Andrew Glassner 
Processing for Visual Artists [PDF ebook] 
How to Create Expressive Images and Interactive Art

Walk with veteran author Andrew Glassner; see exactly how each of his pieces evolves, including the mistakes he’s made along the way (and how to fix them!), and the times when he changed direction. As your knowledge and skills grow, you’ll understand why Processing is such a powerful tool for self-expression. It offers a 21st-century medium for expressing new ideas. This book gives you everything you need to know to explore new frontiers in your own images, animations, and interactive experiences.