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TikZ：裁剪和阴影或填充绘图

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TikZ：裁剪和阴影或填充绘图

我重写了三个月前写的一些代码椭圆和直线之间的填充

然而，无论我怎么尝试，我都无法填充较小的三角形。

到目前为止我已经尝试过：

\begin{scope}                                                                  
 \clip (S) -- (F) -- (V) -- (S);                                              
 \filldraw[bottom color = cyan!50!blue, top color = green!20]                 
 (S) -- (F) -- (V) -- (S);                                                    
\end{scope}

和

\begin{scope}                                                                  
  \clip (S) -- (F) -- (V) -- cycle;                                              
  \filldraw[bottom color = cyan!50!blue, top color = green!20]                 
  (S) -- (F) -- (V) -- (S);                                                    
\end{scope}

和

\begin{scope}                                                                  
      \clip (S) -- (F) -- (V) -- cycle;                                              
      \filldraw[bottom color = cyan!50!blue, top color = green!20]                 
      (S) rectangle (V) -- (S);                                                    
    \end{scope}

我尝试了更多方法，但我不会全部列出。新代码是：

\documentclass{article}
  \usepackage{tikz}
  \usetikzlibrary{cal, intersections, arrows}
  \begin{document}
  \begin{tikzpicture}[
    every label/.append style = {font = \small},
    dot/.style = {outer sep = +0pt, inner sep = +0pt, shape = circle,
      draw = black, label = {#1}},
    small dot/.style = {minimum size = .05cm, dot = {#1}},
    big dot/.style = {minimum size = .1cm, dot = {#1}},
    extended line/.style = {shorten >=-#1, shorten <=-#1},
    extended line/.default = 1cm,
    one end extended/.style = {shorten >=-#1},
    one end extended/.default = 1.25cm, line cap = round, line join = round,
    >=triangle 45]
    \pgfmathsetmacro{\a}{3}
    \pgfmathsetmacro{\b}{2.5}
    \pgfmathsetmacro{\c}{sqrt(\a^2 - \b^2)}

    \node[fill = black, big dot = {below left: \(A\)}] (A) at (-3, 0) {};
    \node[fill = black, big dot = {below right: \(P\)}] (P) at (3, 0) {};
    \node[fill = black, big dot = {below left: \(D\)}] (D) at (0, -2.5) {};
    \node[fill = black, big dot = {above left: \(B\)}] (B) at (0, 2.5) {};
    \node[fill = black, big dot = {below left: \(F\)}] (F) at (\c, 0) {};
    \node[fill = black, big dot = {below left: \(O\)}] (O) at (0,0) {};

    \draw (0, -3.25) -- (0, 3.25) node[scale = .75, fill = white,
    inner sep = 0cm, pos = .7] {\(b\)};
    \draw[name path = xline] (-3.25, 0) -- (5, 0) node[scale = .8, fill = white,
    inner sep = 0cm, pos = .2] {\(a\)};
    \draw[red, name path = circle] (O) circle (3cm);
    \draw[blue, name path = ellipse] (O) ellipse (3cm and 2.5cm);
    \path[name path = line] (2.25, 3) -- (2.25, -1);

    \path[name intersections = {of = circle and line, by = P1}];
    \node[fill = black, big dot = {above: \(Q\)}] (Q) at (P1) {};
    \path[name intersections = {of = line and xline, by = P2}];

    \draw[black] (Q) -- (P2) node[fill = black, big dot = {below right: \(V\)}]
    (V) at (P2) {};
    \path[name intersections = {of = line and ellipse, by = P3}];
    \node[fill = black, big dot = {right: \(S\)}] (S) at (P3) {};

    \draw (O) -- (Q) node[scale = .75, pos = .5, fill = white, inner sep = 0cm]
    {\(a\)};
    \draw[one end extended] (F) -- (S) node[scale = .8, pos = .5,
    fill = white, inner sep = 0.03cm] {\(r\)};

    \begin{scope}
      \clip (S) rectangle (P);
      \shadedraw[blue, outer color = blue!30!black, inner color = red!30]
      (O) ellipse (3cm and 2.5cm);
    \end{scope}
  \end{tikzpicture}
  \end{document}

