Introduction to Alice 23 October 2012 Alice is named in honor of - - PDF document

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Introduction to Alice

Alice is named in honor of Lewis Carroll’s Alice in Wonderland Slides Credit: Joel Adams, Alice in Action With thanks to John Magee for his guidance about these materials

CS101 Lecture 16

23 October 2012

Alice

A modern programming tool

3-D graphics 3-D models of objects

Animation

Objects can be made to move around the virtual world (a video game or simulation implemented in 3-D)

Two kinds of animations:

Movie: passive user watches the animation Interactive: active user clicks on mouse, types a key

• n keyboard …

Actions of user are called events

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Demo: Getting started

Starting Alice Load and run a world

FairyCourt(movie) HelicopterSimulation(interactive) First program: Alice and WhiteRabbit welcome us to their world (movie)

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Getting and Running Alice

Alice software is freely distributed Downloading Alice

Go to the website: http://www.alice.org Click the link Get Alice 2.3 Click download link specific to your operating system Save Alice.zip (or Alice.dmg) to your PC

Installing and running Alice

Extract Alice from Alice.zip (or Alice.dmg) file Create desktop shortcut (alias) to Alice.exe Double-click Alice icon to launch Alice application

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The Alice Tutorials (continued)

Go through the tutorials to learn the basics of Alice

Alice in Action with Java 6

Program Design

We don’t start with writing program code, very much the same as filmmaker don’t start with filming, rocket scientists don’t start with building rockets We start with design! Design is very important and affects the correctness and efficiency of the solution Design needs to revised, improved…

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Alice in Action with Java 7

Algorithms

An algorithm is a sequence of steps to solve a problem or perform a task Example algorithms:

Driving directions Cooking instructions Installation instructions Algorithms for search of records in phonebook, database, web… Algorithms for displaying, editing, animating pictures… The flow of a user story in an animation

Algorithms are generally not tied to programming languages

Their implementations are

Alice in Action with Java 8

User Stories

Contain

Basic description of what happens when program runs Nouns in story (Alice, the White Rabbit) correspond to

• bjects

Verbs correspond to actions, responses to messages Chronological flow describes the sequence of the actions

When the program begins, Alice and the White Rabbit are facing each other, Alice on the left and the White Rabbit on the right. Alice turns her head and then greets us. The White Rabbit also turns and then greets us. Alice and the White Rabbit introduce

• themselves. Simultaneously, Alice and the White Rabbit say

“Welcome to our world.”

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Alice in Action with Java 9

Program Design

For a given user story

plan scenes and shots

Scene: a piece of the story usually set in one location Shot: part of scene told with camera in one position

Create storyboards

Alice in Action with Java 10

Transition Diagrams

Link the multiple storyboard-sketches In a movie, transition diagram is a linear sequence In the first Alice program, there will be 7 actions

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Alice in Action with Java 11

The Flow of User Story

A numbered sequence of objects and actions

• 1. Alice turns her head toward the user
• 2. Alice greets the user
• 3. The white rabbit turns toward the user
• 4. The white rabbit greets the user
• 5. Alice introduces herself
• 6. The white rabbit introduces himself
• 7. Simultaneously, Alice and the white rabbit say

“Welcome to our world.”

Alice in Action with Java 12

Programming Implementation in Alice

Templates provide a basic world environment Sample program is based on the “grass” Template Areas in the Alice window

Menus: includes File, Edit, Tools, and Help Buttons: includes Play, Undo, and Redo Object tree: lists all world objects; e.g., ground Details area: includes properties, methods, functions World window: displays graphic objects in a program Editing area: includes editing space and controls Events area: contains actions responding to events

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Alice in Action with Java 13

Programming Implementation in Alice (continued)

Alice in Action with Java 14

Program Style

Change program display styles in Preferences How to access Preferences dialog box

Click the Edit menu Click the Preferences choice

Selecting a display style in Preferences dialog

Click next to “display my program” in General tab Select a style

Style recommended for course: Java Style in Color

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Alice in Action with Java 15

Program Style (continued)

(We are aware of a problem with this setting. It’s ok to keep it as Alice style.)

Demo: A new world

Create a new world

File  New Choose template

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Objects

An "object" is

any thing that can be identified as unique from other things

How is an object unique?

has a name has properties:

width, height, color, location

can perform actions (methods):

associated actions it can perform tasks it can carry out

Object Parts

Objects may be composed of parts

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Class

Objects are categorized into classes Each object is an instance of the class. All objects in a class have similar properties and generally can perform the same tasks.

Person Dogs

peter mary paul spike scottie fluffy

Alice in Action with Java 20

Adding Objects to Alice

Class: blueprint for an object How to populate Alice world with objects

Click Add Objects button in world window Locate class specifying the object in the Alice Gallery Right-click class and select “Add instance to world”

Objects in sample world: aliceLiddell and whiteRabbit Naming conventions for objects and classes

Class: capitalize all words; e.g., AliceLiddell Object: capitalize all but first word; e.g., aliceLiddell

Objects can be renamed from the object tree

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Demo: Adding objects Galleries

Classes (3D models) are found in the galleries

Local gallery (installed with the software)

Minimum or complete options

Web gallery

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Alice in Action with Java 23

Adding Objects to Alice (continued)

Demo: Saving a world

Writing and testing an animation is an intense load on the computing system – a crash can occur.

