How to save the result of stlwrite to a specific directory chosen by the user

I am using the stlwrite to create an stl file out of a triangulted input, say for example I use f3 and v3 which are faces and verticies to create a triangulation and then convert that into stl. The stl saves in the same directory as code. I would like to have the option to ask the user of my code to chose a certain directory to save the file. how do I do that ?

TR = triangulation(f3,v3);
stlwrite(TR,'G.stl');

I am not sure I understand how uiputfile works.

Answer 1

[Stephen Cobeldick]

TR = ...
[F,P] = uiputfile('*.stl');
stlwrite(TR,fullfile(P,F))

[Oraib Ghaith AlKheetanRojas]

Dear Stephen,

for some reason it is giving me the follosing error message

Error using fileparts (line 37)

Input must be a row vector of characters or string scalar.

Error in stlwrite (line 70)

path = fileparts(filename);

However, I managed to find an answer for my question as such:

TR = triangulation(f3,v3);
[file,path,indx] = uiputfile('G.stl');
stlwrite(TR,strcat(path,'\',file));

[Rik]

You should replace the last two lines of code with the lines indicated by Stephen. That should not result in the error you describe and will avoid two issues: overwriting the path function with a variable, and failing to support operating systems that have \ as the filesep.

Answer 2

[marco mancini]

Hi,

could someone help me to solve this ERROR please?

I receive the following error using the stlwrite function:

Error using fileparts (line 37)
Input must be a row vector of characters or string scalar.
Error in stlwrite (line 70)
path = fileparts(filename);

Here my code:

X =  randi(20,200,1)
Y =  randi(20,200,1)
Z =  randi(20,200,1)

% triangulate in xy
T = delaunay(X,Y)


% tet delaunay
tri = delaunayTriangulation(X,Y,Z)
% get surface faces and nodes
[F,P] = freeBoundary(tri);
% plot with trisurf
figure
trisurf(F,P(:,1),P(:,2),P(:,3),'FaceColor','red');
 

% now save
stlwrite(tri,'mytriangulation.stl');

thanks in advance,

Marco

[Stephen Cobeldick]

@marco mancini : Please show the complete output of these commands:

which stlwrite -all
which fileparts -all

[marco mancini]

Hi @stephen,

thanks. Below the output:

E:\MATLAB\Test\3D model\Make STL of 3D array\stlwrite.m
D:\Programs\MATLAB\MATLAB 2018\toolbox\matlab\iofun\fileparts.m

I'm on matlab R2018a. I attach both file if it could help me to sport the issue,

thanks in advance,

Marco

[Walter Roberson]

Mathworks added stilwrite() as of R2018b. It appears you are using https://www.mathworks.com/matlabcentral/fileexchange/20922-stlwrite-write-ascii-or-binary-stl-files

[Walter Roberson]

You are trying ot use the syntax for the Mathworks stlwrite() with the File Exchange stlwrite function. You need to make adjustments:

h = trisurf(F,P(:,1),P(:,2),P(:,3),'FaceColor','red');
stlwrite('mytriangulation.stl',struct('faces',h.Faces, 'vertices', h.Vertices));

Note that there is a cosmetic bug in the function. It will tell you that it has written 3 faces, but it will have written them all.

[marco mancini]

Dear Walter,

thank you I confirm that is it working now!

By the way I'm wondering.... could I use the function stilwrite() of Mathworks on my r2018a version (not the "File Exchange" one) if someone share it with me?

I'm asking that, because at this time your workaround really helped me, but I guess that I won't be able to figure out a similar workaround myself everytime.

For example, I found another code, that produce an awesome 3D model that I cannot export as stl, due to the same error:

Error using fileparts (line 37)
Input must be a row vector of characters or string scalar.
Error in stlwrite (line 70)
path = fileparts(filename);

I tried to implement something similar to your workaround, but it doesn't work.... here the original code of the awesome 3D model. Could you help to customize stlwrite in order to avoid the error?

addpath('E:\MATLAB\Test\3D model\output\')
% Create a uniform hexagonal array
rows = [1:4 3:-1:1];
Radius = 1*(3);
d = 1;
pos = zeros(3,1);
count = 0;
for idx = 1:length(rows)
      y = -Radius/2 -(rows(idx)-1)*d*0.5:d: Radius/2+(rows(idx)-1)*d*0.5;
      pos(2, count+1:count+length(y)) = y;
      pos(3, count+1:count+length(y)) = sqrt(3)/2*Radius - (idx-1)*d*sind(60);
      count = count + length(y);
end
h = phased.ConformalArray('ElementPosition', pos, 'ElementNormal', ...
     zeros(2, size(pos, 2)));
h.Element = ...
      phased.IsotropicAntennaElement;
%Assign frequencies and propagation speed
F = 300000000;
PS = 300000000;
%Plot the directivity pattern
pr = plotResponse(h, F(1), PS, 'Unit','dbi', 'Format', 'Polar', ...
       'RespCut', '3D');
   set(pr, 'LineStyle', 'none');   
%Adjust the view angles
view(25, 25);
%Get the title
title = get(gca, 'title');
title_str = get(title, 'String');
%Modify the title
[Fval, ~, Fletter] = engunits(F(1));
title_str = [title_str sprintf('\n') ...
      num2str(Fval) ' ' Fletter 'Hz No Steering'];
set(title, 'String', title_str);

% THIS GENERATE THE ERROR:
 stlwrite(pr,'pr.stl','text')
 
% THIS WAS BASED ON YOUR METHOD BUT IT DOESN'T WORK:
% stlwrite('pr.stl',struct('faces',h.Faces, 'vertices', h.Vertices));

thanks,

Marco

[Walter Roberson]

You would need an R2018b or later license to use the Mathworks stlwrite

[marco mancini]

Ok thank you, I will try to upgrade and chek it again

[Walter Roberson]

Sorry the 16b was a typing mistake on my part; you need R2018b or later.

