I have just updated the development version of ruby-processing
https://github.com/ruby-processing/JRubyArt to version 0.0.5 and it
features my vecmath library written as a java extension. I have also
written up the creation of the java extension here
which might be of interest to others trying to create java extensions:-
There are examples of methods that take variable numbers of arguments,
take an optional block etc etc. I learned this all by trial and error,
so I would also welcome any comments.