Programming in processing  (Page 14/3)

Introduction

Processing is a language and development environment oriented toward interaction design . In the course Media Processing in Processing (MPP) , processing is one of the main instruments used to introduce some fundamentals insound and image processing. Processing is an extension of Java that supports many Java structures with a simplified syntax.

Processing can be used in three

Programming modes

• Basic

  Sequence of commands for simple drawing by graphic primitives. --

  applet without nose

  size(256,256); background(0);stroke(255); ellipseMode(CORNER);ellipse(72,100,110,130); triangle(88,100,168,100,128,50);stroke(140); strokeWeight(4);line(96,150,112,150); line(150,150,166,150);line(120,200,136,200);

• Intermediate

  Procedural programming --

  applet with nose

  void setup() { size(256,256);background(0); }void draw() {stroke(255); strokeWeight(1);ellipseMode(CORNER); ellipse(72,100,110,130);triangle(88,100,168,100,128,50); stroke(140);beginShape(TRIANGLES); vertex(114, 180);vertex(mouseX, mouseY); vertex(140, 180);endShape(); strokeWeight(4);line(96,150,112,150); line(150,150,166,150);line(120,200,136,200); }

• Complex

  Object-Oriented Programming (Java) --

  applet with colored nose

  Puppet pinocchio;void setup() { size(256,256);background(0); color tempcolor = color(255,0,0);pinocchio = new Puppet(tempcolor); }void draw() { background(0);pinocchio.draw(); }class Puppet { color colore;Puppet(color c_) { colore = c_;} void draw () {stroke(255); strokeWeight(1);ellipseMode(CORNER); ellipse(72,100,110,130);stroke(colore); beginShape(TRIANGLES);vertex(114, 180); vertex(mouseX, mouseY);vertex(140, 180); endShape();strokeWeight(4); line(96,150,112,150);line(150,150,166,150); }}

The Processing programs can be converted into Java applets. In order to do that, one just goes to the File menu and chooses Export . As a result, five files will be created and put in an applet folder:

• Index.html

  html code to visualize the applet

• Filename.jar

  the compiled applet, including all data (images, sounds, etc.)

• Filename.pde

  the Processing source code

• Filename.java

  the Java code embedding the Processing source code

• Loading.gif

  an image to be displayed while the applet is being loaded.

Data types

Variables

A variable is a pointer to a memory location, and it can refer either toprimitive values ( int , float , ecc.) or to objects and arrays (tables of primitive-typeelements).

The operation of assignment b = a produces

• The copy of the content of a into b , if the variables refer to primitive types.
• The creation of a new reference (pointer) to the same object or array, if the variables refer toobjects or arrays.