CS101 Lecture 16 Introduction to Alice - Computer Science › courses › cs101 › old › 2012fall...

10/22/12

1

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 on keyboard … !  Actions of user are called events

10/22/12

2

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)

4

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

10/22/12

3

5

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…

10/22/12

4


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


User Stories !  Contain !  Basic description of what happens when program

runs !  Nouns in story (Alice, the White Rabbit) correspond to

objects !  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.”

10/22/12

5


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


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

10/22/12

6


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.”


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

10/22/12

7


Programming Implementation in Alice (continued)


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

10/22/12

8


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

10/22/12

9

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

10/22/12

10

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


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

10/22/12

11

Demo: Adding objects

Galleries

!  Classes (3D models) are found in the galleries !   Local gallery (installed with the software)

!  Minimum or complete options !  Web gallery

10/22/12

12


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)

10/22/12

13


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


Accessing Object Subparts (continued)

10/22/12

14


Accessing Object Subparts (continued)


Sending Messages

!  Alice programs rely on sending messages to objects

!  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

10/22/12

15


Sending Messages (continued)


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

10/22/12

16


Testing and Debugging (continued)


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

10/22/12

17


Coding the Other Actions (continued)


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 !  object.message(value); more...

!  Control structures manage other statements !  Example: doInOrder contains other statements

10/22/12

18


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


The Final Action (continued)

10/22/12

19


Final Testing

!  First set of actions are performed separately

!  Final actions are performed simultaneously


Final Testing (continued)

10/22/12

20


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’s Details Area

!  Reflects attributes and behaviors of selected object

!  Three panes: properties, methods, and functions

10/22/12

21


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


The properties Pane (continued)

10/22/12

22


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(…)


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

10/22/12

23


The methods Pane


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

10/22/12

24


The functions Pane (continued)


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

10/22/12

25


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

10/22/12

26


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


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

10/22/12

27

Student To-Do

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

CS101 Lecture 16 Introduction to Alice - Computer Science › courses › cs101 › old › 2012fall...

Documents

Transcript of CS101 Lecture 16 Introduction to Alice - Computer Science › courses › cs101 › old › 2012fall...