NB: important information for Mac Users

Sam Pottinger has created a version of vanilla processing that will run with jdk11, I would seriously recommend macOS users to use this for JRubyArt. It may require compiling and careful setting of PROCESSING_ROOT, otherwise try propane instead.

Getting Started With JRubyArt (stolen from Ben Lewis)

For other languages see wiki Español, more contributions welcome

If you love to code because it is a creative process, then you should give JRubyArt a try because it can be used to create music, art, animations, videos and much more. Also since it is based on the latest Processing you can access a vast range of libraries to make the difficult things easier.

What Is Processing?

Processing is a simple language, based on Java, that you can use to create digital graphics. It’s easy to learn, fun to use, and has an amazing online community comprised of programmers, visual artists, musicians, and interdisciplinary artists of all kinds.

Processing was built by Benjamin Fry and Casey Reas ☯, two protegés of interdisciplinary digital art guru John Maeda at the MIT Media Lab.

Since the project began in 2001, it’s been helping teach people to program in a visual art context using a simplified version of Java. It comes packaged as an IDE that can be downloaded and used to create and save digital art “sketches”.

In 2009, Jeremy Ashkenas (aka jashkenas, creator of Backbone.JS, Underscore.JS, and Coffeescript), published the original ruby-processing gem. It wraps Processing in a shim that makes it even easier to get started if you know Ruby. It has been since updated to use processing-2.2.1 by Martin Prout (final version using jruby-1.7.27 corresponding to ruby-1.9.3 syntax), NB: no more releases are expected, and ruby-processing is not compatible with processing-3.0+.

In 2015, Martin Prout (aka monkstone) published the JRubyArt gem, loosely based on the original ruby-processing, but updated to use processing-3.5.3 and jruby-9.2+ (ruby2.4+ syntax)

Why JRubyArt?

Since Processing already comes wrapped in an easy-to-use package, you may ask: “why should I bother with JRubyArt?”

The answer: if you know how to write Ruby, you can use Processing as a visual presentation layer of a much more complex program. Games, interactive art exhibits, innovative music projects, anything you can imagine; it’s all at your fingertips.

Additionally, you don’t have to declare types, voids, or understand the differences between floats and ints to get started, as you do in pure Processing.

Although there are some drawbacks to using the Ruby version Processing (slower start up time, and sometimes performance), having Ruby’s API available to translate your ideas into sketches more than makes up for them.

Why was ruby-processing not updated to use processing-3.0+? The major changes between processing-2.2.1 and processing-3.0 are not backward compatible. Furthermore since JRubyArt was designed to use jruby- from the outset, it makes use of the more literate ruby-2.2 syntax (although the original ruby-processing might run with jruby-9.2+, the examples and the ruby-processing library are all based on ruby-1.9.3 syntax).


Setting JRubyArt for the first time, can seem a bit involved (especially if you are addicted to rvm or rbenv). The JRubyArt gem relies on jruby-9.2+ and adoptopenjdk11.

Install homebrew, wget (using homebrew), java (11.0_3+).

In case you have issues, it has been reported to be useful to set the JAVA_HOME and to add the path to java to your PATH

Finishing up

Fire up processing, and use the processing ide to install the sound and video libraries as these are no longer included in the download (but you will surely want them):-

Sketch/Import Library/Add Library/Video ide menu


brew cask install adoptopenjdk11


It is possible to run JRubyArt without a system install of jruby. But you may not be able to use gems in your sketches without a jruby executable. Mac users it seems are wedded to rbenv or rvm, and should use what they generally use to install vanilla ruby, to install jruby-9.2+. For the independently minded, there is a bitnami installer for jruby-9.2+ or you may prefer a homebrew install for jruby-9.2+. I haven’t tried either as a linux user.



JRubyArt needs to know where you’ve installed processing, where your processing sketchbook lives (for the video and audio libraries etc), and whether you’ve done a system/user install of jruby.

Config file is config.yml in the ~/.jruby_art folder so it can co-exist with a ruby-processing install (~/.rp5rc), but not on the Mac.

# Example YAML configuration file for jruby_art on macosx
PROCESSING_ROOT: /Applications/Processing.app/Contents/Java
# important sketch_book path may be different for processing-3.0
sketchbook_path: # user defined path, to pick up video/audio libraries etc
# set false if you haven't installed jruby, avoids need for --nojruby flag
JRUBY: false # uses jruby-complete by default for running skethes
template: bare # use class or emacs for alternative templates

Note that if you install processing using Home Brew you will need to prefix path to PROCESSING_ROOT with your home directory:- /Users/monkstone/Application/Processing.app/Contents/Java

If you can/are using rvm or rbenv switch to using jruby-9.2++ then

gem install jruby_art

if you are brave (or sensible) and have done an independent jruby install

jruby -S gem install jruby_art # then install other gems eg toxiclibs the same way

but you might find regular MRI gem install works (also tends to be quicker)

gem install jruby_art

After installing the the gem you can download and install jruby-complete (but this is not absolutely required if you have an installed jruby since jruby_art-1.1.0). This is not included in the gem, because it would make it too big, providing you’ve got wget installed all you need to do is:-

k9 --install # downloads and installs jruby-complete and samples

Running examples

To run a bunch of the samples as a demo:-

cd ~/k9_samples
rake # autoruns a bunch of files as a demo
cd ~/k9_samples/contributed # for example
rake # autoruns files in contributed folder
k9 --run jwishy.rb # run the JWishy sketch, using an installed jruby
cd ~/k9_samples/processing_app/topics/shaders
rake # autoruns shader sketches
k9 --run monjori.rb # run single shader sketch, since jruby_art-1.0

Creating your own sketch

All we ask is that you obey the ruby filename convention (ie snakecase) and we can create a template sketch for you as follows:-

k9 --create fred_sketch 200 200 # creates a bare sketch fred_sketch.rb (see below)
vim fred_sketch.rb
:!k9 -r % # from vim runs the sketch

other editors are available

def setup
  sketch_title 'Fred Sketch'

def draw


def settings
  size 200, 200
  # smooth # here

PS: k9 -c fred also works with a bare template defaults, to size 200 200

Read more about using the processing api here