Enemy AI

1
Enemy AI

• CIS 487/587
• Bruce R. Maxim
• UM-Dearborn

2
Slides based on theCode from Advanced 3DGame
Programmingby Kenneth Finney
3
Stationary Guard - 1

• Requirements
• Visually detects potential threats
• Determines friend or foe
• Determines threat level
• Scans assigned area
• Engages hostile players
• Detects when being engaged by hostile players

4
Stationary Guard - 2

• Attributes
• Maximum vision range
• (differs for each guard)
• Minimum vision range
• (guaranteed detection distance)
• Alertness
• (some are better and some are worse)
• Attention level
• (gets worse with no activity)
• Aggressiveness
• (not always the same for each guard)

5
AIDropPoints

• Execute the fps.starter demo and open the World
  Creator Interface
• On lower right side, drill down and click on
  MissionObjects/System/SimGroup
• Call the object AIDropPoints and switch to the
  World Editor Inspector (F3)
• Make AIDropPoints an instant group using the Alt
  key and left mouse button

6
Guard

• Switch to the World Creator (F4)
• On lower right side, drill down and click on
  MissionObjects/System/SimGroup
• Call the object Guard and switch to the World
  Editor Inspector (F3)
• Make Guard an instant group using the Alt key and
  left mouse button

7
SpawnSphere - 1

• Exit the Mission Editor (F11) and enter camera
  fly mode (F8)
• Find a good location for an AI character and
  place it 20 feet off the terrain
• Switch back to the Mission Editor (F11) and enter
  World Creator (F4)
• Drill down to Shapes/Misc on lower right and
  click on SpawnSphereMarker
• Place at least two more in the world

8
SpawnSphere - 2

• Switch to World Editor Inspector (F3)
• Select all 3 SpawnSpheres in upper left (Ctrl and
  left mouse click)
• Click on expand all
• Changes the radius field to 10 and press Apply
  button

9
SpawnSphere - 3

• Select all 3 SpawnSpheres in upper left (Ctrl and
  left mouse click)
• Add the following dynamic field and values to
  each
• aggression 100
• range 100
• attention 100
• alertness 100
• Save the mission and exit to the desktop

10
Code Modifications

• Add this line to the server\script\game.cs
  function onServerCreated
• exec(./aiGuard.cs)
• At the end of the startGame() function in the
  same game.cs file add this line to start the bot
  placement process
• Schedule(3000, 0, CreateBots)
• Save game.cs and copy the file aiGuard.cs to the
  server\script folder

11
checkForThreat

• function AIGuardDBcheckForThreat(this,obj)
• DebugPrint( "this"_at_this_at_"AIGuardDBcheckFor
  Threat (from"_at_obj_at_")", "checkForThreat")
• if(!isObject(obj))
• return
• // modified to
  allow firing
• idx obj.getClosestEnemy()
• if (idx lt 0)
• return 0
• target ClientGroup.getObject( idx )

12
checkForThreat

• if ( !obj.CheckArcOfSight(target.player) )
• testRange obj.range / 2
• else
• return
• if ( obj.GetTargetRange(target.player) lt
  testRange)
• return target.player
• DebugPrint( "no threat (from"_at_obj_at_")",
  "checkForThreat")
• return 0

13
Testing Guard AI

• When the player avatar gets close enough for the
  Guard to see it, the player will be attacked
  until killed or the player moves out of range
• The Player is not able to inflict any damage on
  the Guard (a definite need in real game)

14
PathedAI

• The fps.starter contains the script
  server\scripts\aiPlayer.cs
• Add the following to the end of aiPlayer.cs
• function InsertPathedAI()
• player AIPlayerspawnOnPath("Follower","Missi
  onGroup/Paths/PathB")
• player.mountImage(CrossbowImage,0)
• player.setInventory(CrossbowAmmo,1000)
• player.followPath("MissionGroup/Paths/PathB",-1
  )

