Processing
Source code for the processing core and development environment
...There are tens of thousands of students, artists, designers, researchers, and hobbyists who use processing for learning and prototyping. The core Processing software is augmented by libraries and tools contributed through the community. These inventive extensions are a bright future for the project. We have a list of Contributed Libraries and Contributed Tools posted online. These contributions can't be underestimated. The Processing Development Environment makes it easy to write Processing programs. It’s free and open source! Read the tutorial, which will guide you through the basics of Processing.