A PBD Approach to Game Development Using Geometric Reasoning: Matrixx

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A PBD Approach to Game Development Using
Geometric Reasoning Matrixx
Presented By
Karlene Williams
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Outline

• Background
• Stagecast Creator
• Related Works
• Concept Geometric Reasoning
• Programming Language Matrixx
• Programming Approach
• Language design
• Language features
• Evaluation Strategy
• Question Comments

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Background

• Objective
• To explore effectiveness of a PBD approach in
  supporting children in their construction of
  simple games.
• Domain Game development
• End Users Children 10 16, novice programmers
• Motivation
• Drawbacks of Stagecast Creator
• Move programming closer to the way children
  actually think
• Enhance childrens puzzle-solving techniques

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Stagecast Creator

• Visual programming environment for kids
• Programming by demonstration (PBD)
• Visual before-after rules
• Users create sims - interactive games or
  simulations

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Related Work

• Degrees of Comprehension Childrens
  Understanding of a Visual Programming Environment
  (Rader et al, 1997)
• single user studies with KidSim
• young and old elementary school participants
• younger participants were unable to master most
  programming concepts

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Related Work (Cont.)

• How does a visual simulation program support
  students creating science models
  (Cathy Brand et al, 1996)
• University of Colorado researchers
• Worked with 4th 5th graders to create animated
  computer models of scientific concepts covered in
  their curriculum
• Children hated rule making process of Stagecast
  creator. They suggested that improving the rule
  making process would enhance the application

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Current Work - Matrixx

• Visual programming environment for kids
• Programming by demonstration (PBD)
• Rule-Based programming
• Automatic rule generation via geometric
  reasoning!!! (based on demonstration)
• Users create interactive games or simulations

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Geometric Reasoning

• About effectively planning the motion of objects
  in geometrically complex situations (scenes)
• Discipline of Computational Geometry
• ORourke et al defines it as the study of
  algorithms for solving geometric problems on a
  computer 1
• Connected to the mathematical discipline of
  discrete and combinatorial geometry 3
• Problem difficult to formalize with uniform
  concept!!!

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Geometric Reasoning Current Work

• Martixx is an intelligent application - reasoning
  about the motions and interactions of geometric
  objects.
• Assumptions
• Exact and complete representation of the objects
  and their relative positions are available.
• Automated motion planning to some extent
• Restriction to translational motion
• Current distance (at point of PBD) from predator
  is minimum distance allowed from victim. E.g. Fish

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Geometric Reasoning Current Work

• Character motion planning problem (following
  3)
• Given a character C at some initial position ps
  and a finite collection of obstacles O. The task
  is to plan motions that will take C from ps to
  some goal position pg without colliding with any
  of the obstacles or violating any constraint
  previously demonstrated by the user.

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Creating a Game Basic Steps

• Select new game
• Enter name, grid size (pixel), level
• Select level - what terminates level?
• Drag drop background and characters on grid
  add sound effects
• Demonstrate rules of game

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New Open Levels Close Save Save As Exit
___The Interface__________
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___The Interface__________
?
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Language Design

• Abstraction

• Entire grid environment represented as an object
  that maintains state knowledge
• stores relative positions of objects as geometric
  values.
• stores info. about which grid is occupied by
  which character/object.

• Each grid is represented as an object with
• a unique ID
• status (occupied/vacant)

• Each character is represented as an object with
• unique ID
• status (selected/unselected)

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Language Design

• Control structures can be represented
• Eg. Selecting Stop At gt position and
  identifying position, generates a rule that says
• if grid layout ! (some value), Then (play
  on)
• Moves A character/object can be programmed to
  move
• one tile left, right, up or
  down as long as the tile
• is vacant
• Relative motion Used to define how a character
  (victim)
• should move in
  response to another
• characters
  (predator)

?
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Language Features

• Modes
• Play/Create
• Edit
• Preview/Test
• Preview pane that shows simulation
• of game as it is being created
• Editing user scrolls time bar to
• required spot and make changes
• Levels Games may have multiple levels

Edit
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Language Features

• Toolbox
• Environments
• Characters
• Animation
• Sounds
• Speed

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Language Features Contd.

• Event Control
• Start At
• Stop At
• (Display)

? ?
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Creating Rules - Stagecast Creator
Task Create a rule to make Bingo walk to the
right.
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Creating Rules - Matrix
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Creating Rules - Matrix
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Creating Rules Relative motion
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Creating Rules - Relative motion
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Testing Strategy

• 2 high school students to each complete one
  45-minute session
• Complete short tutorial activity to learn how to
  use Matrixx
• Complete several small programming tasks

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Evaluation Strategy

• Three techniques to be applied
• Talk Aloud Protocol
• Heuristic evaluation (system checklist - Xerox
  Corp.)
• CD analysis
• Data collection through direct observation -
  field notes, coding sheet and questionnaires
• Identify situations that might indicate glitches
  in language design

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Comments

• Difficult to formalize with uniform concept
• Collaborative learning for team development and
  Social interaction)
• Educational benefits
• Maintained critical thinking
• Higher levels evaluation, synthesis
• Higher retention

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References

• 1 J. ORourke. Computational Geometry in C.
  Cambridge University Press, Cambridge, 1994.
• 2 H. Edelsbrunner. Algorithms in Combinatorial
  Geometry. Springer, Heidelberg, 1987.
• 3 F. Schwarzer. Geometric Reasoning About
  Translational Motions. 2000. Retrieved from the
  Worl Wide Web on November 25, 2003
  http//www9.in.tum.de/publications/2000/Diss-2000-
  Schwarzer.pdf

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Questions ?
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The End