Creating an Object with alphaShape function

Hi everyone!

I'm working on a foundation engineering project. Previously, I defined a rock with using alphaShape function with this code;

% My Rock
x = randn(1000,1);
y = randn(1000,1);
z = randn(1000,1);
% Alpha Shape and plot
as = alphaShape(x,y,z,4);
plot(as,'FaceColor',[218 136 86]./255,'EdgeAlpha',0)
title('My Rock')
lighting gouraud
light('Position',[2 -4 2],'Style','local')

And, now I needed to define a geogrid, like in the picture with using alphaShape function.

Thanks for help!