投影機疊印環境改變項目的垂直間距

Question

我有一個帶有環境的框架itemize，其中每個環境都\item包含一個方程式。然而，有些方程會發生變化，因此我將它們包裝在一個overprint環境中，以便出現一個方程，然後被另一個方程取代。這工作得很好，但項目的垂直間距並不理想，如下所示。 比較方程式與下一項 之間的空間以及方程式與下一項之間的空間。如何修正這個問題？或是否需要手動完成或類似的操作？\phi_a\phi_f\vspace

這是 MWE：

\documentclass[utf8]{beamer}
\begin{document}
\begin{frame}
\begin{itemize}
\item A NBR 6118 define $\phi$ como composto por três parcelas:
\begin{equation*}
\phi = \phi_a + \phi_f + \phi_d
\end{equation*}
\item $\phi_a$ representa a deformação rápida;
\begin{equation*}
\phi_a = 0,8\left(1-\beta_1\left(t_0\right)\right)
\end{equation*}
\item $\phi_f$ representa a deformação lenta irreversível;
\begin{overprint}
\onslide<1>
\begin{equation*}
\phi_f = \phi_{f\infty}\left(\beta_f\left(t\right)-\beta_f\left(t_0\right)\right)
\end{equation*}
\onslide<2>
\begin{equation*}
\phi_f = \phi_{f\infty}\left(\beta_f\left(t_i\right)-\beta_f\left(t_{i-1}\right)\right)
\end{equation*}
\end{overprint}
\item $\phi_d$ representa a deformação lenta reversível.
\begin{overprint}
\onslide<1>
\begin{equation*}
\phi_d = 0,4\frac{t-t_0+20}{t-t_0+70}
\end{equation*}
\onslide<2>
\begin{equation*}
\phi_d = 0,4\left(\frac{t_i-t_0+20}{t_i-t_0+70}-\frac{t_{i-1}-t_0+20}{t_{i-1}-t_0+70}\right)
\end{equation*}
\end{overprint}
\end{itemize}
\end{frame}
\end{document}

Answer 1

overprint只能很好地處理相當簡單的情況。我懷疑這裡的使用並不算夠簡單，至少沒有進行某種調整。

overlayarea整個環境更易於使用itemize：

\documentclass[utf8]{beamer}
\begin{document}
  \begin{frame}
    \begin{overlayarea}{\linewidth}{.75\textheight}
      \begin{itemize}
        \item A NBR 6118 define $\phi$ como composto por três parcelas:
        \begin{equation*}
          \phi = \phi_a + \phi_f + \phi_d
        \end{equation*}
        \item $\phi_a$ representa a deformação rápida;
        \begin{equation*}
          \phi_a = 0,8\left(1-\beta_1\left(t_0\right)\right)
        \end{equation*}
        \item $\phi_f$ representa a deformação lenta irreversível;
          \only<1>{%
          \begin{equation*}
            \phi_f = \phi_{f\infty}\left(\beta_f\left(t\right)-\beta_f\left(t_0\right)\right)
          \end{equation*}}
        \only<2>{%
          \begin{equation*}
            \phi_f = \phi_{f\infty}\left(\beta_f\left(t_i\right)-\beta_f\left(t_{i-1}\right)\right)
          \end{equation*}}
        \item $\phi_d$ representa a deformação lenta reversível.
        \only<1>{%
          \begin{equation*}
            \phi_d = 0,4\frac{t-t_0+20}{t-t_0+70}
          \end{equation*}}
        \only<2>{%
          \begin{equation*}
            \phi_d = 0,4\left(\frac{t_i-t_0+20}{t_i-t_0+70}-\frac{t_{i-1}-t_0+20}{t_{i-1}-t_0+70}\right)
          \end{equation*}}
      \end{itemize}
    \end{overlayarea}
  \end{frame}
\end{document}