How to slice a 3D structure into a X-Y planar?

I get the error

''Error using slice (line 85)

V must be a 3-D array.

Error in HEX_hybridization (line 104)

slice(X,Y,Z,TO,xslice,yslice,zslice)''

How can I make TO=V a 3D array?

clc
clear
close all

% Define the space boundary of the TPMS in x,y,z, in terms of number of unit cells
Lx = 3; 
Ly = 3; 
Lz = 9; 

% Define dimensions in centimeters
unitCellLength_mm = 10; % Length of the unit cell in millimeters
wallThickness_um = 100; % Wall thickness in micrometers

% Define mesh resolution (number of grid points per unit cell)
Nx = 5; 
Ny = 5; 
Nz = 5; 

% Generate meshgrid for the entire structure
x = linspace(0, 3, Nx*3);
y = linspace(0, 3, Ny*3);
z = linspace(0, 9, Nz*9);
[X, Y, Z] = meshgrid(x, y, z);

% Define  equations
EQ_gy = cos(2*pi*X).*sin(2*pi*Y) + cos(2*pi*Y).*sin(2*pi*Z) + cos(2*pi*Z).*sin(2*pi*X); %gyroid TPMS 
sig = 1./(1+exp(4*x)); %sigmoid function
C1 = 1-sig;
C2 = 1-C1;
EQ_hyb = (sig.*EQ_pr+C1.*EQ_gy+C2.*EQ_dm); %PGD,

% Volume fraction and porosity
volumeFraction = 0.5; 
porosity = 1 - volumeFraction;

% Threshold to obtain the desired volume fraction
threshold = (max(EQ_hyb(:)) - min(EQ_hyb(:))) * volumeFraction + min(EQ_hyb(:)); 

% Generate the TPMS structure
structure = EQ_hyb <= threshold;

% Isosurface and isocap
[F1,V1] = isosurface(X,Y,Z,structure,0.5);
[F2,V2] = isocaps(X,Y,Z,structure,0.5);

%Combines isosurface and isocaps into one
F3 = [F1;F2+length(V1(:,1))];
V3 = [V1;V2];
TO = triangulation(F3,V3(:,1),V3(:,2),V3(:,3));
trisurf(TO,'FaceColor','c','FaceAlpha',1,'EdgeAlpha',1,'EdgeColor','none');

%Slice the topology to view the grading/hybridization at unit cell level
xslice = [0.5,1.5,2.5];   
yslice = [];
zslice = 0;
slice(X,Y,Z,TO,xslice,yslice,zslice)