Processing: Creative Coding and Computational Art

Figure 6-25. Auto Layout sketch
This sketch utilizes a fair amount of variables, so it might look a bit confusing. Definitely
take your time going through it. I think the auto-layout feature is worth taking the time to
understand, as this type of process is quite valuable when you’re doing visual stuff. You’ll
also notice that I initialized a second local variable (j) in the for loop head, which I use to
cycle through the caps[] array. There is also a conditional statement that keeps resetting
j to 0, ensuring that the index of the array stays within bounds. Remember, arrays are
zero-indexed—so if you have three items in an array, the last index number will be 2, or
array.length-1. If you make a request to access an index position in an array that doesn’t
exist, you’ll get an error. This is a very common mistake, and usually pretty easily (and
happily) resolved.
I also snuck in some formatting that hopefully will look quite suspect: if (j>2) j=0;. This
is actually a normal conditional statement that I put on one line, leaving off the curly
braces. Yes, this is legal code, as long as you only use one statement in the block of the
code (between where the curly braces would have been). You can even use an else statement
after the if block—but again, only one line of code will be recognized by the structure
if you don’t include curly braces. You’ll also get a compiler error if you include the
else and have more than one line in the if block. Regardless of how you format your if
statement, it makes no difference whether you put it on one line or skip a line between
each part (at least to the compiler). Whitespace is ignored by the compiler, except if it’s
between quotation marks, which it then sees as character spaces. In the next examples, the
first two snippets works fine, but the last two don’t work.
Here’s Example 1, which works:
for (int i =0; i