FEM polygon 2D

using Makie

 coordinates = [
     0.0 0.0;
     0.5 0.0;
     1.0 0.0;
     0.0 0.5;
     0.5 0.5;
     1.0 0.5;
     0.0 1.0;
     0.5 1.0;
     1.0 1.0;
 ]
 connectivity = [
     1 2 5;
     1 4 5;
     2 3 6;
     2 5 6;
     4 5 8;
     4 7 8;
     5 6 9;
     5 8 9;
 ]
 color = [0.0, 0.0, 0.0, 0.0, -0.375, 0.0, 0.0, 0.0, 0.0]
 poly(coordinates, connectivity, color = color, strokecolor = (:black, 0.6), strokewidth = 4)