Processing is an open source programming language and integrated development environment (IDE) built with Java
Processing is a programming language, development environment, and online community. Since 2001, Processing has promoted software literacy within the visual arts and visual literacy within technology. Initially created to serve as a software sketchbook and to teach computer programming fundamentals within a visual context, Processing evolved into a development tool for professionals. Today, there are tens of thousands of students, artists, designers, researchers, and hobbyists who use Processing for learning, prototyping, and production.
» Free to download and open source
» Interactive programs with 2D, 3D or PDF output
» OpenGL integration for accelerated 3D
» For GNU/Linux, Mac OS X, and Windows
» Over 100 libraries extend the core software
The source code can be found on their Github