Multiple surfaces in 3D with different colors

Dear all,

I have a function for plot cubic elements in 3D. The shape is not clear when I use the same color for all surfaces. So, I want to make the top and bottom of each element in the same color like dark blue "[0,0.2,0.8]", while the side surfaces in a different color like light blue "[0.2,0.7,1]". How can I do that with my function? Thanks. My function is

function Plotxyz1(nely,nelx,nelz)

hx = 1; hy = 1; hz = 1;

face = [1 2 3 4; 2 6 7 3; 4 3 7 8; 1 5 8 4; 1 2 6 5; 5 6 7 8];

for k = 1:nelz

    z = (k-1)*hz;

    for i = 1:nelx

        x = (i-1)*hx;

        for j = 1:nely

            y = nely*hy - (j-1)*hy;

                vert = [x y z; x y-hx z; x+hx y-hx z; x+hx y z; x y z+hx;x y-hx z+hx; x+hx y-hx z+hx;x+hx y z+hx];

                vert(:,[2 3]) = vert(:,[3 2]); vert(:,2,:) = -vert(:,2,:);

                patch('Faces',face,'Vertices',vert,'FaceColor',[0.2,0.7,1]);

                hold on;

        end

    end

end

axis equal; axis tight; axis off; box on; view([30,30]); pause(1e-6);

end

Answer 1

[Vedant Shah]

Hi @Eja Eja,

To make the top and bottom faces of the cube a different color compared to the other faces, we can use the “patch” function twice: first for the top and bottom faces, filling them with a dark blue color, and second for the side faces, filling them with a light blue color.

The following modifications can be made to the code:

Instead of assigning all the faces of the cube to a single “face” variable:

 face = [1 2 3 4; 2 6 7 3; 4 3 7 8; 1 5 8 4; 1 2 6 5; 5 6 7 8]; 

We can create two separate variables: one for the top and bottom faces, and another for the side faces.

 top_bottom_faces = [1 2 3 4;5 6 7 8];   
 side_faces = [2 6 7 3; 4 3 7 8; 1 5 8 4; 1 2 6 5]; 

Also, we need to add two different patch statements for the respective face variables:

% Plot top and bottom faces 
patch('Faces', top_bottom_faces, 'Vertices', vert, 'FaceColor', [0, 0.2, 0.8]); 

% Plot side faces 
patch('Faces', side_faces, 'Vertices', vert, 'FaceColor', [0.2, 0.7, 1]);