CS320n

1
CS320n Elements of Visual Programming

• Alice Concepts
• Mike Scott
• (Slides 1-2)

2
What We Will Do Today

• Finish the material in chapter 1
• Continue working on the tutorials and appendix 1
  material in Alice

3
Types of Animation

• Two kinds of Alice animations
• Movie
• User watches animation
• machine-centric
• Interactive
• User participates clicks mouse,controls
  actions with keys
• user centric

4
Events

• Animations that are interactive depend on the
  users actions
• mouse click
• key press
• others (head mounted device, dance pad)
• Actions are events
• Interactive programs are event driven

Event window portion of Alice
5
Interactivity in Alice

• Animation with no interaction
• Movie
• DEMO Octopus Ride
• Animation with interaction
• DEMO Ice Skater
• What are the events?
• What response does the skater make to each
  event?

6
Objects

• What is an object?
• anything that can uniquely identified from other
  things
• What makes an object unique?
• has a name
• has properties
• width, height, color, location, age, id
• has a purpose
• associated actions it can perform
• tasks it can carry out things it knows how to do

7
Classes

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

Rico
Skipper
Penguins
Private
Snoopy
Kowalski
Dogs
Odie
Opus
Ren
8
Objects in a Virtual World

• In Alice, each 3D model is a class of objects
• class penguin
• objects penguin, penguin1, penguin2

9
Changing Properties of Obejcts

• Properties of Object can be changed
• Location can be changed by clicking and moving
  object
• Orientation can be changed in the Add Objects
  View
• Other properties, such as color, can be changed
  in the properties window when the object is
  selected

10
Object Parts

• Objects may be composed of parts
• which may in turn be composed of parts
• the whole object may be told to do something or
  an individual part

11
Center of an Object

• each object has center point
• usually near center of mass, but really set by
  graphic artist that created object
• spin point for object
• things that sit or stand onground usually
  havecenter between feet
• things that are held havecenter at point object
  would be held

12
Distance

• objects distance from each other are based on
  the distance between their center points
• may look like objects are zero distance away, but
  actually centers still some positive distance away

13
Position in the World

• The world in an Alice program models a 3D space
• every object in the world has a positionx, y, z,
  coordinate relative to the center of the world
• ground starts at center of world
• axes (green up, red right, blue forward)

14
Adding 3D Text

• Under the Add Objects window
• Creates a 3D Text Object that can be positioned
  in the scene
• Like other objects it has a host of behaviors and
  properties

15
Adding Billboards

• Billboards are flat, 2D images in a scene
• Almost any graphic type can be added.
• GIF, JPG, TIF, PNG, BMP
• Select file and image is added to scene
• Images must be created is some other program

16
(No Transcript)
17
Class Work

• Continue work on tutorials
• Appendix A,
• Part 1
• Part 2 Using Pop up menus to create an initial
  scene.