Getting Started With JRubyArt on RaspberryPI

Thanks to Sam Aarons SonicPI, you may already have been introduced to ruby, now there is an opportunity to extend your creative skills in ruby. JRubyArt can be used to create art, animations, videos and much more. Also since it is based on the latest Processing you can access a vast range of processing libraries that make difficult things easier (some available as ruby gems).

Installing Processing on the RaspberryPI

By far the easiest and most reliable way to get started is to use the processing.org custom raspbian image. You should download the processing raspbian image here and write the image to a spare SD card, see pi.processing website. If you want to use a usbstick / usbdrive you need to tell your raspberrypi to do a usb boot (this is one time and and irreversible step so not for noobs), see here, there are plenty of tools for writing images to usb drives (eg mintstick on mint linux).

Connecting WiFi

It is assumed that you will use wifi (instead of ethernet cable) to connect to the internet, so once you have booted the processing raspbian image use raspi-config to set your wifi region and enter your wifi connection credentials. Once you have connected it is worth updating raspi-config, although that will mean re-entering your wifi connections, but this time you will be able to use the gui. Clicking on the wifi connection widget you will get a choice of connections choose yours and re-enter credentials. You can set a unique network hostname from the RaspberryPI configuration gui.

Preparing to install gems

It is normal to install gems to a local folder, but you need to define the GEM_HOME to do so, what I usually do is to modify ~/.profile to modify the local bash environment see my ~/.profile:-

# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022

# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
	. "$HOME/.bashrc"
    fi
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

export GEM_HOME="/home/pi/.gem/ruby/2.3.0"
export GEM_PATH="/home/pi/.gem/ruby/2.3.0"
export PATH="${PATH}:${GEM_PATH}/bin"

Note this profile is not immediately available to your shell but you could do source ~/.profile to make it so or re-boot. NB: be very careful here an invalid .profile may prevent you from logging into raspberrypi.

It is also worth creating a ~/.gemrc if only to avoid downloading unnecessary gem documentation (wastes time, and takes up space)

---
  gem:
    -no-document

You should then do a gem system update:-

sudo gem system --update

Now you are ready to install JRubyArt

Installing JRubyArt

gem install jruby_art
k9 --install # should create config.yml for you since JRubyArt-1.5.0
# also installs JRuby-Complete and examples in ~/k9_samples
k9 --check

The k9 –check should pass with PROCESSING_ROOT: "/usr/local/lib/processing-3.4" and JRUBY: false

With this configuration JRubyArt knows where to locate processing jars, and that we wish to JRubyComplete, rather than an installed JRuby.

Now you are good to go cd k9_samples and rake to start a sequential demo of some sketches (NB: some won’t work on raspberrypi), closing one sketch starts another.

Creating your own sketches

It makes sense to create a directory in which to create your sketches, the you can use k9 --create tool to make your own

mkdir my_sketches
cd my_sketches
k9 --create my_sketch 300 300

This creates a blank sketch my_sketch.rb which is also a valid sketch (can be run) but is not too interesting. I suggest using vim as your JRubyArt editor, but you could use geany. Actually the simplest sketch you could create with JRubyArt is just one line (similar to SonicPI and vanilla processing) here is an example:-

background 200, 0, 0

Have fun exploring!!!

Some gems to install

rubocop …static code analysis

wordcram

toxiclibs

geomerative