Okay! So I bought a Rasberry Pi 4 to work on on a video project, and I couldn’t find an up-to-date guide on how to get Processing.py to run in headless mode on the Rasberry Pi. So here we are!
Why would anyone want to do this? Well, I have ideas on generating real-time video, and I’m too lazy to do maths to do it properly, so why not run a huge bloated java application to do it for me? Yeah!
Okay, so I assume you have a Rasberry Pi 4. This guide actually works even thought it says it doesn’t. That’ll get us started.
Here’s a list of things we need to do:
- Install a fake x server to pretend we have a window
- Install the right version of java we need
- Install Processing and Processing.py
We’re going to install xvfb which stands for X video frame buffer. Processing needs a window to output, but we don’t have a window, so we can create a fake one.
sudo apt install xvfb libxrender1 libxtst6 libxi6
Now we’ve got that, let’s make a file called /home/pi/bin/start_xvfb:
sudo Xvfb :1 -screen 0 1024x768x24 </dev/null &
export DISPLAY=":1"
Make it executable:
pi@raspberrypi:~/bin $ chmod +x start_xvfb
Then change /etc/rc.local to run that script on startup:
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
printf "My IP address is %s\n" "$_IP"
fi
/home/pi/bin/start_xvfb
exit 0
Okay okay okay, we’ve got our bloody window starting up each time. Noice.
Here’s where things change from the instuctions above though, DO NOT install java through the command line. We need to download the specific java version that processing.py uses.
We need version 8u202, specifically this version: jdk-8u202-linux-arm32-vfp-hflt.tar.gz
I needed to make an account just to download it, fuck you Oracle. 🖕
I downloaded it on Windows, yes my work computer is Windows, and powershell is not terrible. Sometimes. Copy to the pi:
> scp jdk-8u202-linux-arm32-vfp-hflt.tar.gz pi@raspberrypi.local:/home/pi
… and on the Pi
pi@raspberrypi:~ $ tar -xvzf jdk-8u202-linux-arm32-vfp-hflt.tar.gz
pi@raspberrypi:~ $ sudo cp -r jdk1.8.0_202/ /usr/local/
Then add this line to you ~/.bashrc file:
export PATH=/usr/local/jdk1.8.0_202/bin:$PATH
Adding it to the front of PATH means it’ll take precedence over the 50 other java versions you have installed. Let’s test that shit works:
pi@raspberrypi:~ $ source .bashrc
pi@raspberrypi:~ $ java -version
java version "1.8.0_202"
Java(TM) SE Runtime Environment (build 1.8.0_202-b08)
Java HotSpot(TM) Client VM (build 25.202-b08, mixed mode)
Wooo!
Okay okay okay, now where were we, oh yeah, getting the bloody thing to work. So far we have the fake window manager running, and the correct version of java installed.
Next we need to download processing and processing.py. To get processing, their website tells us how to install it.
pi@raspberrypi:~ $ curl https://processing.org/download/install-arm.sh | sudo sh
To get processing.py, their website has a command line page which is quite helpful.
The thing we need to get is the Linux 32 bit standalone verion.
pi@raspberrypi:~ $ wget http://py.processing.org/processing.py-linux32.tgz
pi@raspberrypi:~ $ tar -xzvf processing.py-linux32.tgz
The file we want is the file processing-py.jar located in the directory processing.py/processing.py-<version>-linux32/
To test it, let’s my a dumb script that just prints "It's running", and draws an image that you can never see…
def setup():
size(150, 84)
print("It's running!")
x = 0
y = 0
def draw():
global x,y
background(255)
fill(0)
ellipse(x, y, 20, 20)
x += 1
x %= width
y += 1
y %= height
pi@raspberrypi:~/processing.py/processing.py-3017-linux32 $ java -jar processing-py.jar test_file.py
It's running!
🎉🎉🎉
Now, there’s no real point to generating real-time video if we can’t pass variables to it. Not sure how to do that… Did I just waste all that time? Lol. That’s for the next installment!