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Introductory lecture on the use of the "processing" language and environment for teaching media processing and interaction design.

Introduction

This introduction is based on Daniel Shiffman's tutorial .

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.
Moreover, by means of Export Application it is possible to generate an executable application for Linux, MacOS, or Windows platforms.

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.

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Source:  OpenStax, Media processing in processing. OpenStax CNX. Nov 10, 2010 Download for free at http://cnx.org/content/col10268/1.14
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