在此处输入图片描述

所以无论我做什么，我都无法填写(S) -- (F) -- (V) -- cycle

答案1

问题是S，F和V是节点而不是坐标。

你看，当你用--（或任何其他路径操作符）连接节点时，TikZ 会注意你只连接它们的边界。

如果你

\draw[green,thick] (S) -- (F) -- (V) -- cycle;

你会得到

在此处输入图片描述

TikZ 会小心地连接节点。但这不会创建一个封闭的区域（该-- cycle操作符似乎也没有任何效果，因为最后存储的移动到点将位于从到的V线绘制之后。）这通常是您想要的（用于在节点之间绘制线）。FV

但就你的情况而言，你想创建一个封闭区域。我假设你想使用center节点的锚点，因为……嗯，这可能是唯一明智的解决方案。

我还建议使用backgrounds库和on backgrounds layer样式来确保区域（实际上都是）都将被绘制在下面线和节点。

代码

\documentclass[tikz,convert=false]{standalone}
\usetikzlibrary{intersections, arrows, backgrounds}
\begin{document}
\begin{tikzpicture}[
    every label/.append style = {font = \small},
    dot/.style = {inner sep = +0pt, shape = circle,
      draw = black, label = {#1}},
    small dot/.style = {minimum size = .05cm, dot = {#1}},
    big dot/.style = {minimum size = .1cm, dot = {#1}},
    extended line/.style = {shorten >=-#1, shorten <=-#1},
    extended line/.default = 1cm,
    one end extended/.style = {shorten >=-#1},
    one end extended/.default = 1.25cm, line cap = round, line join = round,
    >=triangle 45]
    \pgfmathsetmacro{\a}{3}
    \pgfmathsetmacro{\b}{2.5}
    \pgfmathsetmacro{\c}{sqrt(\a^2 - \b^2)}

    \node[fill = black, big dot = {below left: \(A\)}] (A) at (-3, 0) {};
    \node[fill = black, big dot = {below right: \(P\)}] (P) at (3, 0) {};
    \node[fill = black, big dot = {below left: \(D\)}] (D) at (0, -2.5) {};
    \node[fill = black, big dot = {above left: \(B\)}] (B) at (0, 2.5) {};
    \node[fill = black, big dot = {below left: \(F\)}] (F) at (\c, 0) {};
    \node[fill = black, big dot = {below left: \(O\)}] (O) at (0,0) {};

    \draw (0, -3.25) -- (0, 3.25) node[scale = .75, fill = white,
    inner sep = 0cm, pos = .7] {\(b\)};
    \draw[name path = xline] (-3.25, 0) -- (5, 0) node[scale = .8, fill = white,
    inner sep = 0cm, pos = .2] {\(a\)};
    \draw[red, name path = circle] (O) circle (3cm);
    \draw[blue, name path = ellipse] (O) ellipse (3cm and 2.5cm);
    \path[name path = line] (2.25, 3) -- (2.25, -1);

    \path[name intersections = {of = circle and line, by = P1}];
    \node[fill = black, big dot = {above: \(Q\)}] (Q) at (P1) {};
    \path[name intersections = {of = line and xline, by = P2}];

    \draw[black] (Q) -- (P2) node[fill = black, big dot = {below right: \(V\)}]
    (V) at (P2) {};
    \path[name intersections = {of = line and ellipse, by = P3}];
    \node[fill = black, big dot = {right: \(S\)}] (S) at (P3) {};

    \draw (O) -- (Q) node[scale = .75, pos = .5, fill = white, inner sep = 0cm]
    {\(a\)};
    \draw[one end extended] (F) -- (S) node[scale = .8, pos = .5,
    fill = white, inner sep = 0.03cm] {\(r\)};

    \begin{scope}[on background layer]
      \begin{scope}
        \clip (S) rectangle (P);
        \shadedraw[blue, outer color = blue!30!black, inner color = red!30] (O) ellipse (3cm and 2.5cm);
      \end{scope}
      \filldraw[bottom color = cyan!50!blue, top color = green!20] (S.center) -- (F.center) -- (V.center) -- cycle;
    \end{scope}
\end{tikzpicture}
\end{document}

输出

在此处输入图片描述

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