Interactive Narrative

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Interactive Narrative

• People
• Andrew Stern
• Michael Mateas, Janet Murray, .. (Georgia Tech)
• Michael Young (NC State University)
• OZ project (Loyal, ORielly)
• Sheldon Lee
• Bob Bates
• and Others

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Interactive Narrative

• What is a plot/narrative?
• Sequence of Events that has a causal
  structure
• Structure of Narrative (Mckee 1998)
• Story, Acts, Scenes, beats
• Conflict tension
• Character
• A Clock

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Interactive Narrative

• Issues in Interactive Narrative
• Agency
• Conflict (knowing users goal)
• Tension between storyteller and users
• Authoring artistic and dramatic narratives vs.
  generative mechanisms

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Interactive Narrative

• Character-based
• Based on believable characters
• Model personality, emotions
• Use planning to improvise
• e.g. Barbara Hayes Roth, Andrew Stern, OZ project
• The story emerges from interacting
• with rich compelling characters

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Interactive Narrative

• Plot-based
• Linear
• interactivity is achieved through other forms
• Non-linear
• Use branching-trees to
• represent narrative
• User choices are encoded
• in the branches

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Interactive Narrative

• Non-linear Narrative generation/authoring
• Script the tree
• Use planning to construct tree at scene load time
• Use reactive planning to dynamically construct
  tree at run-time

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Interactive Narrative

• Plan-based Interactive Narrative, sometime called
  goal-based Interactive Narrative
• StoryNode
• Goals this node will solve
• Preconditions
• PostCoditions
• Subgoals or terminal action
• Planning algorithm will cycle through these nodes
  building a tree that solves story goal

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OZ Project
Player

• Believable Agents
• Drama Managers

Presentation
Drama Manager
Character
Avatar
Character
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OZ Project

• Simple, 3D animated world
• The Woggles
• move by bouncing from place to place.
• have body language, expressing emotions by
  changing shape
• have social relationships
• engage in social behavior

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OZ Project
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OZ Project (Interaction)

• The players avatar is also a woggle
• By interacting with woggles, you find out about
  their social structure.No plot, but very
  engaging behaviors
• Personalities of woggles become quickly clear
• Threaten one, its friend intervenes to try and
  scare you off
• Join or start games of follow the leader

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OZ Project (Drama Manager)

• Authoring involves creating a dramatic arc
• Fixed in traditional fiction
• Various branching structures possible in
  interactive fiction
• How to tell a great story while giving player
  freedom?
• Complexity of possible branching in rich worlds
  quickly makes authoring unmanageable
• Usual solutions of sharply limiting world or
  player restrictive

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OZ Project (Drama Manager)

• Consider a story as a sequence of scenes
• Scene significant event/turning in the plot
• Lots of variability in how a scene plays out
• Scenes and relationships between them form a
  space of possible plots
• Relationships that must hold between scenes
  structure the space
• Some relationships inviolable e.g., establishing
  prerequisite
• Some can be varied e.g., establishing motivation
  for an action before or after the action itself

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OZ Project (Drama Manager)

• Given
• Evaluation function that rates sequences of
  scenes
• Methods for affecting the game
• Ensure
• The sequence of scenes a
• player experiences corresponds to a good
  story

Choice of next scene determined by dramatic
potential of possible futures
Where player is now
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OZ Project (Drama Manager)

• Drama Manager in effect is playing a game
• Presumably non-adversarial
• Ideally, the player doesnt know that it is there
• Moves for the Drama Manager
• Changing behavior of NPCs
• Random events in the world
• Acts of God

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Crawfords Erasmatazz

• Interactive storytelling you interact with
  characters in an authored world
• Menu-based interaction
• Player focus is on interacting with NPCs rather
  than physical actions
• Overall story scripted by author, but no drama
  manager
• Interesting part is modeling
• Moods Anger, arousal, joy, fear
• 21 personality traits (e.g., integrity, timidity,
  )

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Hayes-Roths Virtual Theater Project

• Uses AI blackboard technology as implementation
  for characters
• Simple numerical personality models
• Examples
• Kids tell stories by giving puppets high-level
  instructions
• Agents as social facilitators in shared
  environments (Erin the bartender)

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Façade

• Hybrid (goal-based/character-based Interactive
  Narrative)
• Characters operate
• under a drama
• manager

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Façade
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Mirage

• Character Development
• User Modeling
• User predicted character affects
• scene assembling
• NPC choices and actions

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Mirage