Processing: Creative Coding and Computational Art

entering CMD). When using a command-line shell instead of a GUI shell, you need to be
explicit when issuing commands. It is common for modern GUI shells to hide the suffixes
of files. In OS X, to launch the Calculator application using the Finder (GUI shell), you
double-click the calculator icon, named simply “Calculator.” In contrast, from the Terminal
application (command-line shell), you need to type: open Calculator.app. In addition, you
need to be explicit as to where files reside (the path) to access/launch them. When using
relative paths with Processing’s open() command, you need to provide path addresses in
relation to the Processing application. For example, the Processing application on my computer
lives within a Processing directory, which lives in the Applications directory. The
Calculator application also lives within the Applications directory. To launch the
Calculator on a mouse press, I can use the following Processing sketch:
void draw(){
}
void mousePressed(){
open("../Calculator.app");
}
The open() command also allows to you pass a String argument. You can read more
about open() at http://processing.org/reference/open_.html.
Web
The Web section includes the functions link(), param(), and status(). Stating the obvious,
these functions involve web-based features and are used within a browser environment.
link() allows you to load a web page, as well as specify which browser window to
use (the existing one or a new one). param() reads the value of a parameter, specified
within the HTML of a web page. For example, if you have the following HTML in the page
holding an applet, created from a sketch named SimpleBall:
you can use the param value ballradius in your SimpleBall sketch:
// SimpleBall sketch
String strgRadius = param("ballradius");
int radius = Integer.parseInt(strgRadius);
size(200, 200);
ellipse(width/2, height/2, radius, radius);
You’ll notice that the param value comes back as a String, so it needs to be converted to
a number. Integer.parseInt() is a static method of Java’s Integer class that converts
strings to integers. (Remember, in Processing, you can use Java code along with Processing
code.)
status() allows you to display messages in the browser’s status area—normally in the
lower-left corner of the browser.
PROCESSING LANGUAGE API
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