Activating and Fixing AI In Coop Games

Introduction

Howdy!

This article is an updated version of the previous tutorial Activating AI In Coop Games. Though the previous article allowed you to enable AI in multiplayer games, humanoid NPCs like Combine Soldiers could not attack the player. It is annoying, isn't it? Well, I think this is time to get over it!

Before we go on, I would like to thank Garry Newman, BunkMug & FoxFire - for their contributions to the A.I problem - and some other people on the forums who helped me to figure out that crazy stuff. I hope the article will help!

The Relationship Table

Creating the Table

First of all, we should define the NPCs relationship table. Open the BaseEntity.h file, then in the enum Class_T definition, after the #elif defined( CSTRIKE_DLL ) block, add this:

//***THOMAS*** INITS NPCs' RELATION SHIP TABLE FOR HL2DM
#elif defined ( HL2MP_DLL || HL2MP )
// For CLASSIFY
enum Class_T
{
	CLASS_NONE=0,				
	CLASS_PLAYER,			
	CLASS_PLAYER_ALLY,
	CLASS_PLAYER_ALLY_VITAL,
	CLASS_ANTLION,
	CLASS_BARNACLE,
	CLASS_BULLSEYE,
	CLASS_CITIZEN_PASSIVE,	
	CLASS_CITIZEN_REBEL,
	CLASS_COMBINE,
	CLASS_COMBINE_GUNSHIP,
	CLASS_CONSCRIPT,
	CLASS_HEADCRAB,
	CLASS_MANHACK,
	CLASS_METROPOLICE,		
	CLASS_MILITARY,		
	CLASS_SCANNER,		
	CLASS_STALKER,		
	CLASS_VORTIGAUNT,
	CLASS_ZOMBIE,
	CLASS_PROTOSNIPER,
	CLASS_MISSILE,
	CLASS_FLARE,
	CLASS_EARTH_FAUNA,

	NUM_AI_CLASSES
};
//***

Loading the Table

All right! Now we have to tell the Game Rules to use this relationship table when we start a HL2DM game. Open the hl2mp_gamerules.h file. Under the public: tab, add this:

//***THOMAS*** INITS NPCs' RELATION SHIP TABLE FOR HL2DM
#ifndef CLIENT_DLL 
void InitDefaultAIRelationships( void );
#endif
//***

Now open the hl2mp_gamerules.cpp file. Then, at the very bottom of the file, add this piece of code:

//------------------------------------------------------------------------------
// Purpose : Initialize all default class relationships
// Input   :
// Output  :
//------------------------------------------------------------------------------
//***THOMAS*** INITS NPCs' RELATION SHIP TABLE FOR HL2DM
#ifndef CLIENT_DLL 
void CHL2MPRules::InitDefaultAIRelationships( void )
{
	//Copy contents of the hl2_gamerules InitDefaultAIRelationships to here
}
#endif
//***

Let's finish by adding this in the CHL2MPRules::CHL2MPRules() function:

//***THOMAS*** INITS NPCs' RELATION SHIP TABLE FOR HL2DM
InitDefaultAIRelationships();
//***

Making Humanoid NPCs Shoot

Weapons Animations Code

First, find each weapon SP code ( located in the \dlls\hl2_dll\ folder ), then move all the animations declarations located in the SP-acttable_t function to the HL2MP-acttable_t structure. See example bellow:

acttable_t	CWeaponSMG1::m_acttable[] = 
		{
			//HL2DM ANIMATIONS LIST START
			{ ACT_HL2MP_IDLE,		ACT_HL2MP_IDLE_SMG1,		false },
			( ... )
			{ ACT_RANGE_ATTACK1,		ACT_RANGE_ATTACK_SMG1,		false },
			//HL2MP ANIMATIONS LIST END

			//HL2SP ANIMATIONS LIST START
			{ ACT_RANGE_ATTACK1,		ACT_RANGE_ATTACK_SMG1,		true },
			{ ACT_RELOAD,			ACT_RELOAD_SMG1,		true },
			{ ACT_IDLE,			ACT_IDLE_SMG1,			true },
			(...)
			{ ACT_GESTURE_RELOAD,		ACT_GESTURE_RELOAD_SMG1,	true },
			//HL2SP ANIMATIONS LIST END

