Alice: A Visual Introduction to Programming

Chapter 1 Part 2

Objects Alice uses objects

o Tento Soldiero Princess

Objects perform actions

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– Turn

– Move

– Fly

– Wave

The Alice System

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Open SnowLove in Examples

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Executing Alice Program

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PLAY

Controlling Runtime Speed

Can increase speed of program Move slider of speed control

Useful when troubleshooting to skip over parts of program that work

Max of 10x normal

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The Alice Environment

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Toolbar

Object Tree

DetailsPanel

TileTile

Checkpoint

How do you control the speed of an Alice program that is being played?

What part of the Alice environment displays a view of the world?

What part of the Alice environment displays a list of objects in the world?

What is a tile?

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Objects

Anything that can be identified as unique from other things

How is an object unique?o Has a nameo Has properties

Color, opacity, etc.o Can perform actions (methods)

Associated actions (move, turn , think, etc.)

Tasks it can carry out

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Object Properties

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Object Selected

Change Properti

es

Object Selected

Opacity

How transparent an object iso Less opaque an object, more transparent

Opacity of 100%, cannot see through the object Opacity of 0%, object is completely transparent

Like clear glass

An object with opacity of 0% is invisible A partially transparent object can be

used too Make something look far away in watero Have a ghostly appearance

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Objects and Object Parts

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Objects are made of other subparts

Snowman made of:o head

topHat leftEye rightEye carrotNose mouth

o leftArmo rightArmo Bottom

Objects named in “camel Case” formato 1st letter is lower caseo Upper case next word’s 1st

letter

Methods Methods

o Set of instructions to perform task

o Default method world.my first

method

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Methods

Each object and its subparts can be manipulated with methodso Moveo Turno Rollo Say…

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The World is an Object

Contains all other objects

Also has its own propertieso Atmosphere coloro Lightingo Fog

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Checkpoint

What are properties? What is the name of a property that

o Determines an object’s color?o Allows you to see through an object?

What is a method? What do you call a part of an object

that can move by itself?

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Alice has Class(es)

Objects are created from classes

Blueprint that describes a particular “type” of object

Defines a particular kind of object

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Animals Collection

Classes Gallery - collection of different object types

(animals, beach, people, etc.). Class - each item found in the Gallery Two galleries are used

o Local gallery (stored on computer)o Web gallery (maintained by creators of Alice)

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Class Instance in Alice Class: Chicken Instance: An object that

is created from a class Examples

o Chickeno Chicken2o Chicken3

Each instance has its own properties, methods, functions

Can manipulate each one individually

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Creating a New World

• Create a new worldo File Newo Choose template

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Adding Objects

Click on Add Object

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Adding Objects: Scene Editor

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Click on People collection thumbnail

Add Coach Place

object in scene editor byo Clicking

on ito Or drag

it

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Coach Object With Bounding Box

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Saving Alice World Click on File then Save World

Has .a2w extension

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Demo: Saving a world

Writing and testing an animation is an intense load on the computing systemo Crashes can occur

Best solution Save your world every 15 minutes Also save to a backup system

Ex: USB flash drive

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Checkpoint What is a class? Are classes or objects stored in Alice

galleries? What are two ways to add an object to a

scene? What appears around an object when

selected? Where do you find an object’s properties?

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3D Objects and the Camera

Alice world and objects are three-dimensionalo Heighto Width

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– Depth – 3rd dimension

3D Movement

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Motion is based on OBJECT’s perspective…our left is the Coach’s right

Forward is perceived as the object getting larger as it gets closer to us.Backward is perceived as the object getting smaller as it gets farther away from us.

The Camera

When you create an Alice world a camera is automatically placed in the world

Displays image of world in Scene Editor windowo Called camera viewpoint

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Camera Controls

Drive forward, backward, turn left and right

Move camera up, Tilt camera up, downdown, left, right

You can make camera move faster by dragging mouse pointer away from center of camera control

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Different World Perspectives Sometimes difficult to

tell where object is in relation to other objects

Fish looks like it should be in water

Change world perspectiveo Look at fish from

perspective of water instead of sky

Also called Camera control or point of view

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Homework Read chapter 1 Do tutorials

o Tutorials 1-1, p 6o Tutorials 1-2, p. 19o Tutorials 1-3, p. 34

Due one week after assigned with 1 week grace

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