From the Processing website:

"Processing is a flexible software sketchbook and a language for learning how to code within the context of the visual arts. Since 2001, Processing has promoted software literacy within the visual arts and visual literacy within technology. There are tens of thousands of students, artists, designers, researchers, and hobbyists who use Processing for learning and prototyping."

Try Processing online

Some of my sketches at OpenProcessing

Saskia's Tiles

Inspired by Saskia, coded by me

Cafe Wall Illusion

cafe wall illusion

Wikipedia's entry about the Cafe Wall Illusion. View on OpenProcessing - it's a bit more interactive. My eyes, my eyes...

3D Random Walk

View sketch at OpenProcessing (doesn't work so well on mobile devices)

Animated Tiling

Tiling animation

View sketch at OpenProcessing