If the program used them in several places, that would be an improvement, but it doesn't. It's maybe a little bit atypical, but nearly all of the things it calls from Processing, it calls in exactly one site: the above, plus color_mode, no_stroke, smooth, background, and rect.

It does call fill from four call sites, but that was because there's no reasonable way to return a list of four arguments from a method in Ruby, as far as I can tell.