at (-1.5cm, 0) coordinate (A) at (1.5cm, 0);
    \draw[dashed] (-1.5cm, -1cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw[dashed] (-1.5cm, -1.1cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw[dashed] (-1.5cm, -2cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw[dashed] (-1.5cm, -2.1cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw (-1.5cm, -3cm) coordinate (C) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360] coordinate (D);
    \draw (A) -- (D);
    \draw (B) -- (C);

    % draw the direction of the W = mg
    \fill[black] (0, -1.85cm) coordinate (W) circle[radius = 0.025cm];
    \draw[-stealth] (W) -- ++(0, -0.35cm) node[right, font = \scriptsize] {$mg$};

    % draw the barrel dimensions
    \begin{scope}[>=stealth]
      \draw[|<->|] (-1.5cm, 1cm) -- ++(3cm, 0) node[pos = 0.5,
      fill = white, font = \scriptsize, inner sep = 0.05cm] {$d$};
      \draw[|<->|] (-2cm, 0cm) -- ++(0, -3.5cm) node[pos = 0.5,
      fill = white, font = \scriptsize, inner sep = 0.05cm] {$\ell$};
    \end{scope}
  \end{pgfonlayer}

  % draw the water
  \begin{pgfonlayer}{background}
    \draw (-2.5cm, -1.5cm) -- ++(7cm, 0);
  \end{pgfonlayer}
\end{tikzpicture}
\end{document}

Answer 1

我重新绘制了圆柱体并用 填充它，white这样在background图层上绘制的任何内容都不可见。此外，通过操纵dash pattern并使用\foreach一些 循环xshift，可以实现所需的效果。

\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{patterns}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,foreground}

\begin{document}
\begin{tikzpicture}
  \begin{pgfonlayer}{foreground}
    % draw a barrel
    \draw[fill=white] (-1.5cm, 0) -- (-1.5cm, -3cm) coordinate (C) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360] coordinate (D) -- (1.5cm, 0) --(-1.5cm, 0) -- cycle;
%    \draw[red] (A) -- (D);
%    \draw[red] (B) -- (C);
    \draw[fill=white] (0, 0) ellipse[x radius = 1.5cm, y radius = 0.5cm]
    coordinate (B) at (-1.5cm, 0) coordinate (A) at (1.5cm, 0);
    \draw[dashed] (-1.5cm, -1cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw[dashed] (-1.5cm, -1.1cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw[dashed] (-1.5cm, -2cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];
    \draw[dashed] (-1.5cm, -2.1cm) arc[x radius = 1.5cm, y radius = 0.5cm,
    start angle = 180, end angle = 360];


    % draw the direction of the W = mg
    \fill[black] (0, -1.85cm) coordinate (W) circle[radius = 0.025cm];
    \draw[-stealth] (W) -- ++(0, -0.35cm) node[right, font = \scriptsize] {$mg$};

    % draw the barrel dimensions
    \begin{scope}[>=stealth]
      \draw[|<->|] (-1.5cm, 1cm) -- ++(3cm, 0) node[pos = 0.5,
      fill = white, font = \scriptsize, inner sep = 0.05cm] {$d$};
      \draw[|<->|] (-2cm, 0cm) -- ++(0, -3.5cm) node[pos = 0.5,
      fill = white, font = \scriptsize, inner sep = 0.05cm] {$\ell$};
    \end{scope}
  \end{pgfonlayer}

  % draw the water
  \begin{pgfonlayer}{background}
    \draw[dash pattern=on 20pt off 10pt] (-2.5cm, -1.5cm) -- ++(6cm, 0);
    \foreach \x in {-1.7,-1.9,...,-4.1}{
      \draw[gray!30,dash pattern=on 4pt off 4pt] ([xshift=4pt]-2.5cm, \x cm) -- ++([xshift=-4pt]6cm, 0);
    }
    \foreach \x in {-1.6,-1.8,...,-4}{
      \draw[gray!30,dash pattern=on 4pt off 4pt] (-2.5cm, \x cm) -- ++(6cm, 0);
    }
  \end{pgfonlayer}
\end{tikzpicture}
\end{document}