Are you sure you can use Piccolo2D with Processing? I know it as a something with its own rendering method, so it is more concurrent of Processing (in a different domain, higher level with its scenegraph) than complementary. I can be wrong, of course.

I'm really not sure, but at the libraries page in processing.org there is the following entry:

Ah, I didn't know such library existed. It is GPL, so it is a no-no for me, as I don't want to release my code under this license (I prefer less constraining licenses, like the Piccolo2D one, based on the BSD one).
I suppose the author changed the back-end of Piccolo2D from Java2D to Processing. Perhaps look at the Piccolo2D examples, they are quite complete.
The scenegraph and zoomable interface can be useful in Processing, indeed.

OK, thank you! You always reply fast, I noticed from other topics!