Processing

Dr Andy Evans

Processinghttp://processing.org/MIT Media Lab

Libraries for visualisation.

Wraps a simple visualisation scripting language inside java classes.

Also javascript /Android / iPhone javascript versions.

Excellent community with a positive attitude to open sourcing good code.

Processing Development Environment

Small put perfectly formed IDE.Saves as Applications, MPEG, SVG and PDFs.Bundles everything (data, libraries) into jars. Constructs executables.

Coding

Two important methods:

void setup(){ }

Runs once at start.

void draw(){}

Runs each frame until stopped (60 frames s-1; but can be changed).

Coding

float x = 0;float y = 100;float speed = 1;

void setup() { size(200,200); // Size has to be first thing in setup}

void draw() {

background(255); // Wipe the background white

x = x + speed; // Change x location

if (x > width) { // Reset if it runs of the screen. x = 0; }

fill(0); // Paint a rectangle rect(x,y,30,10);}

Objects

In the PDE you can put code in different tabs. However, you can also just put multiple classes in one tab.

Processing will wrap them all inside its own class, as ‘inner classes’.

Java developmentExtend the Processing wrapper PApplet.

Add in your Processing code.

If you want it to run as an application, add:

public static void main(String args[]) {

PApplet.main(new String[] {

"--present", "MyProcessingSketch“

});

}

For multiple classes you need to get a reference to the Papplet class into your class then call, e.g.

papplet.draw();

Eclipse

There is an Eclipse plugin:http://wiki.processing.org/w/Eclipse_Plug_In

However, you can write just as well without it:http://processing.org/learning/eclipse/

If you run as an applet in Eclipse and want to run as an application, go into File -> Properties and delete the Launch Configuration or use the arrow on the run button to “Run As”.

Processing tips

Processing creates a project ‘sketchbook’ directory called after the main file for each project. It expects to find all data in a data directory in here. Libraries should also be in a ‘libraries’ directory, though better to just ‘Add File’ them.

Avoid variable names it might already use, like pixels, x, y, and z.http://forum.processing.org/topic/reserved-keywords-wiki-page

If you separate classes in to other files, call them, e.g. “Car” rather than “Car.java” – the latter signals that Processing should treat it as Java, and you’ll need to import the classes etc.

Other Processing

Libraries for:XML / GPS interaction / Network communicationsConnections with Ruby/Python/JavascriptVideo / SoundCommunications with hardwareWebcam and motion recognition

Spinoff projects:Wiring/ Arduino – chipboards for hardware development

Book

Great book on processing, but also modelling real systems more generally, is:

Visualisation inspiration

http://visual.ly/http://www.visualisingdata.com/Books:

JFreeChart developer guide.Processor books (see website)Visualisation books by Edward Tufte