Interactive Systems

1
Interactive Systems

• Class 9

2
Creature of the week
3
Outline

• What you should know by now
• On wagging tails
• Notes on the assignment
• Some big ideas artificial life
• Moving objects in the world, timers, collision
  detection

4
What you should be able to do by now

• Rotate an object
• Co-ordinate between objects to start rotations
• Animate an avatar

5
Hints about wagging tails problem!

• You need to attach the tail to an anchor object
  which is can rotate around (like a ball and
  socket joint)
• The problem is that once you join the tail to the
  body, it no longer rotates around the ball and
  socket
• We are looking into this to find a solution and
  will let you know when we do.
• In the mean time if you want to keep working,
  look into llSetLinkPrimitiveParams(tail_number,
  PRIM_ROTATION, r)

6
Notes on the assignment

• Remember you will be peer reviewing each other's
  pets next week in the labs. This means two
  things
• You have to have a pet ready to be reviewed. It
  does NOT need to be finished, but it should be a
  work in progress
• You must attend the labs in weeks 10 /11to take
  part in the peer review, or miss 25 of your
  assignment mark.
• 1st year Fri 21st Nov 3.15 5.15pm
• 2nd year Tues 25th Nov 2.15 4.15pm

7
A tip

• For the assignment, you are expected to do
  something more than write a couple of lines of
  code within a function or event.
• You should be working on a more complex program
  putting the bits and pieces you have learned in
  lab class into a coherent whole
• If this sounds hard, discuss it with the lab
  helper this week

8
Interactive behaviour of the pet

• 40 49. Poor. Pet has major bugs, or is
  extremely derivative. Limited scripting skills
  demonstrated (e.g. just basic text output)
• 50 59 Adequate. Pet has at least one
  interactive behaviour. It demonstrates that
  basic scripting skills have been learned and used
  to respond to user input (typed text, or button
  clicking). Output could be text, sounds or
  animations.

9
Interactive behaviour of the pet

• 60 69 Good. Pet demonstrates a couple of
  interesting behaviours. It can respond to the
  surroundings and other creatures as well as the
  user.
• 70 Excellent. Exhibit demonstrates a complex
  behaviour which requires more advanced scripting.
  For example, it could execute a sequence of
  behaviour under script control, or behave as a
  member of a flock.

10
Artificial Life

• Artificial life (commonly Alife or alife) is a
  field of study and an associated art form which
  examine systems related to life, its processes,
  and its evolution through simulations using
  computer models, robotics, and biochemistry.1
  Wikipedia
• Strong alife "life is a process which can be
  abstracted away from any particular medium" John
  von Neumann
• What do you think about this?

11
Artificial Life

• (the) law of uphill analysis and downhill
  synthesis'' applies... it's easier to design a
  mechanism from scratch to do something, than to
  figure out just how nature has contrived to do
  it this suggests that maybe the natural way
  isn't really insuperably complicated. Cosma
  Shalizi

12
Braitenburgs Vehicles

• An example of behaviour based robotics
• See http//www.amazon.co.uk/gp/reader/0262521121/
  refsib_dp_pt/277-3507346-2749668reader-page
• A creature which is afraid of the light
• More light produces faster movement.
• Less light produces slower movement.
• Darkness produces standstill.

13
Braitenburgs Vehicles - example

• This run has three vehicles, each of a different
  type, and two lamps. Green is the obsessive one.
  She singlemindedly and frenetically searches for
  and attempts to ram the nearest and brightest
  light source, and has no regard for anything else
  (behaving like Braitenberg's Vehicle 2b). Blue
  has more self-control and more intelligence. She
  likes to find a cozy spot near a lamp and settle
  down, but she will flee if a predator comes too
  close. Red is the predator Light doesn't
  interest her, only the movement of possible
  prey.
• http//people.cs.uchicago.edu/wiseman/vehicles/an
  imation-1.mov

14
Boids

• An algorithm used for simulating flocking
  behaviour
• Used in games and 3D animations
• http//www.red3d.com/cwr/boids/
• Complexity emerges from 3 simple rules
• Separation steer to avoid crowding local
  flockmates
• Alignment steer towards the average heading of
  local flockmates
• Cohesion steer to move toward the average
  position of local flockmates

15
Scripting you will learn today

• Cookie monster gets hungry again after a bit
• Cookie monster grazes for food
• Cookie monster side-steps round obstacles
• Cookie monster mummy and daddy make babies

16
Delaying hunger pangs

• How would you stop the monster getting hungry as
  soon as he has eaten?

