How to convert a figure of a minimal surface into an STL or OBJ file?

Hi, I've got this code for making a Schwartz D structure in MATLAB (credits to https://github.com/pttrsnv2/Minimal_Surfaces_Visualization_Code/blob/master/Minimal_Surfaces_Code_Upload_V2.m).

How could I make this into an STL or OBJ file? I need anything I could put into solidworks or fusion 360. I've tried to go through a ton of mathworks answers regarding this, but I can't seem to make stlwrite work no matter what I try.

f_sd = @(x,y,z) sin(x).*sin(y).*sin(z) + sin(x).*cos(y).*cos(z)+cos(x).*sin(y).*cos(z)...
    + cos(x).*cos(y).*sin(z);

% The limits for a 3-D plot 
x_sd_l = 0;
x_sd_u = 2*pi;
y_sd_l = 0;
y_sd_u = 2*pi;
z_sd_l = 0; 
z_sd_u = pi;

% Mesh density
MD_sd = 50; % Change as needed

% Face color
C_sd = 'red'; % Change as needed

figure
fimplicit3(f_sd, [x_sd_l x_sd_u y_sd_l y_sd_u z_sd_l z_sd_u], 'meshdensity',MD_sd,'facecolor',C_sd)
title('Schwarz D Plot')
xlabel('X')
ylabel('Y')
zlabel('Z')

Answer 1

[Supraja]

The github link you mentioned in the question is unfortunately not working. But assuming you want to convert your file into .stl or .obj file, I am attaching the documentation links below which would help you to achieve your goal.

Conversion to .stl file:

File Exchange - MATLAB Central (mathworks.com)

stlwrite - write ASCII or Binary STL files - File Exchange - MATLAB Central (mathworks.com)

surf2stl - File Exchange - MATLAB Central (mathworks.com)

stlwrite: Create STL file from triangulation - MATLAB stlwrite (mathworks.com)

Conversion to .obj file:

Save Wavefront .OBJ files (simple or colour) - File Exchange - MATLAB Central (mathworks.com)

Answer 2

[DGM]

You already have triangulated data, you just need to write it. That means that surf2stl() won't work for an fimplicit() plot. Unless you're running a version older than R2018b or have some particular special reason, you don't need FEX #20922 either. You already have an STL encoder. Just use it.

Here's an actual answer:

f_sd = @(x,y,z) sin(x).*sin(y).*sin(z) + sin(x).*cos(y).*cos(z)+cos(x).*sin(y).*cos(z)...
    + cos(x).*cos(y).*sin(z);

% The limits for a 3-D plot 
x_sd_l = 0;
x_sd_u = 2*pi;
y_sd_l = 0;
y_sd_u = 2*pi;
z_sd_l = 0; 
z_sd_u = pi;

% Mesh density
MD_sd = 50; % Change as needed

% Face color
C_sd = 'red'; % Change as needed
hfs = fimplicit3(f_sd, [x_sd_l x_sd_u y_sd_l y_sd_u z_sd_l z_sd_u], ...
    'meshdensity',MD_sd,'facecolor',C_sd);
title('Schwarz D Plot')
xlabel('X')
ylabel('Y')
zlabel('Z')

●

% get the data from the fimplicit object
F = hfs.Triangulation.ConnectivityList;
V = hfs.Triangulation.Points;

% write it to an STL
stlwrite(triangulation(F,V),'test1.stl') % R2018b+

% read it back just for show and tell
T = stlread('test1.stl');
[F V] = t2fv(T);
figure
patch('faces',F,'vertices',V,'facecolor','w','edgecolor','none');
view(3); view(-34,19); camlight; 
axis equal; grid on