- added MF7_NOINFIGHTSPECIES flag.

src/actor.h

@@ -388,6 +388,7 @@ enum ActorFlag7
 	MF7_SMASHABLE		= 0x04000000,	// dies if hitting the floor.
 	MF7_NOSHIELDREFLECT = 0x08000000,	// will not be reflected by shields.
 	MF7_FORCEZERORADIUSDMG = 0x10000000,	// passes zero radius damage on to P_DamageMobj, this is necessary in some cases where DoSpecialDamage gets overrideen.
+	MF7_NOINFIGHTSPECIES = 0x20000000,	// don't start infights with one's own species.
 };
 
 // --- mobj.renderflags ---

src/p_interaction.cpp

@@ -1714,6 +1714,9 @@ bool AActor::OkayToSwitchTarget (AActor *other)
 		}
 	}
 
+	if ((flags7 & MF7_NOINFIGHTSPECIES) && GetSpecies() == target->GetSpecies())
+		return false;		// Don't fight own species.
+
 	if ((other->flags3 & MF3_NOTARGET) &&
 		(other->tid != TIDtoHate || TIDtoHate == 0) &&
 		!IsHostile (other))

src/scripting/thingdef_data.cpp

@@ -317,6 +317,7 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG(MF7, SMASHABLE, AActor, flags7),
 	DEFINE_FLAG(MF7, NOSHIELDREFLECT, AActor, flags7),
 	DEFINE_FLAG(MF7, FORCEZERORADIUSDMG, AActor, flags7),
+	DEFINE_FLAG(MF7, NOINFIGHTSPECIES, AActor, flags7),
 
 	// Effect flags
 	DEFINE_FLAG(FX, VISIBILITYPULSE, AActor, effects),