I want to create a slide to show how the clipping works as shown in the following animation.

I used two frames, the last frame is needed because I want to hide the unwanted (trimmed) parts of cropped areas of the previous slides. I want to avoid using two frames and repeating the codes.
Can we force beamer to delay the clipping code and hiding the previous painting? I am new to beamer, only knows \pause. :-)
\documentclass{beamer}
\usepackage{pstricks-add}
\usepackage[active,tightpage]{preview}
\PreviewBorder=0pt
\PreviewEnvironment{pspicture}
\begin{document}
\begin{frame}
\begin{pspicture}(6,6)
\pnode(0,0){A}
\pnode(6,0){B}
\pnode(6,6){C}
\pnode(0,6){D}
\pnode(1,1){P}
\pnode(5,1){Q}
\pnode(3,5){R}
\pspolygon*[linecolor=red](A)(B)(Q)(P)\pause
\pspolygon*[linecolor=green](B)(C)(R)(Q)\pause
\pspolygon*[linecolor=blue](C)(D)(R)\pause
\pspolygon*[linecolor=yellow](D)(A)(P)(R)
\end{pspicture}
\end{frame}
\begin{frame}
\begin{pspicture}(6,6)
\pnode(0,0){A}
\pnode(6,0){B}
\pnode(6,6){C}
\pnode(0,6){D}
\pnode(1,1){P}
\pnode(5,1){Q}
\pnode(3,5){R}
\psclip{\pscircle[linestyle=none,dimen=middle](3,3){3}}
\pspolygon*[linecolor=red](A)(B)(Q)(P)
\pspolygon*[linecolor=green](B)(C)(R)(Q)
\pspolygon*[linecolor=blue](C)(D)(R)
\pspolygon*[linecolor=yellow](D)(A)(P)(R)
\endpsclip
\end{pspicture}
\end{frame}
\end{document}


\uncover,\only,\onslide, etc for my problem above? – kiss my armpit Oct 18 '12 at 09:48