From bca8d01ab3e5a4a64bbfa24af9bfbfd4b169993d Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Tue, 29 Jun 2021 01:34:14 +0200
Subject: [PATCH] - MBF21: infighting groups.

---
 src/gamedata/d_dehacked.cpp           | 36 ++++++++++++++++++---------
 src/gamedata/info.h                   |  3 +++
 src/playsim/p_interaction.cpp         | 14 ++++++++---
 src/scripting/thingdef_properties.cpp | 13 ++++++++++
 wadsrc/static/zscript/actors/actor.zs |  5 ++++
 5 files changed, 55 insertions(+), 16 deletions(-)

diff --git a/src/gamedata/d_dehacked.cpp b/src/gamedata/d_dehacked.cpp
index f2d48939b..3e9011b2a 100644
--- a/src/gamedata/d_dehacked.cpp
+++ b/src/gamedata/d_dehacked.cpp
@@ -949,20 +949,32 @@ static int PatchThing (int thingy)
 				hadStyle = true;
 			}
 		}
+		else if (linelen == 12 && stricmp(Line1, "No Ice Death") == 0)
+		{
+			if (val)
+			{
+				info->flags4 |= MF4_NOICEDEATH;
+			}
+			else
+			{
+				info->flags4 &= ~MF4_NOICEDEATH;
+			}
+		}
+		else if (linelen == 16 && stricmp(Line1, "infighting group") == 0)
+		{
+			stripwhite(Line2);
+			int grp = atoi(Line2);
+			if (grp < 0)
+			{
+				Printf("Infighting groups must be >= 0 (check your dehacked)\n");
+				grp = 0;
+			}
+			type->ActorInfo()->infighting_group = grp;
+		}
+
 		else if (linelen > 6)
 		{
-			if (linelen == 12 && stricmp (Line1, "No Ice Death") == 0)
-			{
-				if (val)
-				{
-					info->flags4 |= MF4_NOICEDEATH;
-				}
-				else
-				{
-					info->flags4 &= ~MF4_NOICEDEATH;
-				}
-			}
-			else if (stricmp (Line1 + linelen - 6, " frame") == 0)
+			if (stricmp (Line1 + linelen - 6, " frame") == 0)
 			{
 				FState *state = FindState (val);
 
diff --git a/src/gamedata/info.h b/src/gamedata/info.h
index ba2bbb335..0d2eadac4 100644
--- a/src/gamedata/info.h
+++ b/src/gamedata/info.h
@@ -245,6 +245,9 @@ struct FActorInfo
 	uint16_t SpawnID = 0;
 	uint16_t ConversationID = 0;
 	int16_t DoomEdNum = -1;
+	int infighting_group = 0;
+	int projectile_group = 0;
+	int splash_group = 0;
 
 	FStateLabels *StateList = nullptr;
 	DmgFactors DamageFactors;
diff --git a/src/playsim/p_interaction.cpp b/src/playsim/p_interaction.cpp
index 0e1b87611..a054b763c 100644
--- a/src/playsim/p_interaction.cpp
+++ b/src/playsim/p_interaction.cpp
@@ -1600,13 +1600,13 @@ bool AActor::OkayToSwitchTarget(AActor *other)
 	if (!(other->flags & MF_SHOOTABLE))
 		return false;		// Don't attack things that can't be hurt
 
-	if ((flags4 & MF4_NOTARGETSWITCH) && target != NULL)
+	if ((flags4 & MF4_NOTARGETSWITCH) && target != nullptr)
 		return false;		// Don't switch target if not allowed
 
-	if ((master != NULL && other->IsA(master->GetClass())) ||		// don't attack your master (or others of its type)
-		(other->master != NULL && IsA(other->master->GetClass())))	// don't attack your minion (or those of others of your type)
+	if ((master != nullptr && other->IsA(master->GetClass())) ||		// don't attack your master (or others of its type)
+		(other->master != nullptr && IsA(other->master->GetClass())))	// don't attack your minion (or those of others of your type)
 	{
-		if (!IsHostile (other) &&								// allow target switch if other is considered hostile
+		if (!IsHostile(other) &&								// allow target switch if other is considered hostile
 			(other->tid != TIDtoHate || TIDtoHate == 0) &&		// or has the tid we hate
 			other->TIDtoHate == TIDtoHate)						// or has different hate information
 		{
@@ -1614,6 +1614,12 @@ bool AActor::OkayToSwitchTarget(AActor *other)
 		}
 	}
 
+	// MBF21 support.
+	auto mygroup = GetClass()->ActorInfo()->infighting_group;
+	auto othergroup = other->GetClass()->ActorInfo()->infighting_group;
+	if (mygroup != 0 && mygroup == othergroup)
+		return false;
+
 	if ((flags7 & MF7_NOINFIGHTSPECIES) && GetSpecies() == other->GetSpecies())
 		return false;		// Don't fight own species.
 
diff --git a/src/scripting/thingdef_properties.cpp b/src/scripting/thingdef_properties.cpp
index d92e0a734..2120ae97b 100644
--- a/src/scripting/thingdef_properties.cpp
+++ b/src/scripting/thingdef_properties.cpp
@@ -1025,6 +1025,19 @@ DEFINE_PROPERTY(designatedteam, I, Actor)
 	defaults->DesignatedTeam = val;
 }
 
+//==========================================================================
+// MBF21
+//==========================================================================
+DEFINE_PROPERTY(infightinggroup, I, Actor)
+{
+	PROP_INT_PARM(i, 0);
+	if (i < 0)
+	{
+		I_Error("Infighting groups must be >= 0.");
+	}
+	info->ActorInfo()->infighting_group = i;
+}
+
 //==========================================================================
 // [BB]
 //==========================================================================
diff --git a/wadsrc/static/zscript/actors/actor.zs b/wadsrc/static/zscript/actors/actor.zs
index 2af204a71..508a5b20a 100644
--- a/wadsrc/static/zscript/actors/actor.zs
+++ b/wadsrc/static/zscript/actors/actor.zs
@@ -266,6 +266,11 @@ class Actor : Thinker native
 	meta Name MissileName;
 	meta double FastSpeed;		// speed in fast mode
 
+	// todo: implement access to native meta properties.
+	// native meta int infighting_group;
+	// native meta int projectile_group;
+	// native meta int splash_group;
+
 	Property prefix: none;
 	Property Obituary: Obituary;
 	Property HitObituary: HitObituary;