从同一中心点按顺序显示圆圈

Question

我想绘制按顺序显示的同心圆。

应用以下代码时，每个圆圈显示时，圆圈似乎从顶部边缘向下移动。

如何避免这种情况并使它们从同一中心坐标叠加显示，如本图所示。

\documentclass{beamer}
\beamertemplatenavigationsymbolsempty
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{tkz-fct}
\usetikzlibrary{fadings}
\begin{document}
\begin{frame}[fragile,t]
\frametitle{}
\begin {center}
\begin{tikzpicture}[scale=.9, transform shape]
  \only<1,5>
{
\node[circle, outer color=yellow!60!green, inner color=white, minimum width=5cm] (radial) at (4,0) {};
\fill[pattern=dots,pattern color = black] (3.6,-.4) -- + +(.8,0) -- ++ (0,.8) -- ++(-.8,0) -- cycle;
}
  \only<4-5>
{
\node[circle, outer color=green!80!purple, inner color=purple, minimum width=4cm] (radial) at (4,0) {};
}
  \only<3-5>
{
\node[circle, outer color=purple, inner color=purple!20!red, minimum width=3cm] (radial) at (4,0) {};
}
  \only<2-5>
{
\node[circle, outer color=purple, inner color=purple!50!black, minimum width=2cm] (radial) at (4,0) {};
}
\end{tikzpicture}
\end {center}
\end{frame}
\end{document}

Answer 1

一个粗鲁的解决方案是给每张幻灯片添加minimum size最大的一个隐形圆圈：

\documentclass{beamer}
\beamertemplatenavigationsymbolsempty
\usepackage{tikz}
\usetikzlibrary{fadings, patterns}

\begin{document}
\begin{frame}[fragile,t]
\frametitle{Circles \dots}
\begin {center}
\begin{tikzpicture}[scale=.9,
circ/.style args = {#1/#2/#3}{circle,outer color=#1, inner color=#2, minimum width=#3,
                              node contents={}},
                    ]
  \only<1,5>
{
\node[circ=yellow!60!green/white/5cm];
\fill[pattern=dots,pattern color = black] (-0.4,-0.4) rectangle + (0.8,0.8);
}
  \only<4-5>
{
\node[circle, minimum size=5cm] {};
\node[circ=green!80!purple/purple/4cm];
}
  \only<3-5>
{
\node[circle, minimum size=5cm] {};
\node[circ=purple/purple!20!red/3cm];
}
  \only<2-5>
{
\node[circle, minimum size=5cm] {};
\node[circ=purple/purple!50!black/2cm];
}
\end{tikzpicture}
\end {center}
\end{frame}
\end{document}

笔记：

• 中的坐标tikzpicure是相对于图片的，而不是幻灯片的。因此，在您的情况下，如果省略坐标的明确符号，则会at (4,0)产生相同的结果。at (0,0)

• 为了确定幻灯片上绝对位置的坐标，您需要使用remember picture, overlay：

  \documentclass{beamer}
  \beamertemplatenavigationsymbolsempty
  \usepackage{tikz}
  \usetikzlibrary{calc, fadings, patterns,
                  overlay-beamer-styles}
  
  \begin{document}
  \begin{frame}[fragile,t]
  \frametitle{Circles \dots}
  \begin{tikzpicture}[remember picture,overlay,
  circ/.style args = {#1/#2/#3}{circle,outer color=#1, inner color=#2, minimum width=#3},
                      ]
    \only<1,5>
  {
  \node[circ=yellow!60!green/white/5cm] (center) at (current page.center) {};
  \fill[pattern=dots,pattern color = black]
      ($(current page.center)+(-0.4,-0.4)$) rectangle + (0.8,0.8);
  }
    \only<4-5>
  {
  \node[circ=green!80!purple/purple/4cm] at (center) {};
  }
    \only<3-5>
  {
  \node[circ=purple/purple!20!red/3cm] at (center) {};;
  }
    \only<2-5>
  {
  \node[circ=purple/purple!50!black/2cm] at (center) {};;
  }
  \end{tikzpicture}
  \end{frame}
  \end{document}
  

Answer 2

图书馆的一个不太粗鲁的解决方案beamer-overlay-styles。

\documentclass{beamer}
\beamertemplatenavigationsymbolsempty
\usepackage{tikz}
\usetikzlibrary{overlay-beamer-styles} %<-added
\usepackage{pgfplots}
\usepackage{tkz-fct}
\usetikzlibrary{fadings}
\begin{document}
\begin{frame}[fragile,t]
\frametitle{Circles with the \texttt{overlay-beamer-styles} library}
\begin {center}
\begin{tikzpicture}[scale=.9, transform shape]
\node[visible on=<{1,5}>,circle, outer color=yellow!60!green, inner color=white, minimum width=5cm] (radial) at (4,0) {};
\fill[visible on=<{1,5}>,pattern=dots,pattern color = black] (3.6,-.4) -- + +(.8,0) -- ++ (0,.8) -- ++(-.8,0) -- cycle;
\node[visible on=<{4-5}>,circle, outer color=green!80!purple, inner color=purple, minimum width=4cm] (radial) at (4,0) {};
\node[visible on=<{3-5}>,circle, outer color=purple, inner color=purple!20!red, minimum width=3cm] (radial) at (4,0) {};
\node[visible on=<{2-5}>,circle, outer color=purple, inner color=purple!50!black, minimum width=2cm] (radial) at (4,0) {};
\end{tikzpicture}
\end {center}
\end{frame}
\end{document}