Introducing Alice to a Squeak Wonderland

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Introducing Alice to aSqueak Wonderland
Jeff Pierce Georgia Institute of
Technology jpierce_at_cc.gatech.edu
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Outline

• About Alice Squeak Alice
• Building An Alice World
• Some Lessons Learned
• Advanced Functionality

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What Alice Is...

• Allows novices to write scripts that control
  interactive 3D graphics
• Novices
• 19 year old (non-engineering) college
  undergraduates
• Like 3D LOGO
• with threads

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Alice is Not...

• Modeler / CAD Package
• Keyframing
• Multimedia Authoring
• VRML Authoring

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What Is Alice For?

• Animated Illustrations
• Games
• Small Virtual Worlds
• Rapid Prototyping
• Teaching
• Question really is What is 3D graphics for?

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Alice Squeak Alice

• Alice
• Developed by Stage 3 Research group, Randy Pausch
  director, at UVA and CMU
• Squeak Alice
• Port of Alice to Squeak
• Draws on the lessons learned, some differences in
  functionality

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Wonderland
Wonderland Camera Morph
Some generic work space
Wonderland Editor
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Squeak Alice Architecture
User Scripts
Morphic Interface
Wonderland Classes(Actors, Animations, Cameras,
Scheduler, etc.)
Database/Matrix Services
Balloon 3D (Immediate Mode)
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Key Squeak Alice Classes

• Wonderland
• Encapsulates a 3D world
• WonderlandActor
• Encapsulates behaviors for actors
• WonderlandCamera
• Responsible for drawing the world
• Scheduler
• Responsible for making time pass

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Some UML
manages
WonderlandEditor
WonderlandUndoStack
UndoActions
0..1
0..
parent
child
Wonderland
Hierarchical
WonderlandActor
0..
name
Scheduler
WonderlandScene
B3DPrimitiveEngine
WonderlandCamera
1..
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Scheduler Main Loop
DO Forever Process Any Input Events FOR Each
Scheduled Animation DO Update Affected
Objects FOR Each Camera DO Render the Updated
World
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Design Philosophy

• Focus on Behavior Specification
• Observe the 90/10 Rule
• All Tradeoffs in Favor of the Novice
• Let the Tutorial Drive the Design

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Outline

• About Alice Squeak Alice
• Building An Alice World
• Some Lessons Learned
• Advanced Functionality

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The Process

• (1) Create Models
• Objects created in external CAD Packages
• (2) Paint Textures on Models
• Unfolding and (U,V) coordinate mapping
• Good tools somewhat rare on PC
• (3) Scripting

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Making and Running Scripts

• Define behaviors
• Launch behaviors
• As program runs evaluate new code
• Script window
• GUI tools
• Direct manipulation
• Undo when necessary

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User Observation

• N gt 120
• Two Person Talk Aloud Protocol
• eavesdropping
• Critical Incident Reporting
• exit interviews after extended use

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Demo
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Starting With Wonderland

• Wonderland new
• (In Squeak, from FileList, open a model .mdl
  file)
• Opens a WonderlandCameraMorph and Wonderland
  Editor
• Within editor
• w is the current Wonderland
• camera is the current camera
• cameraWindow is the cameras window

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Filling a Wonderland

• Wonderlands understand 3D Design Studio and VRML
• w makeActorFromVRML blah.vrml
• w makeActorFrom3DS blah.3ds
• But quality tends to be low. Best
• w makeActorFrom blah.mdl

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Working with the Camera

• camera move back distance 3
• camera turn left
• cameraWindow showCameraControls
• w makeCamera

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Outline

• About Alice Squeak Alice
• Building An Alice World
• Some Lessons Learned
• Advanced Functionality

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• First, a disclaimer...

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You (and I) are not our users...
99 My Users
1 You Are Here
99 Our Users
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You (and I) are not our users...
99 My Users
1 You Are Here
99 Our Users
... kids are
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XYZ Considered Harmful
Avoid Small CognitiveHit on Every Operation
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Vocabulary Matters

• X, Y, Z ? Left, Up, Forward
• Translate ? Move
• Rotate ? Turn
• Scale ? Resize
• Depth ? FrontToBack
• RGB Triples ? Color names
• (0, 0, 255) ? blue

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Controlled ExposureTo Power Animation

• Extend, Dont Abandon Knowledge
• Optional Keywords
• Allow combinations when possible
• Distance Speed x Time
• Duration
• Speed
• Style (interpolation function)

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Animation Examples

• bunny move up
• bunny move up distance 1
• bunny move up distance 1 duration 5
• bunny move up distance 1 speed 2
• bunny move up speed 2
• bunny move up speed 2 for 5
• bunny move up distance 1 style abruptly

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All Actors Are Reference Frames

• Controlled Exposure To Power
• Optional asSeenBy keywordbunny move forward
  distance 1bunny move forward distance 1
  asSeenBy camera

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Turning at Speed

• bunny turn left speed 2
• Units?

