\begin{figure}[h!]
\begin{center}
\begin{tikzpicture}[scale=.6,tdplot_main_coords]
\begin{scope}[xshift=0cm,yshift=-2cm]
\draw[line width=2pt,->](.5,.5,1.5)--(.5,.5,0);
\end{scope}
\begin{scope}[xshift=0cm,yshift=0cm]
\clip(2,0,0)--(2,1,0)--(0,1,0)--(0,1,1)--(0,0,1)--(2,0,1)--cycle;
\draw[line width=1pt,fill=cyan]
(0,0,1)--(1,0,1)--(1,1,1)--(0,1,1)--cycle
(1,0,1)--(2,0,1)--(2,1,1)--(1,1,1)--cycle
;
\draw[line width=1pt,fill=black!20]
(2,0,1)--(2,0,0)--(2,1,0)--(2,1,1)--cycle
;
\draw[line width=1pt,fill=black!50]
(0,1,1)--(1,1,1)--(1,1,0)--(0,1,0)--cycle
(1,1,1)--(2,1,1)--(2,1,0)--(1,1,0)--cycle
;
\draw[line width=2pt](2,0,0)--(2,1,0)--(0,1,0)--(0,1,1)--(0,0,1)--(2,0,1)--cycle;
\end{scope}
%
\begin{scope}[xshift=0cm,yshift=-44mm]
\clip(2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,1)--(0,0,1)--(2,0,1)--cycle;
\draw[line width=1pt,fill=black!5]
(0,0,1)--(1,0,1)--(1,1,1)--(0,1,1)--cycle
(0,1,1)--(1,1,1)--(1,2,1)--(0,2,1)--cycle
(1,0,1)--(2,0,1)--(2,1,1)--(1,1,1)--cycle
(1,1,1)--(2,1,1)--(2,2,1)--(1,2,1)--cycle
;
\draw[line width=1pt,fill=black!20]
(2,0,1)--(2,0,0)--(2,1,0)--(2,1,1)--cycle
(2,1,1)--(2,1,0)--(2,2,0)--(2,2,1)--cycle
;
\draw[line width=1pt,fill=black!50]
(0,2,1)--(1,2,1)--(1,2,0)--(0,2,0)--cycle
(1,2,1)--(2,2,1)--(2,2,0)--(1,2,0)--cycle
;
\draw[line width=2pt](2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,1)--(0,0,1)--(2,0,1)--cycle;
\end{scope}
%
\begin{scope}[xshift=4cm,yshift=-44mm]
\clip(2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,2)--(0,0,2)--(2,0,2)--cycle;
\draw[line width=1pt,fill=black!5]
(0,1,1)--(1,1,1)--(1,2,1)--(0,2,1)--cycle
(1,1,1)--(2,1,1)--(2,2,1)--(1,2,1)--cycle
;
\draw[line width=1pt,fill=cyan]
(0,0,2)--(1,0,2)--(1,1,2)--(0,1,2)--cycle
(1,0,2)--(2,0,2)--(2,1,2)--(1,1,2)--cycle
;
\draw[line width=1pt,fill=black!20]
(2,0,2)--(2,0,1)--(2,1,1)--(2,1,2)--cycle
(2,0,1)--(2,0,0)--(2,1,0)--(2,1,1)--cycle
(2,1,1)--(2,1,0)--(2,2,0)--(2,2,1)--cycle
;
\draw[line width=1pt,fill=black!50]
(0,1,2)--(1,1,2)--(1,1,1)--(0,1,1)--cycle
(0,2,1)--(1,2,1)--(1,2,0)--(0,2,0)--cycle
(1,1,2)--(2,1,2)--(2,1,1)--(1,1,1)--cycle
(1,2,1)--(2,2,1)--(2,2,0)--(1,2,0)--cycle
;
\draw[line width=2pt](2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,2)--(0,0,2)--(2,0,2)--cycle;
\end{scope}
%%-----------------------------------------------------------------
\begin{scope}[xshift=15cm]
\begin{scope}[xshift=0cm,yshift=-2cm]
