Alice: A Visual Introduction to Programming Chapter 1 Part 2.
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Transcript of Alice: A Visual Introduction to Programming Chapter 1 Part 2.
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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