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Behavior
Autonomous Characters
Self-Directed characters "puppets that pull their own strings" -Ann Marion
Autonomous Characters
AcknowledgementMuch of this material is taken from the work of Craig Reynolds. He maintains a web pages including a rich source of material of steering behavior and the consumate source on flocking.
Also see: Steering Behaviors For Autonomous Characters
by Craig Reynolds
Three-Tier Hierarchy
Action selectiongoals and strategies “What to do”
Steeringguidance / motion control “How to do it”
Locomotionmovement generation “Getting it done”
Flocks in Film
1987: Stanley and Stella in: Breaking the Ice, (short) Director: Larry Malone, Producer: Symbolics, Inc.
1988: Behave, (short) Produced and directed by Rebecca Allen
1989: The Little Death, (short) Director: Matt Elson, Producer: Symbolics, Inc.
1992: Batman Returns, (feature) Director: Tim Burton, Producer: Warner Brothers
1993: Cliffhanger, (feature) Director: Renny Harlin, Producer: Carolco.
1994: The Lion King, (feature) Director: Allers / Minkoff, Producer: Disney.
Flocks in Film
1996: From Dusk Till Dawn, (feature) Director: Robert Rodriguez, Producer: Miramax
1996: The Hunchback of Notre Dame, (feature) Director: Trousdale / Wise, Producer: Disney.
1997: Hercules, (feature) Director: Clements / Musker, Producer: Disney.
1997: Spawn, (feature) Director: Dipp₫, Producer: Disney.
1997: Starship Troopers, (feature) Director: Verhoeven, Producer: Tristar Pictures.
1998: Mulan, (feature) Director: Bancroft/Cook, Producer: Disney.
Flocks in Film
1998: Antz, (feature) Director: Darnell/Guterman/Johnson, Producer: DreamWorks/PDI.
1998: A Bugs Life, (feature) Director: Lasseter/Stanton, Producer: Disney/Pixar.
1998: The Prince of Egypt, (feature) Director: Chapman/Hickner/Wells, Producer: DreamWorks.
1999: Star Wars: Episode I--The Phantom Menace, (feature) Director: Lucas, Producer: Lucasfilm.
2000: Lord of the Rings: the Fellowship of the Ring (feature) Director: Jackson, Producer: New Line Cinema.
Seeking and Fleeing
Seeking and Fleeing Applet (Reynolds)
Pursuing and Avoiding
Pursuing and Avoiding Applet (Reynolds)
Separation: Avoid Collisions
Alignment
Flocking Demos
Flocking Applet (Craig Reynolds) Fish Schooling (Steve Hughes) Beach House (Ishihama Yoshiaki )
For more demos see Reynolds “Boids in Java”
Do People Flock?
Social psychologist’s report the people tend to travel as singles or in groups of size 2 to 5.
Characteristics of Groups
Proximity Coupled Behavior Common Purpose Relationship Between
Members
Moving Formations
Pairs: Side by side Triples: Triangular shape
Stationary Formations
Moving pair approachesstationary triple
Stationary quintuple formed
Locomotion Model for Walking
Two Parameters Speed
Combination of step length and step rate
Orientation Head direction for forward walking
Accelerate Accelerate Accelerate Turn Left No Turn Turn Right
Coast Coast Coast Turn Left No Turn Turn Right
Decelerate Decelerate Decelerate Turn Left No Turn Turn Right
Action Space
Distributed Preference Voting
Delegation of voters: Constraint Proxies Proxies vote on each cell of the action space Votes are tallied Winning cell represents best compromise among
competing interests
Vote Tabulation
1.0
Pursuit Point
Tracking
Maintain Formation
Inertia
Centering
Maintain Target
Velocity
Avoid Peds
Winning Cell
Electioneer
1.0
1.0
2.0
2.0
4.0
5.0
Avoid Obstacles
A Group of Two Following a Path
ped 1
walkway axis
pursuit point
Winning vote = Accelerate/Turn Right
ped 2
-1.0 -1.0 +1.0-1.0 -1.0 +1.0-1.0 -1.0 +1.0
Pursuit Point Tracking
+1.0 +1.0 +1.0 -1.0 -1.0 -1.0 -1.0 -1.0 -1.0
Maintain Formation
+1.0 +1.0 +3.0 -3.0 -3.0 -1.0 -3.0 -3.0 -3.0
2.01.0
Election for ped 1
Avoiding an Obstacle -- Trajectory
Small look-ahead distance Large look-ahead distance
ped 1
ped 2
walkway axis walkway axis
ped 1
ped 2
Interaction Between Pairs -- 1
Interaction Between Pairs -- 2
Interaction Between Pairs -- 3
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