Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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Figure 3-2. Completed stepped radial gradient
I begin the program with my standard “about the program” comments. Then I declare
some global variables at the top of the program. Global, as opposed to local, means that
the variables will be available from any place within the program. Later, when I cover functions,
I’ll discuss this concept, called scope, further. You’ll notice I declared all the variables
as type int. The line int gradientWidth, gradientHeight; declares both gradientWidth
and gradientHeight variables as type int in one line. When declaring and initializing variables,
you can put them on individual lines or bunch them together. For example, the
following line is perfectly legal:
int var1 = 3, var2 = 5, var3 = 6, var4 = 0;
I declare four variables of type int, while also initializing them with initial values.
After declaring variables, I set the size properties and background color of the sketch
window:
size(200,200);
background(0);
You might recognize these as function calls, in which dimensions (width and height) and
color arguments are passed to the respective Processing functions. These functions are
built into the Processing language, which is why you don’t see the functions defined in the
program anywhere. After you set the sketch window dimensions using the size(200, 200)
command, you can then retrieve the sketch window size using Processing’s built-in global
properties: width and height. You’ll notice these words turn a reddish color in the editor
when you type them in, letting you know they are built-in properties in Processing.