Autonomous Characters

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Autonomous Characters

• Professor Bill Tomlinson
• Fall 2003
• Tuesdays 3-550pm
• HIB 335
• Meeting 3

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State of the Union

• Weve covered the two big topics that well be
  addressing this semester.
• Still lots of things to come, but well be
  focusing throughout on the link between computer
  code and animation.

3
Go Over Assignments

• Any troubles getting things to compile?
• Other questions?

4
Go Over Readings

• Lasseter Other approaches to animation?

5
Go Over Readings

• Picard/Wilson Emotional modeling. Too
  simplistic?

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Go Over Readings

• Burke/Tomlinson Any questions about the system?

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Go Over Readings

• Stein any code questions?

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Action Selection Why?

• Make a list of reasons that animate entities need
  to choose different actions

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Behavior

• Connection between stimulus and response

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Learning

• Connection between an action and consequences

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Behavioral change over time (over different time
scales)

• Action
• Learning
• Development
• Learning

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Emotional change over time

• Emotion
• Mood
• Personality

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The Craft of Acting

• Making decisions appear meaningful.
• Connecting actions and emotions.

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Drama

• Action selection
• Showcasing that action selection staging,
  lighting, responses from other actors, etc.

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Action Selection How?

• Once we decide what we want it to do, how do we
  code that?
• Finite State Machine Make a graph
• Behavior-Based AI layered behaviors Make a
  tree

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Action Selection An Example

• Vec3 myPos new Vec3()
• this.getPosition(myPos)
• if (myPos.mag() lt20)
• SoundSystem.play(
• "w/sound/beep.wav")

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Perception

• What can people sense?

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Perception

• What can the characters sense?

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Perceivable things

• Come up with a list of environmental things that
  might provoke emotional change.

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Some other things youll need to know about
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Conditionals

• if (something) do this

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Vectors

• Vec3, in particular
• Similar to a point, but more active.
• Represents what you have to do to one point in
  order to change it into another point.
• Vec3.add(a, b, c)
• Vec3.sub(a, b, c)
• thisVec3.mag()

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Navigation

• navSys.goTo(camPos)
• Will walk emotively
• sets action when .goTo is called, so be careful
  not to replace it with some other action later.

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Play a sound

• SoundSystem.play("w/sound/beep.wav")

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Rules on copying code

• Cut and paste reuse is fine with me, as long as
  you understand what the code is doing.
• Please put comments in your code to show me that
  you understand.
• Black-box behavior

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Some code examplesGet position of camera

• public Vec3 camPos new Vec3()
• camPos.setValue(CameraSystem.getPosition())
• System.out.println(CamPos is camPos)

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Some code examplesGet position of other
character

• Vec3 friendsPos new Vec3()
• research.World.getWorld().getCreature(
• "PersonACE_01 number 0").getPosition(friendsPos)
• System.out.println("PersonACE_01 number 0's pos
  " friendsPos)

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Some code examplesGet distance from me to other
character

• Vec3 distanceBetweenUsVec new Vec3()
• Vec3.sub(myPos, friendsPos, distanceBetweenUsVec)
  
• double distanceBetweenUsDouble
  distanceBetweenUsVec.mag()
• System.out.println(Distance between us is
  distanceBetweenUsDouble)

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Assignment 3

• Program character to have an emotional response
  to its environment. Attach emotional change to
  some perceivable phenomenon.

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Emotional assignment

• happiness .5
• OR
• this.getPosition(myPos)
• happiness myPos.x()
• OR

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Assignment 3

• Dont forget comments, println.

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Readings for Oct 21

• Braitenberg (handout)
• Acting - Cohen (handout)
• Vectorpark (link)
• Stein (Ch 4)