17
Delaying hunger pangs

• integer hungry 0
• timer()
• llOwnerSay("Getting hungry again")
• hungry 1
• eat()
• llOwnerSay("I found a cookie")
• llSay(42, "eaten")
• hungry 0
• llOwnerSay("Burp. Not hungry anymore")
• //set a timer so he doesn't get hungry
  for 30 seconds
• llSetTimerEvent(15.0)

18
How would you make the cookie monster graze?

• Monster will sense a cookie and move towards it.
  When close enough he will eat it.
• Need to use sensor, llTarget and llMoveToTarget

19
Grazing solution part 1

• moveToCookie(vector cookiePos)
• llSetStatus(STATUS_PHYSICS, TRUE)
• llSetStatus(STATUS_ROTATE_X STATUS_ROTATE_Y
  STATUS_ROTATE_Z, FALSE)
• // Ask to be informed when were 0.5 metres
  from cookie
• targetID llTarget(cookiePos, 0.5 )
• //start moving to cookie
• llMoveToTarget(cookiePos, 0.9)

20
Grazing solution part 2

• sensor(integer num)
• vector targetPos
• targetPos llDetectedPos(0) lt1.0, 0.0,
  0.0gt
• if (hungry)
• moveToCookie(targetPos)
• else
• llOwnerSay("Quietly digesting")

21
Grazing solution part 3

• at_target( integer number, vector targetpos,
  vector ourpos )
• llOwnerSay("We've arrived!")
• eat()
• // Stop moving towards the destination
• llStopMoveToTarget()
• // Stop notifications of being there or
  not
• llTargetRemove(targetID)
• // Become non-physical
• llSetStatus(STATUS_PHYSICS, FALSE)

22
Side step to avoid obstacles

• //we have detected that we have collided, so
  move out of the way
• collision(integer num_detected)
• llOwnerSay("Oi!")
• vector pos llGetPos() lt0.0, 2.0, 0.0gt
• llSetStatus(STATUS_PHYSICS, TRUE)
• llMoveToTarget(pos, 0.2)

23
Mating behaviour

• //we have detected that we have collided, so
  move out of the way
• collision(integer num_detected)
• if (llDetectedName(0) "CookieMonsterGreen")
  
• breed("green")
• else
• llOwnerSay("Oi!")
• vector pos llGetPos() lt0.0, 2.0, 0.0gt
• llSetStatus(STATUS_PHYSICS, TRUE)
• llMoveToTarget(pos, 0.2)

24
Mating behaviour

• //called under collision detection with another
  monster
• breed(string name)
• offset lt0.5, 0.0, 0.0gt
• vector velocity lt0.0, 0.0, 0.0gt
• llOwnerSay("Well, hey there gorgeous")
• if (name "green")
• llRezObject("babycookiemonster",
  llGetPos() offset, velocity, ZERO_ROTATION, 1)

25
Mating behaviour (attached to baby)

• on_rez(integer startParam)
• birth(startParam)
• birth(integer colour)
• //mum was blue, dad was green, I should be cyan
• if (colour 1)
• llSetColor(lt0.0, 1.0, 1.0gt, ALL_SIDES)
• llSetLinkColor(LINK_SET, lt0.0, 1.0, 1.0gt,
  ALL_SIDES)

26
Homework

• Work on your pet so you have something to show
  your reviewers next week
• Finish off previous lab exercises (this will give
  you practice at writing the kinds of scripts you
  need for your pets)