Fixes and hacks for HL2 NPCs performing dynamic interactions

sp/src/game/server/ai_basenpc.cpp

@@ -13515,6 +13515,10 @@ bool CAI_BaseNPC::CineCleanup()
 		}
 
 		// Clear interaction partner, because we're not running a scripted sequence anymore
+#ifdef MAPBASE
+		// We need the interaction partner for server ragdoll death cleanup, so don't clear if we're not alive
+		if (IsAlive())
+#endif
 		m_hInteractionPartner = NULL;
 		CleanupForcedInteraction();
 	}

sp/src/game/server/hl2/npc_BaseZombie.cpp

@@ -2435,6 +2435,20 @@ void CNPC_BaseZombie::RemoveHead( void )
 }
 
 
+//---------------------------------------------------------
+//---------------------------------------------------------
+void CNPC_BaseZombie::SetModel( const char *szModelName )
+{
+#ifdef MAPBASE
+	// Zombies setting the same model again is a problem when they should maintain their current sequence (e.g. during dynamic interactions)
+	if ( IsRunningDynamicInteraction() && GetModelIndex() != 0 && FStrEq( szModelName, STRING(GetModelName()) ) )
+		return;
+#endif
+
+	BaseClass::SetModel( szModelName );
+}
+
+
 bool CNPC_BaseZombie::ShouldPlayFootstepMoan( void )
 {
 	if( random->RandomInt( 1, zombie_stepfreq.GetInt() * s_iAngryZombies ) == 1 )

sp/src/game/server/hl2/npc_BaseZombie.h

@@ -186,6 +186,7 @@ public:
 	// Headcrab releasing/breaking apart
 	void RemoveHead( void );
 	virtual void SetZombieModel( void ) { };
+	virtual void SetModel( const char *szModelName );
 	virtual void BecomeTorso( const Vector &vecTorsoForce, const Vector &vecLegsForce );
 	virtual bool CanBecomeLiveTorso() { return false; }
 	virtual bool HeadcrabFits( CBaseAnimating *pCrab );

sp/src/game/server/hl2/npc_combine.cpp

@@ -47,6 +47,8 @@ ConVar npc_combine_protected_run( "npc_combine_protected_run", "0", FCVAR_NONE,
 ConVar npc_combine_altfire_not_allies_only( "npc_combine_altfire_not_allies_only", "1", FCVAR_NONE, "Mapbase: Elites are normally only allowed to fire their alt-fire attack at the player and the player's allies; This allows elites to alt-fire at other enemies too." );
 
 ConVar npc_combine_new_cover_behavior( "npc_combine_new_cover_behavior", "1", FCVAR_NONE, "Mapbase: Toggles small patches for parts of npc_combine AI related to soldiers failing to take cover. These patches are minimal and only change cases where npc_combine would otherwise look at an enemy without shooting or run up to the player to melee attack when they don't have to. Consult the Mapbase wiki for more information." );
+
+ConVar npc_combine_fixed_shootpos( "npc_combine_fixed_shootpos", "0", FCVAR_NONE, "Mapbase: Toggles fixed Combine soldier shoot position." )
 #endif
 
 #define COMBINE_SKIN_DEFAULT		0
@@ -2959,6 +2961,28 @@ Vector CNPC_Combine::Weapon_ShootPosition( )
 	// FIXME: rename this "estimated" since it's not based on animation
 	// FIXME: the orientation won't be correct when testing from arbitary positions for arbitary angles
 
+#ifdef MAPBASE
+	// HACKHACK: This weapon shoot position code does not work properly when in close range, causing the aim
+	// to drift to the left as the enemy gets closer to it.
+	// This problem is usually bearable for regular combat, but it causes dynamic interaction yaw to be offset
+	// as well, preventing most from ever being triggered.
+	// Ideally, this should be fixed from the root cause, but due to the sensitivity of such a change, this is
+	// currently being tied to a cvar which is off by default.
+	// 
+	// If the cvar is disabled but the soldier has valid interactions on its current enemy, then a separate hack
+	// will still attempt to correct the drift as the enemy gets closer.
+	if ( npc_combine_fixed_shootpos.GetBool() )
+	{
+		right *= 0.0f;
+	}
+	else if ( HasValidInteractionsOnCurrentEnemy() )
+	{
+		float flDistSqr = GetEnemy()->WorldSpaceCenter().DistToSqr( WorldSpaceCenter() );
+		if (flDistSqr < Square( 128.0f ))
+			right *= (flDistSqr / Square( 128.0f ));
+	}
+#endif
+
 	if  ( bStanding )
 	{
 		if( HasShotgun() )

sp/src/game/server/physics_prop_ragdoll.cpp

@@ -1557,6 +1557,16 @@ CBaseEntity *CreateServerRagdoll( CBaseAnimating *pAnimating, int forceBone, con
 	pRagdoll->CollisionProp()->SetCollisionBounds( mins, maxs );
 
 #ifdef MAPBASE
+	// If this was a NPC running a dynamic interaction, disable collisions with the interaction partner
+	if (pAnimating->IsNPC() /*&& pAnimating->MyNPCPointer()->IsRunningDynamicInteraction()*/)
+	{
+		CAI_BaseNPC *pNPC = pAnimating->MyNPCPointer();
+		if (pNPC->GetInteractionPartner() && pNPC->GetInteractionPartner()->VPhysicsGetObject())
+		{
+			PhysDisableEntityCollisions( pRagdoll, pNPC->GetInteractionPartner() );
+		}
+	}
+
 	variant_t variant;
 	variant.SetEntity(pRagdoll);
 	pAnimating->FireNamedOutput("OnServerRagdoll", variant, pRagdoll, pAnimating);