使用 tcolorbox 时如何在两个不同的幻灯片中固定方程的位置？

Question

我正在尝试使方程式动起来。以下是我所做的。

\documentclass[9pt,final,leg,aspectratio=169,landscape]{beamer}

\usepackage{tikz}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathtools}
\usepackage[absolute,overlay]{textpos}
\usepackage[skins,theorems]{tcolorbox}
\tcbset{highlight math style={enhanced,
  colframe=red,colback=white,arc=0pt,boxrule=0.75pt}}

\begin{document}

\begin{frame}
    \begin{itemize}
        \item \textbf{Governing Equations:}\vspace{1.5ex}
        \begin{itemize}
            \item Mass continuity:
            \begin{overprint}
                \onslide<1>
                \begin{equation}
                    \small{\frac{d}{dz} (\rho u) \; + \; 2 \rho V \; = \; 0  }
                \end{equation}\vspace{1.5ex}
                \item Radial momentum:
                \begin{equation}
                    \small{\rho u\frac{dV}{dz} \; + \; \rho V^2 \; = \; -\Lambda \; + \; \frac{d}{dz} \left( \mu     \frac{dV}{dz}\right) }
                \end{equation}
                \onslide<2>
                \begin{equation}
                    \tcbset{highlight math/.append style={left=-1.35mm,right=-1mm,top=0mm,bottom=0mm}}
                    \small{\frac{d}{dz} (\rho u) \; + \; 2 \rho \underset{\let\scriptstyle\textstyle
                    \substack{v/r}}{\tcbhighmath{V}} \; = \; 0  }
                \end{equation}\vspace{1.5ex}
                \item Radial momentum:
                \begin{equation}
                    \tcbset{highlight math/.append style={left=-1mm,right=-1mm,top=0mm,bottom=0mm}}
                    \small{\rho u\frac{dV}{dz} \; + \; \rho V^2 \; = \; -\underset{\let\scriptstyle\textstyle
                    \substack{\frac{1}{r} \frac{dp}{dr}}}{\tcbhighmath{\Lambda}} \; + \; \frac{d}{dz} \left( \mu \frac{dV}{dz}\right) }
                \end{equation}
            \end{overprint}
        \end{itemize}
    \end{itemize}
    
\end{frame}


\end{document}

结果（动画）

但事实上，问题是当我添加方框来描述某些术语时，方程的位置会发生变化。但我希望方程在两张幻灯片中的位置保持不变，尽管在它们周围添加了额外的细节。

Answer 1

您可以使用该hf-tikz包：

\documentclass[9pt,final,leg,aspectratio=169,landscape]{beamer}

\usepackage{tikz}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathtools}
\usepackage[absolute,overlay]{textpos}
\usepackage[skins,theorems]{tcolorbox}
\tcbset{highlight math style={enhanced,
  colframe=red,colback=white,arc=0pt,boxrule=0.75pt}}
  
\usetikzlibrary{overlay-beamer-styles}
\usepackage[beamer,customcolors]{hf-tikz}
\hfsetfillcolor{white}
\hfsetbordercolor{red}
\tikzset{h1/.style={
    disable rounded corners=true,
    above left offset={-0.1,0.4},
    below right offset={0.1,-0.05},
  },
} 

\begin{document}

\begin{frame}
    \begin{itemize}
        \item \textbf{Governing Equations:}\vspace{1.5ex}
        \begin{itemize}
            \item Mass continuity:
                \begin{equation}
                    \small{\frac{d}{dz} (\rho u) \; + \; 2 \rho \underset{\let\scriptstyle\textstyle
                    \visible<2->{\substack{v/r}}}{\tikzmarkin<2->[h1]{a1}V\tikzmarkend{a1}} \; = \; 0  }
                \end{equation}\vspace{1.5ex}
                \item Radial momentum:
                \begin{equation}
                    \small{\rho u\frac{dV}{dz} \; + \; \rho V^2 \; = \; -\underset{\let\scriptstyle\textstyle
                    \substack{\visible<2->{\frac{1}{r} \frac{dp}{dr}}}}{\tikzmarkin<2->[h1]{a2}\Lambda\tikzmarkend{a2}} \; + \; \frac{d}{dz} \left( \mu \frac{dV}{dz}\right) }
                \end{equation}
        \end{itemize}
    \end{itemize}
    
\end{frame}


\end{document}