04/19/23 1

Enemy AI

CIS 487/587

Bruce R. Maxim

UM-Dearborn

04/19/23 2

Slides based on theCode from Advanced 3D

Game Programmingby Kenneth Finney

04/19/23 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

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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)

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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

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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

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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

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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

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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

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Code Modifications

• Add this line to the server\script\game.cs function onServerCreatedexec(“./aiGuard.cs”);

• At the end of the startGame() function in the same game.cs file add this line to start the bot placement processSchedule(3000, 0, “CreateBots”);

• Save game.cs and copy the file aiGuard.cs to the server\script folder

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checkForThreat

function AIGuardDB::checkForThreat(%this,%obj)

{

DebugPrint( "%this:"@%this@"~AIGuardDB::checkForThreat (from:"@%obj@")", "checkForThreat");

if(!isObject(%obj))

return;

// modified to allow firing

%idx = %obj.getClosestEnemy();

if (%idx < 0)

return 0;

%target = ClientGroup.getObject( %idx );

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checkForThreat

if ( !%obj.CheckArcOfSight(%target.player) )

%testRange = %obj.range / 2;

else

return;

if ( %obj.GetTargetRange(%target.player) < %testRange)

{

return %target.player;

}

DebugPrint( "no threat (from:"@%obj@")", "checkForThreat");

return 0;

}

04/19/23 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)

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PathedAI

• The fps.starter contains the script server\scripts\aiPlayer.cs

• Add the following to the end of aiPlayer.csfunction InsertPathedAI()

{

%player = AIPlayer::spawnOnPath("Follower","MissionGroup/Paths/PathB");

%player.mountImage(CrossbowImage,0);

%player.setInventory(CrossbowAmmo,1000);

%player.followPath("MissionGroup/Paths/PathB",-1);

}

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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->Mission"

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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".

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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.

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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

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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

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PathedAIShooter

• Define another path called PathA• Insert the following line of code in the aiPlayer::aimAt 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

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InsertPathedAIShooter - 1

function InsertPathedAIShooter()

{

%player = AIPlayer::spawnOnPath("Shooter","MissionGroup/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/Paths/PathA\")");

%player.pushTask("aimAt(\"MissionGroup/target\")");

%player.pushTask("wait(10)");

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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()");

}

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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 PathAInsertPathedAIShooter( );

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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)

• Finney’s version does not require recompilation of Torque

04/19/23 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_GAP*2), “unblock”, %obj);

}

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Unblock

// used to help AI when they get stuck

function AIGuardDB::unblock(%this,obj)

{

if (!isObject(%obj))

return;

cancel(%obj.nextBlockCheck);

%this.setRandomDestinatioin(%obj);

}