LCC 6310 Computation as an Expressive Medium

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LCC 6310Computation as an Expressive Medium

• Lecture 1

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Overview

• Go over the syllabus
• Brief introduction to me and my work
• Art, programming and Java

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Syllabus
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Background

• Ph.D. in Computer Science
• Expressive AI Artificial Intelligence-based art
  and entertainment
• Worked in industrial research labs (Intel,
  Tektronix) doing HCI research
• New at Georgia Tech arrived in January

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AI Art
Black and White, 2000
The Senster, 1970
Edward Ihnatowicz
Peter Molyneux (Lionhead)
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Work
Façade interactive drama
Terminal Time interactive video
Office Plant 1 robotic sculpture
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Façade

• Dramatic world inhabited by computer controlled
  characters (believable agents)
• The user (player) plays a protagonist within the
  story, first-person point of view
• The player experiences a story with a dramatic arc

Collaborator
Andrew Stern, independent artist and researcher
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Terminal Time
Goal trees (ideology)
Historical events
Audience feedback
Collaborators
Steffi Domike, Design Department, Chatham College
Paul Vanouse, Art Department, SUNY Buffalo
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Office Plant 1

• Creates a background presence
• Sorts incoming email into social and emotional
  categories
• Behavior is a function of the email received

Collaborator
Marc Bohlen, Media Studies, SUNY Buffalo
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Combine AI research and art
Expressive AI
Artistic practice
AI research
AI methods and technology suggest new audience
experiences
Wrestling with meaningful human experiences
suggests new AI research directions
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Some directions

• Im someone to chat with about
• Interactive story (particularly procedural
  approaches)
• Robotic sculpture
• Video games as a cultural practice (design and
  technology)
• Meta-art (generative systems)

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Introduce yourselves
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Programming languages

• Abstract, human understandable language for
  telling computer what to do
• The abstract language must be translated into the
  low level language understood by the machine
• This translation is accomplished by an
  interpreter or compiler
• We will be learning the compiled language Java

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A simple Java program
class PrintLoop public static void
main(String args) for (int i 0 i lt 10
i) System.out.println("i " i)

Just prints the numbers 0 to 9 on the screen
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Human readable is relative
class PrintLoop public static void
main(String args) for (int i 0 i lt 10
i) System.out.println("i " i)

Java compiler translates this into
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Java VM assembly code
public static void main(java.lang.String)
Code 0 iconst_0 1 istore_1 2
goto 30 5 getstatic 8 new 11
dup 12 ldc 14 invokespecial 23 17
iload_1 18 invokevirtual 27 21
invokevirtual 31
24 invokevirtual 34 27 iinc 1, 1
30 iload_1 31 bipush 10 33 if_icmplt
5 36 return test.PrintLoop() Code 0
aload_0 1 invokespecial 43 4
return
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Object Oriented vs. Procedural Languages

• Procedural (e.g. C)
• We create some data representing an image (array
  of pixels to draw on the screen)
• We write a procedure than can be passed the image
  and will draw it

• Object Oriented (e.g. Java)
• We create a class that contains an image AND a
  routine draw it
• The data and the behavior (ability to draw) are
  in one "container"

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A couple of Javas relatives

• Smalltalk 80
• Alan Kay and the Dynabook (PARC)
• C
• Managing big C programs Bjarne Stroustrup

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Smalltalk 80

• Alan Kay and the Dynabook (PARC)
• Developed idea of a general purpose computer to
  be used by normal people!
• Highly interactive interface
• Included concept of windows!
• Smalltalk 80 end users could create their own
  tools

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Smalltalk 80

• Includes objects
• Objects contain data and procedures
• Procedures in objects are called methods
• All computing is done by sending a message to an
  object asking it to perform one of its method
• Objects are defined by classes