\draw[line width=2pt,->](.5,.5,1.5)--(.5,.5,0);
\end{scope}
\begin{scope}[xshift=0cm,yshift=0cm]
\clip(2,0,0)--(2,1,0)--(0,1,0)--(0,1,1)--(0,0,1)--(2,0,1)--cycle;
\draw[line width=1pt,fill=red]
(0,0,1)--(1,0,1)--(1,1,1)--(0,1,1)--cycle
;
\draw[line width=1pt,fill=yellow]
(1,0,1)--(2,0,1)--(2,1,1)--(1,1,1)--cycle
;
\draw[line width=1pt,fill=black!20]
(2,0,1)--(2,0,0)--(2,1,0)--(2,1,1)--cycle
;
\draw[line width=1pt,fill=black!50]
(0,1,1)--(1,1,1)--(1,1,0)--(0,1,0)--cycle
(1,1,1)--(2,1,1)--(2,1,0)--(1,1,0)--cycle
;
\draw[line width=2pt](2,0,0)--(2,1,0)--(0,1,0)--(0,1,1)--(0,0,1)--(2,0,1)--cycle;
\end{scope}
%
\begin{scope}[xshift=0cm,yshift=-44mm]
\clip(2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,2)--(0,0,2)--(1,0,2)--(1,0,1)--(2,0,1)--cycle;
\draw[line width=1pt,fill=black!5]
(0,0,2)--(1,0,2)--(1,1,2)--(0,1,2)--cycle
(0,1,1)--(1,1,1)--(1,2,1)--(0,2,1)--cycle
(1,0,1)--(2,0,1)--(2,1,1)--(1,1,1)--cycle
(1,1,0)--(2,1,0)--(2,2,0)--(1,2,0)--cycle
;
\draw[line width=1pt,fill=black!20]
(1,0,2)--(1,0,1)--(1,1,1)--(1,1,2)--cycle
(1,1,1)--(1,1,0)--(1,2,0)--(1,2,1)--cycle
(2,0,1)--(2,0,0)--(2,1,0)--(2,1,1)--cycle
;
\draw[line width=1pt,fill=black!50]
(0,1,2)--(1,1,2)--(1,1,1)--(0,1,1)--cycle
(0,2,1)--(1,2,1)--(1,2,0)--(0,2,0)--cycle
(1,1,1)--(2,1,1)--(2,1,0)--(1,1,0)--cycle
;
\draw[line width=2pt](2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,2)--(0,0,2)--(1,0,2)--(1,0,1)--(2,0,1)--cycle;
\end{scope}
%
\begin{scope}[xshift=4cm,yshift=-44mm]
\clip(2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,2)--(0,0,2)--(2,0,2)--cycle;
\draw[line width=1pt,fill=black!5]
(0,0,2)--(1,0,2)--(1,1,2)--(0,1,2)--cycle
(0,1,1)--(1,1,1)--(1,2,1)--(0,2,1)--cycle
;
\draw[line width=1pt,fill=red]
(1,1,1)--(2,1,1)--(2,2,1)--(1,2,1)--cycle
;
\draw[line width=1pt,fill=yellow]
(1,0,2)--(2,0,2)--(2,1,2)--(1,1,2)--cycle
;
\draw[line width=1pt,fill=black!20]
(2,0,2)--(2,0,1)--(2,1,1)--(2,1,2)--cycle
(2,0,1)--(2,0,0)--(2,1,0)--(2,1,1)--cycle
(2,1,1)--(2,1,0)--(2,2,0)--(2,2,1)--cycle
;
\draw[line width=1pt,fill=black!50]
(0,1,2)--(1,1,2)--(1,1,1)--(0,1,1)--cycle
(0,2,1)--(1,2,1)--(1,2,0)--(0,2,0)--cycle
(1,1,2)--(2,1,2)--(2,1,1)--(1,1,1)--cycle
(1,2,1)--(2,2,1)--(2,2,0)--(1,2,0)--cycle
;
\draw[line width=2pt](2,0,0)--(2,2,0)--(0,2,0)--(0,2,1)--(0,1,1)--(0,1,2)--(0,0,2)--(2,0,2)--cycle;
\end{scope}
\end{scope}
\end{tikzpicture}
\end{center}
\caption{}
\label{fig:pic_21-21}
\end{figure}