Mathematica Link and NetLogo 3D

[evolvingtech]

Mathematica Link (for Version 12 of Mathematica) enables the launching, manipulating and running of regular NetLogo 6.2.X 2D models, but it does not seem to provide a mechanism for launching NetLogo 3D apps and their 3D models.

Possibly, there is some way to have NetLogo 3D 6.2.1.app (or NetLogo 3D 6.2.1.exe on Windows) launched when executing NLStart. If it is supported and documented somewhere, apologies for having missed it.

[LaCuneta]

I don't think it's documented, but it should be possible to use NetLogo 3D with Mathematica-Link. My apologies as again I'm not able to test the below advice. I'll update this issue once I do, but I wanted to send the info along in case you wanted to give it a try.

NetLogo has a set of Java properties that affect its behavior, and one of those is org.nlogo.is3d. If you start NetLogo up with that set to true then it'll launch in 3D mode. For our purposes in Mathematica-Link, the way you set a Java property at startup is using the CommandLine argument:

NLStart["/Applications/NetLogo 6.2.1", CommandLine -> "/Library/Java/JavaVirtualMachines/liberica-jdk-17-full.jdk/Contents/Home/bin/java -Dorg.nlogo.is3d=true"];

One thing I'm concerned with is that NetLogo 3D requires a set of system libraries to run the 3D display. Those libraries are in app/natives/ under the NetLogo directory on Windows. If NetLogo cannot load them it will display an error indicating that on startup. If you encounter this issue the ways around it would be 1) to change the working directory to the NetLogo app folder (I'm not sure how to do this from Mathematica and JLink), or 2) you could copy the whole natives folder to the working directory Mathematica is using (I think this would be easier - you just need to find out what hte working folder is).

I hope that helps, and again I'll update this as soon as I'm able to test.

[LaCuneta]

I was finally able to test this out. The NLSetup[] command I provided did work, but as I suspected the native 3D libraries NetLogo needs were not found. I tried getting Mathematica and Java to use the NetLogo 3D app as the working directory, but ran into issues. It turned out to be easier to copy the native libraries over to the default working directory for Mathematica and Java. Short steps for that:

• Open Mathematica with a new/empty notebook and run Directory[]; to get the default working directory.
• In Windows, copy the app\natives folder from the NetLogo installation location over to the directory found above. If your default working directory was C:\Users\myuser then you'd copy app\natives to C:\Users\myuser\natives. In macOS you'll need to copy the NetLogo 3D 6.2.1.app/Contents/Java/natives folder.
• Run with the custom CommandLine argument with the is3d setting:
  NLStart["/Applications/NetLogo 6.2.1", CommandLine -> "/Library/Java/JavaVirtualMachines/jdk1.8.0_202.jdk/Contents/Home/bin/java -Dorg.nlogo.is3d=true"];

Once that opens successfully, you should be able to open models and interact with them as normal:

<< NetLogo`
NLStart["/Applications/NetLogo 6.2.1", CommandLine -> "/Library/Java/JavaVirtualMachines/jdk1.8.0_202.jdk/Contents/Home/bin/java -Dorg.nlogo.is3d=true"];
NLLoadModel["/Applications/NetLogo 6.2.1/models/3D/Sample Models/Flocking 3D.nlogo3d"];
NLCommand["setup"];
NLCommand["repeat 100 [go]"];

I did test this with Java 17 (which I think you'd been trying to use previously based on the other issue) and it did not work; there was an exception generated on load. Switching to a Java 8 runtime got things working.