Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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able to handle billions of operations per second, but each process is still distinct. The illusion
that a single computer processor is handling simultaneous events is a function of our
relatively slow eyes and their inability to see the tiny delays.
Event handling
Returning to Processing and Java’s event mechanism, if we don’t need to create our own
loop to detect events, how is it done? Java’s runtime environment, the Java Virtual
Machine (JVM), takes care of it for us. In addition, there is an Event class that encapsulates
event properties and methods. When an event occurs, the Event class detects it and in a
sense broadcasts it throughout the program. How we receive the broadcast and what we
do with it is mostly what we have to worry about. This efficient system makes event handling
relatively easy in Java and, as you might suspect, even easier in Processing. Here’s a
simple interactive example in which you can click the screen to randomize the sketch. The
event detection code in the example happens within the if statement in the draw() function,
checking the mousePressed condition. When the mouse is pressed, the condition
evaluates to true and the setRandomStyle() function is called.
// click to randomize
float x, y, squareSize;
color bgColor, strokeColor, fillColor;
float strokeWt;
void setup(){
size(400, 400);
rectMode(CENTER);
x = width/2;
y = height/2;
setRandomStyle();
frameRate(30);
}
void draw(){
background(bgColor);
strokeWeight(strokeWt);
stroke(strokeColor);
fill(fillColor);
rect(x, y, squareSize, squareSize);
if (mousePressed){
setRandomStyle();
}
}
void setRandomStyle(){
bgColor = color(random(255), random(255), random(255));
strokeColor = color(random(255), random(255), random(255));
fillColor = color(random(255), random(255), random(255));
strokeWt = random(5, 100);
squareSize = random(10, 300);
}