Unstructured mesh for a domain in TikZ

unstructuredmesh.tex

\newcommand{\meshnodes}{
  \coordinate (a) at (4.53,2.86) ;
  \coordinate (b) at (2.91,3.55) ;
  \coordinate (c) at (2.25,1.8) ;
  \coordinate (d) at (-0.3,3.25) ;
  \coordinate (e) at (1.31,4.17) ;
  \coordinate (f) at (1.19,0.43) ;
  \coordinate (g) at (2.77,0.7) ;
  \coordinate (h) at (3.96,3.54) ;
  \coordinate (i) at (0.05,1.17) ;
  \coordinate (j) at (2,3.1) ;
  \coordinate (k) at (3,4.7) ;
  \coordinate (m) at (3.93,1.65) ;
  \coordinate (n) at (1.78,0.76) ;
  \coordinate (o) at (0.40,4.4) ;
  \coordinate (p) at (0.8,2.5) ;
  \coordinate (q) at (4.72,1.32) ;
  \coordinate (r) at (3.02,2.27) ;
  \coordinate (s) at (0.98,1.83) ;
  \coordinate (t) at (-0.3,1.8) ;
}


\newcommand{\withmeshtris}[1]{
  #1 cgn #1 snf #1 jsc #1 pjs
  #1 pts #1 sif #1 sit #1 dtp
  #1 odp #1 epj #1 jcb #1 oep
  #1 rcg #1 crb #1 kbh #1 rah
  #1 ejb #1 rgm #1 ram #1 qam
  #1 ekb #1 gqm #1 scn #1 bhr
}

\newcommand{\drawtriangle}[3]
  {\draw (#1) -- (#2) -- (#3) -- (#1);}
\newcommand{\meshtris}{
  \withmeshtris\drawtriangle
}
\def\drawnodenames{
  \foreach \i in {a,b,c,d,e,f,g,h,i,j,k,m,n,o,p,q,r,s,t}
    \node at (\i) {\i};
}

usage.tex

\input{media/unstructuredmesh.tex}
\begin{center}
\begin{tikzpicture}
  \meshnodes
  \meshtris
  %\drawnodenames
  \node [left=1cm of d] {$\Omega$};
  \draw [fill=blue!30] (c) -- (n) -- (g) ;
  \node [below=5mm of g,xshift=-5mm] (ellabel) {$\D_k$};
  \draw [thick,->,shorten >=5mm] (ellabel) -- (c) ;
\end{tikzpicture}