Hello, I hope it’s okay to reply to an old topic, but I have run into a similar problem and couldn’t find the solution anywhere.
When I tried to use P3D in command line, I received the same message about gluegen-rt.dll. The sketch also worked fine using the Processing IDE.
I managed to make it work by trial and error. When I moved the sketch to the python processing folder, it did work in command line. With the file processing-py-natives-windows-amd64.jar copied in the sketch folder in addition to processing-py.jar, it finally worked.