Processing: Creative Coding and Computational Art

Hopefully, you were able to successfully run this sketch. I created an alternative rendering
option as well, which you can mess with in a bit. When you run the sketch, you should see
many (actually 500) white balls moving randomly around, bouncing off the edges of the
window. This code is not simple, so don’t feel bad if it is a struggle to understand it. You’re
going to be doing a lot more of this type of coding beginning in Chapter 6—so this is really
more like a teaser than something you need to fully grasp at this point. I just thought it
was good to show you something a little more interesting after all the hard work you’ve
been putting in. The main concept I want to reinforce at this point is the power of arrays
and loops. Let’s look at the program in sections:
// global variables
int ballCount = 500;
int ballSize = 8;
int ballSpeed = 3;
float[]xspeed = new float[ballCount];
float[]yspeed= new float[ballCount];
float[]xpos = new float[ballCount];
float[]ypos = new float[ballCount];
float[]wdth = new float[ballCount];
float[]ht = new float[ballCount];
After my comments, I declare and initialize some global variables; these variables will be
accessible throughout the entire program. I chose the specific data type, in this case int or
float, based on the type of value that would need to be stored in the respective
variables/arrays. Obviously, ballCount could be an integer value, but a speed value would
need to be a float value. The arrays are initialized with enough memory to hold the total
number of balls. Remember, I can’t change the arrays’ sizes once they’re initialized (in
truth, you’ll see later that there are indeed functions to do such a thing), so it’s important
to make them big enough at the beginning. Although the arrays are initialized to each hold
500 values (based on ballCount), there is still nothing in them.
//initialize sketch
void setup(){
//set sketch window size and background color
size(400, 400);
background(0);
//initialize values for all balls
for (int i=0; i