\documentclass[crop,tikz]{standalone}
\input{common-headers}
\input{sigles}

\begin{document}
\newcounter{bacteria}

\tikzset{coord/.style={fill,inner sep=0.5mm, circle, black}}

\def \mybact#1#2#3#4#5{
    \stepcounter{bacteria};
    \coordinate (p#5) at #1;                      % position vector
    \coordinate (d#5) at #2;                      % direction vector
    \coordinate (n#5)  at ($ (0,0)!1! 90:(d#5) $);  % orthogonal vector
    \coordinate (ft#5) at ($ (p#5) + {  #3+#4 }*(d#5) + #4*(n#5) $);
    \coordinate (fb#5) at ($ (p#5) + {  #3+#4 }*(d#5) - #4*(n#5) $);
    \coordinate (bt#5) at ($ (p#5) + {-(#3+#4)}*(d#5) + #4*(n#5) $);
    \coordinate (bb#5) at ($ (p#5) + {-(#3+#4)}*(d#5) - #4*(n#5) $);
    \draw[black,rounded corners=#4cm]
        (bt#5) -- (bb#5) -- (fb#5) -- (ft#5) -- cycle;
%
    \coordinate (f#5) at ($ (p#5) + #3*(d#5) $);
    \coordinate (b#5) at ($ (p#5) - #3*(d#5) $);
%    \node[coord,label=$p_{#5}$] at (p#5) {};
%
    \coordinate (ff#5) at ($ (p#5) + {2*#3}*(d#5) $);
    \coordinate (bb#5) at ($ (p#5) - {2*#3}*(d#5) $);
    \draw[very thin] (ff#5) -- (bb#5);
}
% Usage:
% \mybact {|position vector|} {|direction vector|} {width}{height}{name};

\begin{tikzpicture}
    \draw [help lines] (0,0) grid (6,2);
    \mybact{(3,1)}{(1,0)}{2}{1}{\arabic{bacteria}};
    \node[coord,label=above:$f_\arabic{bacteria}$] at (f1) {};
    \node[coord,label=below:$b_\arabic{bacteria}$] at (b1) {};
\end{tikzpicture}

\newcommand{\bactsPosAndAngle}{%
  \coordinate (PosA) at ( 0  ,3);
  \coordinate (AngA) at ($ (0,0) !1! 28:(1,0) $);
  \coordinate (PosB) at (-0.7,0);
  \coordinate (AngB) at ($ (0,0) !1! -3:(1,0) $);
  \mybact{(PosA)}{(AngA)}{2}{1}{1};
  \mybact{(PosB)}{(AngB)}{2}{1}{2};
}

\begin{tikzpicture}
  \bactsPosAndAngle
  
  \node[coord,label=above:$f_1$] at (f1) {};
  \node[coord,label=below:$f_2$] at (f2) {};
  \node[coord,label=below:$b_2$] at (b2) {};
    
  \coordinate (po) at ($ (b1)!(f2)!(f1) $);
  \draw[dashed] (f2) -- (po);
  % \draw[rotate=-9] (po) rectangle ++(1mm,-1mm);
  \node[coord,red,label=above:$\perp_{f_2}$] at (po) {};
  
  \coordinate (pp) at ($ (b2)!(b1)!(f2) $);
  \draw[dashed,thick,red] (b1) -- (pp);
  \node[coord,red,label=below:$\perp_{b_1}$] at (pp) {};
  
  \coordinate (pq) at ($ (b2)!(f1)!(f2) $);
  \draw[dashed] (f1) -- (pq);
  \node[coord,label=$b_1$] at (b1) {};
  \node[coord,red,label=right:$\perp_{f_1}$] at (pq) {};
  
  \coordinate (pr) at ($ (b1)!(b2)!(f1) $);
  \draw[dashed] (b2) -- (pr);
  \node[coord,red,label=above:$\perp_{f_2}$] at (pr) {};
\end{tikzpicture}

\begin{tikzpicture}
  \bactsPosAndAngle
  
  \coordinate (col) at ($(b1)!.5!(pp)$);
  
  \node[coord] at (f1) {};
  \node[coord] at (f2) {};
  \node[coord] at (b2) {};
  \node[coord] at (b1) {};

  \node[coord,red] at ($ (b2)!(b1)!(f2) $) {};
  %\node[coord,label=left:$P$] at (col) {};
  \node[coord,label=left:$p_1$] at (p1) {};
  \node[coord,label=below:$p_2$] at (p2) {};
    
  \draw[-Stealth] (p1) to node[auto] {$\orr{r_1}$} (col);
  \draw[-Stealth] (p2) to node[auto,swap] {$\orr{r_2}$} (col);
  \draw[-Stealth] (col) to node[auto] {$\orr{n}$} ($(col)!.4!(b1)$);
  
\end{tikzpicture}

\end{document}