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N50
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N50
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Turn

• There are only two kinds of turning
• bunny turn left turns 1
• bunny turn right turns 1
• bunny turn forward turns 1
• bunny turn back turns 1

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Roll Is

• Invisible to 70 of Subjects
• bunny roll left turns 1
• bunny roll right turns 1

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Scale (Resize)

• bunny resize 0.5
• Scale is a terrible term
• Many traditional APIs
• Matrix Scale Scaled Space
• Alice
• Keeps separate position/orientation and scale
  matrices. A meter is always a meter.

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Parts

• First-Class and Part properties
• Distinct from Parent-Child relationship
• Boundaries in the scene graph

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More About Parts

• Picking
• Property setting (color)
• Delete

Table
Ball
Legs (parts)
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More About Parts

• Picking
• Property setting (color)
• Delete

Table
Ball
Legs (parts)
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Pulling Objects Apart

• Is it still a part?

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Numbers Matter

• Importance of 0 and 1
• Users often try 1 when they need a number
• Alice uses 0..1 for all bounded ranges
• Novices do not understand magic ranges (0..255,
  0..32767)
• 1/4 0.25, not 0
• We changed integer division in Python
• Not a problem in Squeak

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Undo

• Make what if cost-free
• Animates
• Users are insensitive to duration
• Users are sometimes sensitive to path
• Some operations tricky
• start an animation, then UNDO

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Problems With Scripting

• Case sensitivity (85)
• Bunny and bunny the same for novices
• We made Python case insensitive
• This is problematic for Squeak
• Typing (63)
• Syntax (45)
• parentheses, dots, commas

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Novices Want End-to-End
3D Paint Tool by Dennis Cosgrove
Teddy by Takeo Igarashi
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Constructing New Objects

• Can use Pooh (demo)
• Can construct from pieces
• makeActor
• makeActorNamed
• makePlaneNamed

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Outline

• About Alice Squeak Alice
• Building An Alice World
• Some Lessons Learned
• Advanced Functionality

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Some Higher Level Commands

• bunny pointAt toySoldier
• bunny alignWith toySoldier
• bunny place onTopOf
• object toySoldier
• bunny standUp
• bunny destroy 2
• bunny resizeLikeRubber dimension topToBottom

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Animations Are Objects

• spin bunny turn left turns 1
• spin pause
• spin resume
• spin stop
• spin start
• spin loop 2
• spin loop
• spin stopLooping

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Composing Animations

• jump bunny move up distance 1.
• fall bunny move down distance 1.
• hop w doInOrder jump. fall.
• hop start
• spinJump w doTogether hop. bunny turn
  left turns 1.
• spinJump loop

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Adding Responses

• newReaction
• bunny respondWith event bunny turn
  left turns 1 to leftMouseClick
• bunny addResponse event bunny move up
  distance 2 to leftMouseClick
• bunny removeResponse newReaction to
  leftMouseClick

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Animating Morphs

• cameraWindow move right distance 100
• cameraWindow move right distance 500 duration
  4
• w getEditor move left distance 200
• cameraWindow sendToFront
• cameraWindow sendToBack

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Blending 2D and 3D

• Initial scene
• camera turnBackgroundOff
• ground hide
• Compose with 2D

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Screen vs. Scene Points

• bunny head pointAt camera duration eachFrame.
• bunny head doEachFrame bunny head pointAt
  (camera transformScreenPointToScenePoint (Sensor
  mousePoint) using bunny) duration rightNow .

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Around and Around
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Using Alarms

• myAlarm Alarm do bunny turn left turns 1
  in 5 inScheduler scheduler
• scheduler getTime

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Getting rid of the editor

• In workspace
• w Wonderland new.
• w getEditor hide.
• w makeActorFrom 'vehicles\ArmyCopter.mdl'.
• (w getNamespace at 'armyCopter') rotor turn
  left turns 5.

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Availability

• Squeak Alice
• Runs on anything Squeak does
• Free
• http//www.squeak.org
• Alice
• Runs on Windows 95 / 98 / 2000 / NT / XP
• Free
• http//www.alice.org

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Introducing Alice to aSqueak Wonderland
Jeff Pierce Georgia Institute of
Technology jpierce_at_cc.gatech.edu