Only Mathworks would be able to authorize you to use the newer routine, and they are not going to do that. I suggest that you wait another small number of days and upgrade to R2020a when it is released which could be within the next three days.

[marco mancini]

Hi Walter, thank you.

I'm now working on r2019b, but I cannot find a way to export the following figure in STL:

The code I used for generate the figure is the following:

 
% Create a uniform hexagonal array
rows = [1:4 3:-1:1];
Radius = 1*(3);
d = 1;
pos = zeros(3,1);
count = 0;
for idx = 1:length(rows)
      y = -Radius/2 -(rows(idx)-1)*d*0.5:d: Radius/2+(rows(idx)-1)*d*0.5;
      pos(2, count+1:count+length(y)) = y;
      pos(3, count+1:count+length(y)) = sqrt(3)/2*Radius - (idx-1)*d*sind(60);
      count = count + length(y);
end
h = phased.ConformalArray('ElementPosition', pos, 'ElementNormal', ...
     zeros(2, size(pos, 2)));
h.Element = ...
      phased.IsotropicAntennaElement;
%Assign frequencies and propagation speed
F = 300000000;
PS = 300000000;
%Plot the directivity pattern
pr = plotResponse(h, F(1), PS, 'Unit','dbi', 'Format', 'Polar', ...
       'RespCut', '3D');
   set(pr, 'LineStyle', 'none');   
%Adjust the view angles
view(25, 25);
%Get the title
title = get(gca, 'title');
title_str = get(title, 'String');
%Modify the title
[Fval, ~, Fletter] = engunits(F(1));
title_str = [title_str sprintf('\n') ...
      num2str(Fval) ' ' Fletter 'Hz No Steering'];
set(title, 'String', title_str);
% THIS GENERATE THE ERROR:
 stlwrite(pr,'pr.stl','text')
 
% THIS WAS BASED ON YOUR METHOD BUT IT DOESN'T WORK:
% stlwrite('pr.stl',struct('faces',h.Faces, 'vertices', h.Vertices));

Can someone help me to export that figure please?

thanks in advance,

[Walter Roberson]

Replace from "% THIS GENERATE THE ERROR:" with

fvc = surf2patch(pr, 'triangles');
TR = triangulation(fvc.faces, fvc.vertices);
stlwrite(TR, 'pr.stl', 'text');

[marco mancini]

Dear Walter,

thank you so much! it is working ;-)

[marco mancini]

Dear All,

I've just noted that the code above was generated with an old version of the the Sensor Array Analyzer.

I'd like to share the code generated with the latest version of the SAA and check with you if it is possibile to print the STL like Walter kindly showed with the previous method.

MAIN PROBLEM: When you run the code below, the figure get printed in STL, but the result is completely different from the figure you see in your editor (this issue was not happening in older version of SAA)

Here the code:

% MATLAB Code from Sensor Array Analyzer App

% Generated by MATLAB 9.7 and Phased Array System Toolbox 4.2

% Generated on 20-Mar-2020 19:09:54

% Create a uniform rectangular array
Array = phased.URA('Size',[4 4],...
'Lattice','Rectangular','ArrayNormal','x');
Array.ElementSpacing = [0.5 0.5];
% Calculate Row taper
rwind = ones(1,4).';
% Calculate Column taper
cwind = ones(1,4).';
% Calculate taper
taper = rwind*cwind.';
Array.Taper = taper.';

% Create an isotropic antenna element
Elem = phased.IsotropicAntennaElement;
Elem.FrequencyRange = [0 300000000];
Array.Element = Elem;

% Assign Steering Angles, Frequencies and Propagation Speed
SteeringAngles = [-30;0];
Frequency = 300000000;
PropagationSpeed = 299792458;
%Assign number of Phase shift quantization bits
PhaseShiftBits = 0;
% Create Figure
% Calculate Steering Weights
Freq3D = 300000000;
% Find the weights
w = zeros(getNumElements(Array), length(Frequency));
SteerVector = phased.SteeringVector('SensorArray',Array, 'PropagationSpeed', PropagationSpeed, 'NumPhaseShifterBits', PhaseShiftBits(1));
for idx = 1:length(Frequency)
    w(:, idx) = step(SteerVector, Frequency(idx), SteeringAngles(:, idx));
end
% Plot 3d graph
format = 'polar';
% figure;
pattern(Array, Freq3D , 'PropagationSpeed', PropagationSpeed,...
 'Type','directivity', 'CoordinateSystem', format,'weights', w(:,1));

% I ADDED THIS IN ORDER TO ALLOW THE PRINT OF THE STL
Model3D = pattern(Array, Freq3D , 'PropagationSpeed', PropagationSpeed,...
 'Type','directivity', 'CoordinateSystem', format,'weights', w(:,1));

% export to STL
fvc = surf2patch(Model3D, 'triangles');
TR = triangulation(fvc.faces, fvc.vertices);
stlwrite(TR, 'STLM_apple.stl', 'text');

Thanks in advance for the contribution,