15
Path Definition - 1

• Find a relatively flat area where it will be
  easier to create a path and hit F11 to open the
  Mission Editor and switch to "World Editor
  Creator" mode.
• Expand the tree in the lower right half of the
  screen by clicking the "Mission Objects" entry.
  Expand it out like so
• "Mission Objects-gtMission"

16
Path Definition - 2

• In the "Mission" directory, you should see
  several entries to choose from.
• Click the entry labeled "Path" just once to
  create a new Path object. Name the Path object,
  PathB".
• In the "MissionGroup" tree, which is in the upper
  right hand side of the editor, expand out the
  tree and find the node labeled "PathB".

17
Path Definition - 3

• Make this node the current selection by holding
  down the "Alt" key while clicking it with the
  mouse.
• If done correctly, the selection color of the
  "PathB" entry should change from white to gray.
  Make sure the path markers get grouped under our
  new Path object.
• Return to the tree control in the lower right
  hand corner and click the PathMarker in the
  "Mission" directory.

18
Path Definition - 4

• Name the new PathMarker, wp1" and check to make
  sure it was correctly grouped under "PathB" in
  the "MissionGroup" tree control.
• Repeat the process to create two more PathMarkers
  called, wp2, and wp3".
• Make sure to place them far enough apart so you
  can see your bot run around.
• Save the mission file and exit to the desktop

19
Test PathedAI

• Run the test application again.
• Move the player avatar to a location near the
  path defined by PathB
• Open the console and type
• InsertPathedAI( )
• Close the console window and watch it go

20
PathedAIShooter

• Define another path called PathA
• Insert the following line of code in the
  aiPlayeraimAt function
• this.setAimLocation(object.getPosition())
• after the line
• this.setAimObject(object)
• You will also need to add the function
  InsertPathedAIShooter to the file aiPlayer.cs

21
InsertPathedAIShooter - 1

• function InsertPathedAIShooter()
• player AIPlayerspawnOnPath("Shooter","Miss
  ionGroup/Paths/PathA")
• player.mountImage(CrossbowImage,0)
• player.setInventory(CrossbowAmmo,1000)
• 
  // Maxim added code
• player.followPath("MissionGroup/Paths/PathA",-
  1)
• player.pushTask("playThread(0,\"celwave\")")
• player.pushTask("followPath(\"MissionGroup/Pat
  hs/PathA\")")
• player.pushTask("aimAt(\"MissionGroup/target\"
  )")
• player.pushTask("wait(10)")

22
InsertPathedAIShooter - 2

• player.pushTask("fire(true)")
• player.pushTask("wait(1)")
• player.pushTask("fire(false)")
• player.pushTask("wait(10)")
• player.pushTask("fire(true)")
• player.pushTask("wait(1)")
• player.pushTask("fire(false)")
• player.pushTask("playThread(0,\"celwave\")")
• player.pushTask("done()")

23
Testing Shooter

• Open the World Creator and place a logo some
  where near PathA
• Label the logo Target and save the mission
• Start demo and open the console window
• Type the following to test the shooter once the
  player avatar can view PathA
• InsertPathedAIShooter( )

24
Combining Them

• It is possible to have a moving enemy that also
  shoots at you
• I have not finished my version yet, but you might
  try looking at the AI Guard Unit on the Torque
  web site (this will require recompiling Torque to
  add a new class)
• Finneys version does not require recompilation
  of Torque

25
Chasing

• Add the following code where setAimObject is
  called
• if (theRole ! Guard)
• obj.setMoveSpeed(MAX_CHASER_SPEED)
• obj.setMoveDestination(tgtPlayer.getPosition(
  ))
• obj.nextBlockCheck
• this.schedule(MAX_SCAN_GAP2),
  unblock, obj)

26
Unblock

• // used to help AI when they get stuck
• function AIGuardDBunblock(this,obj)
• if (!isObject(obj))
• return
• cancel(obj.nextBlockCheck)
• this.setRandomDestinatioin(obj)