Enable launching MATLAB desktop from the extern launcher

[nilsjor]

Description
This will add features as described in #6362 (comment)

Related Issues
This pull-request fixes issue #6362

Tasks
Add the list of tasks of this PR.

• Add the --interactive option to the webots-controller which will launch MATLAB in interactive (debug) mode.
• Remove references to deprecated commands in example files.
• Change the documentation to reflect the new workflow.

Documentation
The following pages have been changed:

• https://cyberbotics.com/doc/guide/matlab#using-the-matlab-desktop
• https://cyberbotics.com/doc/guide/running-extern-robot-controllers

[omichel]

It looks very good to me. Remain to address the documentation.

[nilsjor]

@matl-hsk could you please help testing on macOS?

1. Open the "mir100" world in webots.
2. Change the "controller" field of Mir100 (the white AGV) to <extern>.
3. Run the Webots simulation. Nothing should happen until an extern controller has connected.
4. In a new Terminal window, call the following:

webots-controller --interactive ~/webots/projects/robots/mir/mir100/controllers/keyboard_matlab/keyboard_matlab.m

5. Wait until MATLAB opens. Click "Continue" in the debugging toolstrip.
6. The simulation should start. Click on the Mir100 robot. Try to drive it with the arrow keys of your keyboard.

[matl-hsk]

sorry for the delay.

I've tested your branch but it does not open Matlab, neither with the interactive option nor without. I can however

• start Matlab and run the launcher manually (similar to how you described it in the issue)
• start Matlab in batch mode from webots

[nilsjor]

sorry for the delay.

I've tested your branch but it does not open Matlab, neither with the interactive option nor without. I can however

* start Matlab and run the launcher manually (similar to how you described it in the issue)

* start Matlab in batch mode from webots

Can you provide the output from the terminal?

Have you tried using webots-controller for any other controller, python, etc.?

[matl-hsk]

unfortunately it does not give any hint on the error. I looked at the code but could not find an issue quickly.

The started controller targets a local instance (ipc protocol) of Webots with port number 1234.
Targeting the only robot waiting for an extern controller.
Running MATLAB in interactive mode...

[nilsjor]

Note that it takes a while to start Matlab. The launcher is written to wait until the instance closes. After calling the externlauncher, is control ever returned to you, or dou need to Ctrl-C? What do you get if you run without the interactive flag? Have you tried providing the matlab path, perhaps it cannot find it? Mvh

…

________________________________ From: matl-hsk ***@***.***> Sent: Friday, September 8, 2023 8:49:49 AM To: cyberbotics/webots ***@***.***> Cc: nilsjor ***@***.***>; Assign ***@***.***> Subject: Re: [cyberbotics/webots] Enable launching MATLAB desktop from the extern launcher (PR #6366) unfortunately it does not give any hint on the error. I looked at the code but could not find an issue quickly. The started controller targets a local instance (ipc protocol) of Webots with port number 1234. Targeting the only robot waiting for an extern controller. Running MATLAB in interactive mode... — Reply to this email directly, view it on GitHub<#6366 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AKAL6TW2XCPYVDCZJP4TLJ3XZK5Y3ANCNFSM6AAAAAA4BVLQOE>. You are receiving this because you were assigned.Message ID: ***@***.***>

[matl-hsk]

Have you tried providing the matlab path, perhaps it cannot find it?

This was it! From webots itself it can find Matlab and from the terminal I can start it as well.

Suggestion: Instead of "Running Matlab ..." it should rather print an error when it cannot find Matlab.

Two more issues

• The "-wait" option for Matlab is only available for windows but not on Linux or Mac.
• For the webots command a small script to start it is created in the webots home folder but not for the webots-controller. For the latter one has to dig into the folder "Contents/MacOS" to find it. I would rather make this consistent. Or is this on purpose?

[nilsjor]

Suggestion: Instead of "Running Matlab ..." it should rather print an error when it cannot find Matlab.

This is a great observation! But the solution lies outside the scope for this PR. As you saw, this bug appears also for non-interactive use... If you you could, please open another Issue; "No error generated when webots-controller is unable to find executable" or similar ;)

For the future, I believe the underlying reason has to do with the configuration of your MSYS. You could check the PATH variables, it is likely that you are missing something.

The "-wait" option for Matlab is only available for windows but not on Linux or Mac.

That's interesting. Perhaps it is already the default behaviour on unix that the MATLAB window is blocking... Could you test that for me? Just run matlab in a terminal and check if control is returned at any point.

For the webots command a small script to start it is created in the webots home folder but not for the webots-controller. For the latter one has to dig into the folder "Contents/MacOS" to find it. I would rather make this consistent. Or is this on purpose?

This is also a separate Issue, feel free to report it if you want. It could also have to do with your MSYS installation, it would have to be reproduced by someone else.

Finally—regarding the features of this PR—did you get the interactive debugging to work? Were you able to reproduce these 6 steps?

