CS320n – Elements of Visual
Programming
Alice Concepts
Mike Scott
(Slides 1-2)
What We Will Do Today
• Finish the material in chapter 1
• Continue working on the tutorials and
appendix 1 material in Alice
Visual Programming
Alice Concepts
2
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”
Visual Programming
Alice Concepts
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Events
• Animations that are “interactive depend on the
user’s actions
– mouse click
– key press
– others (head mounted device, dance pad)
• Actions are events
• Interactive programs are event driven
Event window portion of Alice
Visual Programming
Alice Concepts
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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?
Visual Programming
Alice Concepts
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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
Visual Programming
Alice Concepts
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Classes
• Objects are categorized into classes
Rico
Skipper
Private
Penguins
Snoopy
Kowalski
Odie
Opus
Dogs
Ren
• Each objects is an instance of the class
• All objects in a class
– have the same properties
– generally can perform the same tasks
Visual Programming
Alice Concepts
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Objects in a Virtual World
• In Alice, each 3D model is a class of
objects
– class: penguin
– objects: penguin,
penguin1, penguin2
Visual Programming
Alice Concepts
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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
Visual Programming
Alice Concepts
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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
Visual Programming
Alice Concepts
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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 on
ground usually have
center between feet
– things that are held have
center at point object
would be held
Visual Programming
Alice Concepts
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Distance
• object’s 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
Visual Programming
Alice Concepts
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Position in the World
• The world in an Alice
program models a 3D
space
• every object in the world
has a position
x, y, z, coordinate relative
to the center of the world
• ground starts at center of
world
• axes (green = up, red =
right, blue = forward)
Visual Programming
Alice Concepts
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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
Visual Programming
Alice Concepts
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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
Visual Programming
Alice Concepts
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Alice Concepts
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Class Work
• Continue work on tutorials
• Appendix A,
– Part 1
– Part 2: Using Pop up menus to create an
initial scene.
Visual Programming
Alice Concepts
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