Processing: Creative Coding and Computational Art

void setup(){
// create new rectangle object
new Rectangle();
}
// class description
class Rectangle {
}
This is all it takes to create a class in Processing. Of course, this class won’t do anything, but
it’s a start. To create a class, you use the class keyword followed by the name of the class.
You capitalize the name of your classes. To create an object from the Rectangle class, you
use the new keyword. Typically, you also assign the new object to a variable so that you can
refer to it later in your program. In the last example, even though I created a Rectangle
object, I can’t communincate with it, as there is no variable assigned a reference to the
object. Figure 9-29 shows an improved (and more useful) version of the last sketch:
// object (reference) variable
Rectangle r1;
void setup(){
// create new rectangle object
r1 = new Rectangle(100, 200, 150, 150);
}
// class description
class Rectangle {
//class constructor
Rectangle(int x, int y, int w, int h) {
println("x pos = "+ x+"\ny pos = " + y);
println("width = "+ w+"\nheight = " + h);
}
}
Figure 9-29. OOP println() output example
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