		}

Other Weapons Modifications

Now you have to edit each weapon code by adding a few lines of code in their class definition. In each weapon class, add those declarations ( server side only ):

#ifndef CLIENT_DLL
	//ALLOW NPCS TO USE THE WEAPON TO SHOOT THEIR ENNEMIES
	int CapabilitiesGet( void ) { return bits_CAP_WEAPON_RANGE_ATTACK1; }
	//HANDLES AI'S ACTIVITIES
	void Operator_HandleAnimEvent( animevent_t *pEvent, CBaseCombatCharacter *pOperator );
#endif

NOTICE: You will find the Operator_HandleAnimEvent() function body in the SP-code of the weapon. Thus, do not forget to copy/paste it to avoid compiling errors!

Garry Newman's suggestion

Garry Newman suggested on forums to modify the SetActivity() function code. Thus, in the basecombatweapon_shared.cpp file, find the SetActivity() function, and then, after Adrian's comment:

//Adrian: Oh man...

replace

#if !defined( CLIENT_DLL ) && defined( HL2MP )
	SetModel( GetWorldModel() );
#endif

to

	if ( GetOwner()->IsPlayer() )
		SetModel( GetWorldModel() );

Proceed similarily after the other comment, so you replace:

	//Adrian: Oh man again...
#if !defined( CLIENT_DLL ) && defined( HL2MP )
	SetModel( GetViewModel() );
#endif

to

	//Adrian: Oh man again...
	if ( GetOwner()->IsPlayer() )
		SetModel( GetViewModel() );

Well, I don't now if that code fixes anything, I have not tried yet. I hope you will give me feedback about that piece of code.

Ammotypes

Well, if the NPCS kill you instantly - it happened to me - here's the tip to fix it. In the hl2mp_gamerules.cpp file, replace the whole CAmmoDef *GetAmmoDef() function to this:

CAmmoDef *GetAmmoDef()
	{
		static CAmmoDef def;
		static bool bInitted = false;
	
		if ( !bInitted )
		{
			bInitted = true;

			//THOMAS: HL2SP DEFINITIONS
			def.AddAmmoType("AR2",				DMG_BULLET,					TRACER_LINE_AND_WHIZ,		"sk_plr_dmg_ar2",		"sk_npc_dmg_ar2",			"sk_max_ar2",			BULLET_IMPULSE(200, 1225), 0 );
			def.AddAmmoType("AlyxGun",			DMG_BULLET,					TRACER_LINE,			"sk_plr_dmg_alyxgun",		"sk_npc_dmg_alyxgun",		"sk_max_alyxgun",			BULLET_IMPULSE(200, 1225), 0 );
			def.AddAmmoType("Pistol",			DMG_BULLET,					TRACER_LINE_AND_WHIZ,		"sk_plr_dmg_pistol",		"sk_npc_dmg_pistol",		"sk_max_pistol",			BULLET_IMPULSE(200, 1225), 0 );
			def.AddAmmoType("SMG1",				DMG_BULLET,					TRACER_LINE_AND_WHIZ,		"sk_plr_dmg_smg1",		"sk_npc_dmg_smg1",			"sk_max_smg1",			BULLET_IMPULSE(200, 1225), 0 );
			def.AddAmmoType("357",				DMG_BULLET,					TRACER_LINE_AND_WHIZ,	"	sk_plr_dmg_357",		"sk_npc_dmg_357",			"sk_max_357",			BULLET_IMPULSE(800, 5000), 0 );
			def.AddAmmoType("XBowBolt",			DMG_BULLET,					TRACER_LINE,			"sk_plr_dmg_crossbow",		"sk_npc_dmg_crossbow",		"sk_max_crossbow",			BULLET_IMPULSE(800, 8000), 0 );

