how to draw a meshed geometry?

Hi

I aim to write a code which draws a geometry and then mesh it! Could you please tell me how can I edit this code so it gives out the attached figure? (please ignore the colorful pattern, I only need a meshed geometry)

% Define the vertices of the triangle
v1 = [0, 0];
v2 = [20, 0];
v3 = [30, -10];
v4 = [50, -10];
v5 = [50, -20];
v6 = [0, -20];

% Create a matrix with the vertices as rows
vertices = [v1; v2; v3; v4; v5; v6];

% Define the faces of the triangle as a 1-by-3 matrix
faces = [1, 2, 3, 4, 5, 6];

% Create a patch object with the specified vertices and faces
patch('Vertices', vertices, 'Faces', faces, 'FaceColor', 'white');

% Set the axis limits and labels
axis([0, 50, -20, 0]);
xlabel('x-axis');
ylabel('y-axis');

hold on
x1=0;
x2=50;
y1=0;
y2=-20;
npoints_x=51;
npoints_y=21;
% Create a grid of points using the meshgrid function
x_grid = linspace(x1, x2, npoints_x);
y_grid = linspace(y1, y2, npoints_y);
hold on
[X, Y] = meshgrid(x_grid, y_grid);
hold on
        mesh (X,Y,zeros(size(X)))
        

Answer 1

[KSSV]

clc; clear all ;
% Define the vertices of the triangle
v1 = [0, 0];
v2 = [20, 0];
v3 = [30, -10];
v4 = [50, -10];
v5 = [50, -20];
v6 = [0, -20];

% Create a matrix with the vertices as rows
vertices = [v1; v2; v3; v4; v5; v6; v1];

% % Define the faces of the triangle as a 1-by-3 matrix
% faces = [1, 2, 3, 4, 5, 6];
% 
% % Create a patch object with the specified vertices and faces
% patch('Vertices', vertices, 'Faces', faces, 'FaceColor', 'white');
% 
% % Set the axis limits and labels
% axis([0, 50, -20, 0]);
% xlabel('x-axis');
% ylabel('y-axis');
% 
% hold on
x1=0;
x2=50;
y1=0;
y2=-20;
npoints_x=51;
npoints_y=21;
% Create a grid of points using the meshgrid function
x_grid = linspace(x1, x2, npoints_x);
y_grid = linspace(y1, y2, npoints_y);

[X, Y] = meshgrid(x_grid, y_grid);
Z = rand(size(X)) ; 

idx = inpolygon(X,Y,vertices(:,1),vertices(:,2)) ; 
Z(~idx) = NaN ;

h = pcolor(X,Y,Z)         ;
h.EdgeColor = 'none' ;