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C

• Managing big C programs Bjarne Stroustrup
• Started as "C with Classes" idea borrowed from
  Simula 67 Smalltalk
• Goals
• Organize programs as classes with inheritance
• No performance penalty compared to C
• Thus somewhat dangerous!!!
• C is converted into C

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Java

• Designers started with C
• Smaller
• Simpler
• Safer
• Programming embedded systems
• Toasters, microwave ovens, TV set top boxes
• Reliability very important--avoid costly recalls
• Web programming
• Incorporated into web browsers at critical moment

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The virtual machine

• Since Java was designed to run on embedded
  systems, it was designed around a virtual machine
• Write once, run everywhere

PC
Mac
Cell Phone
Java VM
Java VM
Java VM
Windows
OS X
Phone OS
Processor
x86
G3/4/5
Java Machine
Java OS
Java VM
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Steps for running a Java program
Execute program
OS-specific Object Code
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Structure of Java programs

• Create one or more Java source files
• Compile each source file into a class file
• An application consists of these class files (not
  a single file like a .exe)
• To run the program, send one of the class files
  to Java
• This entry file must have method called main
• public static void main(String argv)

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Sample application
File HelloWorld.java

• public class HelloWorld
• public void greet()
• System.out.println("Hello World!")
• public static void main(String argv)
• HelloWorld hw new HelloWorld()
• hw.greet()

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Java file and class names

• Source code files must have the ".java"
  extension.
• The file name should match the class name. The
  class name should start with a capital letter.
  This naming convention is enforced by most
  reasonable compilers.
• A file containing
• class HelloWorld
• must be named HelloWorld.java
• Compiled bytecode has the ".class" extension

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Compiling HelloWorld
HelloWorld.class
javac
javac HelloWorld.java
0xCAFEBABE ...
javac is the Java Compiler
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Executing HelloWorld
java HelloWorld
java is the Java Virtual Machine
Cgtjava HelloWorld Hello World! Cgt
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Object Oriented Programming

• OOP is all about programming using something
  called an object.
• Objects are created from classes. An object is
  called an instance of a class.
• Objects do useful stuff by calling methods on
  them.
• Lets look at classes and objects in more detail.

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Previously...

• public class HelloWorld
• public void greet()
• System.out.println("Hello World!")
• public static void main(String argv)
• HelloWorld hw new HelloWorld()
• hw.greet()

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A Class
A class will be used to define how objects made
from this class will operate

• class Greeter
• String greeting
• public Greeter(String newGreeting)
• greeting newGreeting
• public void greet(String name)
• System.out.println(greeting ", " name)

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Field
A class typically will have one or more
fields which are the data items which the object
holds

• class Greeter
• String greeting
• public Greeter(String newGreeting)
• greeting newGreeting
• public void greet(String name)
• System.out.println(greeting ", " name)

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A Constructor
Classes can have Constructors which contain code
only run when an object is created. Useful for
initialization

• class Greeter
• String greeting
• public Greeter(String newGreeting)
• greeting newGreeting
• public void greet(String name)
• System.out.println(greeting ", " name)

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A Method
Once created an object can be asked to run a
"method" which will do something
normally involving data stored by the
object (plus sometimes data passed in.)

• class Greeter
• String greeting
• public Greeter(String newGreeting)
• greeting newGreeting
• public void greet(String name)
• System.out.println(greeting ", " name)

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Another Class
This class is just being used to hold a main
method. Here we make two Greeter objects and use
them

• class Driver
• public static void main(String args)
• Greeter g1 new Greeter("Hello")
• Greeter g2
• g2 new Greeter("Good morning")
• g1.greet("Bob")
• g2.greet("Mary")
• g1.greet("Sam")
• g2.greet("Joan")

Cgtjava Driver Hello, Bob Good morning,
Mary Hello, Sam Good morning, Joan Cgt
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OOP

• OOP consists of designing a bunch of classes most
  of which are used as templates to make objects
• The objects are used to hold data
• They are initialized with constructors and
  perform useful functions by being asked to run
  their methods