Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
760
Figure B-6. Sine Console sketch
Bitwise Operations
If you look at what the Processing language reference has to say about the red() function,
there’s a mysterious blurb under the description section:
“The red() function is easy to use and understand, but is slower than another technique.
To achieve the same results when working in colorMode(RGB, 255), but with greater
speed, use the >> (right shift) operator with a bit mask.”
The terms right shift operator and bit mask can be generally grouped under the heading
of bitwise operations. I briefly mentioned bitwise operations in Chapter 10 and in
Appendix A, but next I’ll provide a detailed account of how they work and why you might
want to learn them.
A word of caution: Bitwise operations can be daunting for beginners (actually even
experienced coders) and are an advanced topic. Though they can be difficult to get
your head around, bitwise operators are also powerful and highly efficient processing
tools and certainly worth (eventually) learning about.
As part of my research for the book, I did a web search on bitwise operations, and was surprised
at how poorly they were explained—including in my trusted Wikipedia. There are
plenty of bitwise operation examples, but I had trouble finding a really clear elucidation—
especially for new programmers. Thus, I have taken this challenge on, as a personal mission,
to demystify the mass confusion and escalating anxiety over bitwise operations (at
least in their relation to Processing and color).
First of all, what the heck are bitwise operations, and why are they in Processing in the first
place, especially if they’re not easy to use? Bitwise operations are super-low-level mathematical
operations, down at the binary or bit level. Rather than dividing 4 by 2 like 4/2, I
could get the same answer (2) using a bitwise operation, which would look like 4>>1, or
even 4^6. Yikes, why would I want to do that?! Well, most of the time I wouldn’t. However,
there are some good reasons to break out bitwise operations (as well as some really geeky
low-level reasons that most of us Processing types are not gonna want/need to do). Color