Autonomous Characters

Professor: Bill Tomlinson

Fall 2003

Tuesdays 3-5:50pm

HIB 335

Meeting 3

State of the Union

• We’ve covered the two big topics that we’ll be addressing this semester.

• Still lots of things to come, but we’ll be focusing throughout on the link between computer code and animation.

Go Over Assignments

• Any troubles getting things to compile?

• Other questions?

Go Over Readings

• Lasseter – Other approaches to animation?

Go Over Readings

• Picard/Wilson – Emotional modeling. Too simplistic?

Go Over Readings

• Burke/Tomlinson – Any questions about the system?

Go Over Readings

• Stein – any code questions?

Action Selection – Why?

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

Behavior

• Connection between stimulus and response

Learning

• Connection between an action and consequences

Behavioral change over time (over different time scales)

• Action

• Learning

• Development

• Learning

Emotional change over time

• Emotion

• Mood

• Personality

The Craft of Acting

• Making decisions appear meaningful.

• Connecting actions and emotions.

Drama

• Action selection

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

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

Action Selection – An Example

Vec3 myPos = new Vec3();

this.getPosition(myPos);

if (myPos.mag() <20)

{

SoundSystem.play(

"w:/sound/beep.wav");

}

Perception

• What can people sense?

Perception

• What can the characters sense?

Perceivable things

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

Some other things you’ll need to know about…

Conditionals

• if (something) { do this;}

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();

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.

Play a sound

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

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

Some code examples:Get position of camera

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

Some code examples:Get 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);

Some code examples:Get 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);

Assignment 3

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

Emotional assignment

happiness = .5;

OR

this.getPosition(myPos);happiness = myPos.x();

OR

…

Assignment 3

• Don’t forget comments, println.

Readings for Oct 21

• Braitenberg (handout)

• Acting - Cohen (handout)

• Vectorpark (link)

• Stein (Ch 4)