Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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rounds down, and round() rounds the normal way—to whichever value is closer. There is
a function to calculate distance (dist()), square roots (sqrt()), maximums (max()), and
minimums (min()). Many of these functions can be considered convenience functions, in
the sense that it’s possible to use other existing code structures in Processing to derive
your own routines for these functions. That said, it really doesn’t make a whole lot of
sense to re-create perfectly fine (and very likely more efficient) existing code.
Trigonometry
Trigonometry rocks! I know this might sound like a shocking and absurd statement to
many of you (or you’ve already written me off as a major geek and have come to expect
it). Trig allows you to do very cool things with code that would be a major pain without it.
Some of these things include wave generation, firing projectiles/aiming, 2D and 3D rotations,
and any type of organic motion. I cover trig in Chapter 4, in the section entitled “The
Joy of Math,” as well as in Appendix B; and (in case you haven’t noticed), I’ve also been
using it in many of the code examples throughout the book.
The Trigonometry section includes nine functions: the basic three and their inverses (sin(),
cos(), tan(), asin(), acos(), and atan()); two useful utility functions (degrees() and
radians(), which convert between these different units of measure); and atan2(), a variation
on atan(). Remember that trig functions expect angles in radians, not degrees.
Without the radians() function, you’d have to take all your angles, multiply them by pi,
and then divide by 180 to convert to radians; it’s much simpler to write radians(angle in
degrees). The atan2() function is really handy for aiming and shooting stuff on the
computer—two things my seven-year-old son can’t seem to get enough of (in spite of his
peacenik, granola-eating parents’ best intentions).
Random
The Random section includes five functions involved in random number generation. In
practically every piece of software art I create, I include some random processes.
Randomization brings an organic quality to the coding process, as well as a sense of continuous
discovery. Processing has two random generators: random() and noise().
random() is the far simpler function, and the one I use most often. It works by receiving
either one or two arguments, as in
or
random(1)
random(1, 10);
The first case generates a random float value between 0 and the argument (in this case,
1). The second version generates a random float value between the two arguments (1
and 10). If you need the returned value to be an integer, you’ll need to convert the result
using a statement such as the following:
round(random(1, 10));