Introduction to Alice

Alice is named in honor of Lewis Carroll’s Alice in Wonderland

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AliceA 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)

Install the software on the CD (or downloaded)

Do a complete install

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Demo: Getting started

Starting AliceLoad and run a world

AppendixA_FirstWorld.a2w (movie) AppendixA_DancingBee.a2w (interactive)

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Kinds of Animations

Two kinds of animations:Movie

Passive user watches the animationInteractive

Active user clicks on mouse, types a key on keyboard …Actions of user are called events

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Demo: A new world

Create a new world File ! New Choose template

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Demo: Adding objects

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Techniques and ToolsMouse is used to

approximately position objects in the sceneCamera Navigation is used to

set the camera point of viewDrop-down menu methods are used to

resize objectsmore precisely position objects in the scene

Quadview is used toposition one object relative to another object

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ObjectsAn "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 performtasks it can carry out

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Object PartsObjects may be composed of parts

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3 Dimensions, 6 DirectionsA 3D object has

3 dimensionsheight, width, depth

6 degrees of freedom (directions of movement)

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Center of an object(depends on the object!)

At the center of mass

Where it stands on the ground

Where it is held

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ClassObjects are categorized into classes

Each object is an instance of the class.

Person

Dog

harry

hermione

ron

fang

fluffy

snuffles

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GalleriesClasses (3D models) are found in the galleries

Local gallery (installed with the software) CD Gallery (only if CD is in the machine) Web gallery

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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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Getting Started With Alice

The secret to getting started is quite simple:

Play!!

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Animation Programs: Scenarios and Storyboards

Alice

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Step 1: DesignDecide on the problem to be solved

Often the problem to be solved is given to you by your instructor, team leader, etc.Other times, you get to make it up!Here we will practice both (but emphasize the latter)

Design a solution We will use a storyboard designBreak down a long scenario into sequences of many short scenarios.For each (short) scenario, a story board is created to depict the sequence of scenes.This makes our task easier: short scenarios are easier to implement than long, monolithic ones

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Step 1: Design Design a solution

We will use a storyboard design technique, commonly used in the film industry

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ExampleThe scenario is:

Several snow-people are outdoors, on a snow-covered landscape. A snowman is trying to meet a snowwoman who is talking with a group of her friends (other snowwomen.) He says "Ahem" and “blinks” (widens) his eyes, trying to get her attention. The problem is:

How can we create this animation?

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Create Initial World

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StoryboardOption 1: Sketches

None

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StoryboardOption 2: Screen Shots

Initial scene Snowman tries to catch snowwoman’s attention

Snowwoman looks around

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Storyboard Option 3: Text

Animation Artists sketch their storyboardsYou may not have such expertise, so here is a textual form that can be used:

Do the following actions in order snowman turns to face snowwoman snowman calls out to the snowwoman and “blinks eyes” snowwoman turns around.

This is like a "to-do" list. The Learning to Program in Alice

textbook puts a textual storyboard in a box.

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Creating An AnimationProgram

Alice

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Step 2: Implementation

To implement the storyboard, translate the actions in the storyboard to a program.Program (a.k.a. script)

a list of instructions to have the objects perform certain actions in the animation

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Writing the ProgramOur planned storyboard (to-do list) is:

Do the following actions in order snowman turns to face snowwoman snowman calls out to the snowwoman and “blinks eyes” snowwoman turns around.

The idea now is to translate the design steps to program instructions.

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Translating the DesignSome steps in the storyboard can be written as a single instruction

The snowman turns to face the snowwomanOther steps are composite actions that require more than one instruction

The snowman tries to catch the snowwoman’s attention is two actions

The snowman says “ahem”The snowman widens his eyes

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Action Blocks in Alice

Sequential Action Block

Simultaneous Action Block

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Demo

Ch02Snowpeople

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Concepts in this first program

Program instructions may have arguments Example: for the resize instruction, the argument we used in this example was

size of the eye (multiply x 2 or 1/2)

DoTogether and DoInOrder blocks can be nested one inside the other

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TestingAn important step in creating a program is to run it – to be sure it does what you expect it to do.We recommend that you use an incremental development process:

write a few lines of code and then run it write a few more lines and run it write a few more lines and run it…

This process allows you to find any problems and fix them as you go along.

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Comments

While Alice instructions are easy to understand, a particular combination of the instructions may perform an action that is not immediately obvious. Comments are used to document the code – explain the purpose of a particular segment of the program to the human reader.

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Demo

Ch02SnowpeoplewithCommentsComments in this example world illustrate

description of the action performed by the entire method description of the purpose of a small segment of code

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