Processing Dr Andy Evans

Processing 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 development Extend 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: However, you can write just as well without it: 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. 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 communications Connections with Ruby/Python/Javascript Video / Sound Communications with hardware Webcam 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 Books: JFreeChart developer guide. Processor books (see website) Visualisation books by Edward Tufte