Исходники иллюстрации

\documentclass[tikz]{standalone}\input{pre.tex}\begin{document}\begin{tikzpicture}

    \draw[line width=2pt] (-0.1,-1,0.2) -- ++(0,1,0);

    \begin{scope}[canvas is yz plane at x=-0.2]
        \draw (0,0) rectangle (3,3);
    \end{scope} 
    \begin{scope}[canvas is yz plane at x=0]
        \draw[fill=white] (0,0) rectangle (3,3);
        \draw[transform shape, fill=magenta] (1.5,2) circle (2pt);
    \end{scope}

    \begin{scope}[canvas is xz plane at y=3]
        \draw[fill=white] (0,0) rectangle (-.2,3);
        \lineann[2]{90}{3}{$a$}
    \end{scope} 

    \begin{scope}[canvas is xz plane at y=1.5]
        \lineann[-1.2]{90}{2}{$\frac{2}{3}a$}
        \draw[force,->] (3,2) -- ++ (-1,0) node [left] {$\vec{v}$};
    \end{scope} 

    \begin{scope}[canvas is xy plane at z=3]
        \draw[fill=white] (0,0) rectangle (-.2,3);
        \lineann[2]{90}{3}{$a$}
    \end{scope}     
    \draw[line width=2pt] (-0.1,3,0.2) -- ++(0,1,0);
    \draw (0,1.5,2) node[above] {$A$};
    \draw[fill=magenta] (3,1.5,2) circle (4pt) node[above, yshift=0.5em] {$m$};
    % \fill[magenta] (0,0) circle (2pt) node[above, yshift=0.5em] {$O$};

    % \draw (0,0)++(-0.2,0.2) rectangle ++ (0.4,-3);
    % \lineann[2]{90}{-2.8}{$L, m$}

    % \draw (0,0) -- ++(-40:2) coordinate (g);

    % \fill[magenta] (g) circle (5pt) node [right, xshift=0.5em] {$m$};
    % \lineann[2]{-40}{2}{$l$}

    % \draw (2,-2) node[blue] {$\bigotimes$} node[right, xshift=.5em] {$\vec{N}$};

\end{tikzpicture}\end{document}