Processing: Creative Coding and Computational Art

message comes up on the bar in the message area of the Processing editor window that
says Expecting SEMI . . .. Fortunately, the Processing/Java compiler is smart and keeps you
from making too big a goof-up. If you happened to try this, just put the semicolon back,
and the program should compile fine. You’ll notice almost all the rest of the lines of the
program have the same basic structure, each calling a function. As I mentioned previously,
the line // keeps a stroke from showing up around the circle is a single-line comment.
The line noStroke(); is a function call that doesn’t pass any arguments. noStroke()
affects how things are painted to the screen. The function call disables a stroke or outline
from being rendered on a shape. I’ll be covering Processing’s drawing and painting functions
a lot in future chapters. The line print("Hello Earth!"); is a call to the print()
function that expects an argument of type String. In this case, you passed in your "Hello
Earth!" argument. You should have seen the words Hello Earth come up in the black text
area at the bottom of the Processing editor window. String is a type of data in Processing
(or most any program) for referencing groups of characters. print() is an important function
that you’ll use all the time in Processing to help you debug your code. Processing has
an alternate version, println(), which does the same thing as print(), but adds a return
after printing the string argument within the parentheses. For example, if you run the following
code:
print("hello");
print("earth");
the output will be as follows:
helloearth
If you use the println() version, as follows:
println("hello");
println("earth");
the output will look like this:
hello
earth
The rest of the function calls in the program, Background(0), fill(80, 220, 255), and
ellipse(100, 100, 100, 100), set the background color, set the shape fill color, and create
the circle, respectively. I will be covering these and other Processing graphics functions
in more depth beginning in Chapter 6.
Curly braces
Another important and widely used syntactical structural element is the curly brace: { }.
Curly braces, which always work in balanced pairs (an open and closed pair), are used to
structure blocks of code. Following are some code examples that show the use of curly
braces.
CODE GRAMMAR 101
61
3