			def.AddAmmoType("Buckshot",			DMG_BULLET | DMG_BUCKSHOT,			TRACER_LINE,			"sk_plr_dmg_buckshot",		"sk_npc_dmg_buckshot",		"sk_max_buckshot",			BULLET_IMPULSE(400, 1200), 0 );
			def.AddAmmoType("RPG_Round",			DMG_BURN,					TRACER_NONE,			"sk_plr_dmg_rpg_round",		"sk_npc_dmg_rpg_round",		"sk_max_rpg_round",		0, 0 );
			def.AddAmmoType("SMG1_Grenade",			DMG_BURN,					TRACER_NONE,			"sk_plr_dmg_smg1_grenade",	"sk_npc_dmg_smg1_grenade",	"sk_max_smg1_grenade",	0, 0 );
			def.AddAmmoType("Grenade",			DMG_BURN,					TRACER_NONE,			"sk_plr_dmg_grenade",		"sk_npc_dmg_grenade",		"sk_max_grenade",		0, 0);
			def.AddAmmoType("Thumper",			DMG_SONIC,					TRACER_NONE,			10, 10, 2, 0, 0 );
			def.AddAmmoType("Gravity",			DMG_CLUB,					TRACER_NONE,			0,	0, 8, 0, 0 );
			def.AddAmmoType("Battery",			DMG_CLUB,					TRACER_NONE,			NULL, NULL, NULL, 0, 0 );
			def.AddAmmoType("GaussEnergy",			DMG_SHOCK,					TRACER_NONE,			"sk_jeep_gauss_damage",		"sk_jeep_gauss_damage", "sk_max_gauss_round", BULLET_IMPULSE(650, 8000), 0 ); // hit like a 10kg weight at 400 in/s
			def.AddAmmoType("CombineCannon",		DMG_BULLET,					TRACER_LINE,			"sk_npc_dmg_gunship_to_plr", 	"sk_npc_dmg_gunship", NULL, 1.5 * 750 * 12, 0 ); // hit like a 1.5kg weight at 750 ft/s
			def.AddAmmoType("AirboatGun",			DMG_AIRBOAT,					TRACER_LINE,			"sk_plr_dmg_airboat",		"sk_npc_dmg_airboat",		NULL,					BULLET_IMPULSE(10, 600), 0 );
			def.AddAmmoType("StriderMinigun",		DMG_BULLET,					TRACER_LINE,			5, 5, 15, 1.0 * 750 * 12, AMMO_FORCE_DROP_IF_CARRIED ); // hit like a 1.0kg weight at 750 ft/s
			def.AddAmmoType("HelicopterGun",		DMG_BULLET,					TRACER_LINE_AND_WHIZ,		"sk_npc_dmg_helicopter_to_plr", "sk_npc_dmg_helicopter",	"sk_max_smg1",	BULLET_IMPULSE(400, 1225), AMMO_FORCE_DROP_IF_CARRIED | AMMO_INTERPRET_PLRDAMAGE_AS_DAMAGE_TO_PLAYER );
			def.AddAmmoType("AR2AltFire",			DMG_DISSOLVE,					TRACER_NONE,			0, 0, "sk_max_ar2_altfire", 0, 0 );
			//***
		}

		return &def;
	}

Let's Finish

Import skills data

Few people noticed that NPCs were not causing any damage to the player and that they could die instantly. This issue is simply caused by the fact the file skill.cfg is missing from the "\cfg" directory in the mod-dir. To fix it, get the skill.cfg file located in the Half-Lfe 2 folder.

Models Animations

You have to replace the HL2DM NPCS animations by the HL2 ones. Indeed HL2DM overrides the NPCs animations - used for the player models - so it breaks the AI. Thus, you have to use other models files for the players. You can hexedit the HL2DM player models & animations to make it tight. You will also have to put the HL2 original models in your \models folder. Finally, do not forget to modify the code related to the player models list in the hl2mp_player.cpp file.

Well, I don't want you to waste time hex-editing the model files, so I borrowed Garry's models, you can downoad the whoe package here: aifix.rar

Hope it helps! Happy modding!