Best solution:

save your world every 15 minutes

(Or at least every half hour)

also save to a backup system (for example, a zip disk or memory key)

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Alice in Action with Java 25

Accessing Object Subparts

Bounding box: encloses any Alice object Impact of selecting an object in the object tree

Bounding box is drawn around object in world window Details area adapts to the selected object

First action to program: Alice turns head to user First set of programming steps

Select + sign next to aliceLiddell in object tree Select + sign next to neck subpart Select head (bounding box is drawn, details change) Drag doInOrder control to top of editing window

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Accessing Object Subparts (continued)

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Alice in Action with Java 27

Accessing Object Subparts (continued)

Alice in Action with Java 28

Sending Messages

Alice programs rely on sending messages to

• bjects

Objects’ methods deliver actions in response to messages Programming Alice’s head to turn

Select Alice Liddell’s head in the object tree Scan through the methods in the details area Click on pointAt() Drag pointAt()to the editing area and drop it Specify camera as the target

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Alice in Action with Java 29

Sending Messages (continued)

Alice in Action with Java 30

Testing and Debugging

Bug: error interfering with normal program functions Debugging: process of removing program bugs Click the Play button to test Alice Liddell application

Alice Liddell’s head will turn toward the user

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Alice in Action with Java 31

Testing and Debugging (continued)

Alice in Action with Java 32

Coding the Other Actions

say() message

Displays dialog for an object Text can be customized by selecting other…

Task: complete first Alice Liddell application

Add Alice Liddell’s initial greeting Point the white rabbit to the user Have Alice Liddell introduce herself Have the white rabbit introduce himself

Customize messages by selecting from more…

Example: adjust fontSize of message text to 25

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Alice in Action with Java 33

Coding the Other Actions (continued)

Alice in Action with Java 34

Statements/Instructions

Statement/instruction: a line or control structure in a program that executes (is carried out by computer at runtime) Program: a set of instructions that tell the computer what to do Basic format of a line in an Alice program

• bject.message(value); more...

Control structures manage other statements

Example: doInOrder contains other statements

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Alice in Action with Java 35

The Final Action

Sequential execution

Actions are performed consecutively Example: actions executed in doInOrder structures

Simultaneous execution

Actions are performed in parallel Example: actions performed in doTogether structure

Finishing the first program

Add doTogether control structure to application Send say( )to aliceLiddell and whiteRabbit Message value: Welcome to our world

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The Final Action (continued)

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Alice in Action with Java 37

Final Testing

First set of actions are performed separately Final actions are performed simultaneously

Alice in Action with Java 38

Final Testing (continued)

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Alice in Action with Java 39

The Software Engineering Process

A methodical, disciplined approach to constructing programs Multiple parts

(problem specification,) design, implementation, testing (, revising..)

Elements of software design

Write the user story Organize nouns and verbs into an algorithm Create storyboard-sketches and the transition diagram

Elements of software implementation and testing

For each noun in the story, add an object to Alice world Match message to verb and send message to object Test message to determine if it produces desired action

Alice in Action with Java 40

Alice’s Details Area

Reflects attributes and behaviors of selected object Three panes: properties, methods, and functions

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Alice in Action with Java 41

The properties Pane

Includes attributes such as color, opacity, visibility Change values to alter object appearance/behavior Example: make the White Rabbit disappear

Click opacity in the properties pane Drag opacity to the editing area Set opacity to 0 Change the duration to 2 seconds

How a program changes when a property is altered

New message is added to editing area In the example above, a set () message is added

Alice in Action with Java 42

The properties Pane (continued)

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Alice in Action with Java 43

The methods Pane

Provides a list of behavior-generating messages In Object Oriented Programming, an instruction targeting an object is said to be a method.

To get an object to perform a behavior, send that object a message that asks it to produce that behavior E.g. aliceLiddle.say(…)

Alice in Action with Java 44

Methods

Alice Objects have predefined methods for basic tasks Additional methods may also be created by Alice developers

Two reasons for building your own methods

To organize your story into more manageable pieces To provide an object with additional behaviors

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Alice in Action with Java 45

The methods Pane

Alice in Action with Java 46

The functions Pane

Provides list of information returning messages Differentiate functions from methods

Functions return data, messages produce behavior

Type of information returned by functions

Proximity to another object Size in terms of height, width, or depth Spatial relation to another object Point of view (position and orientation in the world) Subparts

world object responds to different set of functions

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Alice in Action with Java 47

The functions Pane (continued)

Alice in Action with Java 48

Alice Tip: Positioning Objects Using Quad View

Actions performed after pressing ADD OBJECTS

Navigate the Alice Gallery Locate classes Use classes to add objects to the world

Two views: single view and quad view quad view

World window View from the top View from the right View from the front

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Alice in Action with Java 49

Alice Tip: Positioning Objects Using Quad View (continued) Techniques and Tools

Mouse is used to

approximately position objects in the scene

Camera Navigation is used to

set the camera point of view

Drop-down menu methods are used to

resize objects more precisely position objects in the scene

Quadview is used to

position one object relative to another object

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Alice in Action with Java 51

Summary

Alice: software tool used to create virtual worlds User story: prose description of program form the user’s point of view Shot: component of a scene with the camera at one viewpoint Algorithm: flow of actions that solves a problem Storyboard-sketch: drawing of a distinct screen in a computer application

Alice in Action with Java 52

Summary (continued)

Alice window: menus, buttons, object tree, details area, world window, editing area, and events area Class: blueprint for an object Method: behavior-producing message Function: message that returns information Software engineering encompasses software design, and implementation and testing

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Student To-Do

Read Chapter 1 (Adams) Complete the Alice tutorials Create your own hello world program