1. Open the "mir100" world in webots.
2. Change the "controller" field of Mir100 (the white AGV) to <extern>.
3. Run the Webots simulation. Nothing should happen until an extern controller has connected.
4. In a new Terminal window, call the following:

webots-controller --interactive ~/webots/projects/robots/mir/mir100/controllers/keyboard_matlab/keyboard_matlab.m

5. Wait until MATLAB opens. Click "Continue" in the debugging toolstrip.
6. The simulation should start. Click on the Mir100 robot. Try to drive it with the arrow keys of your keyboard.

[matl-hsk]

On topic:

• Yes, Matlab blocks the terminal until it is closed.
• It works all as intended when I specify the Matlab path.

Off topic:

• I understand that you want to prevent feature creep in this PR - okay with me to not fix the other issues.
• Regarding the path: Matlab is in the user path (usr/local/bin) but apparently the app is started as another user or does not use the path variable. I am mostly a Linux user and don't know how this is handled on Mac.

[nilsjor]

• Yes, Matlab blocks the terminal until it is closed.

• It works all as intended when I specify the Matlab path.

Great, thanks!

As a last touch, I moved the printout so it will only appear if a valid installation is found. I also removed -wait from non-windows versions.

Out of curiosity, I had a look at why it does not warn, and I found this

webots/src/controller/launcher/webots_controller.c

Lines 187 to 192 in 58d1b50

	#ifndef __APPLE__
	if (directory == NULL) {
	fprintf(stderr, "No installation of MATLAB available.\n");
	return false;
	}
	#endif

It seems that the error is suppressed only on macOS. I could not tell you why... Please include this in your Issue, if you open one.

[nilsjor]

Hello again. What else is needed to go ahead with this? I see it is still pending reviewers.
@ygoumaz pehaps you can have a look, since I know you are familiar with the webots-controller launcher?

I have left some explanations on the important files:

• src/controller/launcher/webots_controller.c
• lib/controller/matlab/launcher.m

Other than that, it's just the documentation and removed references to desktop in some examples (thanks matl-hsk!)

[omichel]

I did a first review a while ago, but my requests for change were not yet taken into account or answered.

[matl-hsk]

Sorry for the late reply - I was too busy with other stuff. Thanks for the reminder.

Code looks good to me but that does not work as intended:

As a last touch, I moved the printout so it will only appear if a valid installation is found. I also removed -wait from non-windows versions.

I just tried without specifying the Matlab path and it still prints "starting matlab" although it cannot find it. Until a proper solution is available, I'd suggest to change the phrase to give a hint that if nothing happens one should try to specify the path to matlab. (Hope that fits into the PR.)

[nilsjor]

I just tried without specifying the Matlab path and it still prints "starting matlab" although it cannot find it. Until a proper solution is available, I'd suggest to change the phrase to give a hint that if nothing happens one should try to specify the path to matlab. (Hope that fits into the PR.)

Thanks again for the feedback! I am still of the opinion that this is outside the scope of this PR. It seems to me that the problem lies somewhere in the function get_matlab_path(), which is unchanged in this PR.

To summarize, could you confirm the following:

1. Running webots-controller without interactive and without matlab-path: MATLAB never opens.
2. Running webots-controller with interactive and without matlab-path:
   "Running MATLAB in interactive mode..." ...but MATLAB never opens.
3. Running webots-controller without interactive and with correct matlab-path: MATLAB runs in batch mode.
4. Running webots-controller with interactive and with correct matlab-path:
   "Running MATLAB in interactive mode..." and then MATLAB opens in interactive mode.

It appears that the launcher skips the following lines, even though the function should return false if there is not installation in the default path:

webots/src/controller/launcher/webots_controller.c

Lines 899 to 901 in 58d1b50

	// If no MATLAB installation path was given in command line, check in default installation folder
	if (!matlab_path && !get_matlab_path())
	return -1;

The expected behavior here is that the launcher exits and you get:

webots/src/controller/launcher/webots_controller.c

Lines 207 to 208 in 58d1b50

	fprintf(stderr, "No installation of MATLAB available.\n");
	return false;

Could you please create a new issue, call it "macOS: No error generated when webots-controller cannot find executable".

There, please list the steps needed to reproduce it on the webots R2023b release (i.e., without this PR), including the path to your installed version of MATLAB, macOS, etc. Also describe if the launcher exits or if you need to Ctrl+C to return control.

Thanks!

[matl-hsk]

1. Running webots-controller without interactive and without matlab-path: MATLAB never opens.
2. Running webots-controller with interactive and without matlab-path:
   "Running MATLAB in interactive mode..." ...but MATLAB never opens.
3. Running webots-controller without interactive and with correct matlab-path: MATLAB runs in batch mode.
4. Running webots-controller with interactive and with correct matlab-path:
   "Running MATLAB in interactive mode..." and then MATLAB opens in interactive mode.
   all correct

[matl-hsk]

Could you please create a new issue, call it "macOS: No error generated when webots-controller cannot find executable".

Done and assigned you, @nilsjor.

[omichel]

Thank you both.