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)