- added HARMFRIENDS flag.

src/actor.h

@@ -341,6 +341,7 @@ enum
 	MF7_ALWAYSTELEFRAG	= 0x00000004,	// will unconditionally be telefragged when in the way. Overrides all other settings.
 	MF7_HANDLENODELAY	= 0x00000008,	// respect NoDelay state flag
 	MF7_WEAPONSPAWN		= 0x00000010,	// subject to DF_NO_COOP_WEAPON_SPAWN dmflag
+	MF7_HARMFRIENDS		= 0x00000020,	// is allowed to harm friendly monsters.
 
 // --- mobj.renderflags ---
 

src/p_map.cpp

@@ -1111,9 +1111,11 @@ bool PIT_CheckThing(AActor *thing, FCheckPosition &tm)
 					//     cases where they are clearly supposed to do that
 					if (thing->IsFriend(tm.thing->target))
 					{
-						// Friends never harm each other
+						// Friends never harm each other, unless the shooter has the HARMFRIENDS set.
-						return false;
+						if (!(thing->flags7 & MF7_HARMFRIENDS)) return false;
 					}
+					else
+					{
 						if (thing->TIDtoHate != 0 && thing->TIDtoHate == tm.thing->target->TIDtoHate)
 						{
 							// [RH] Don't hurt monsters that hate the same thing as you do
@@ -1133,6 +1135,7 @@ bool PIT_CheckThing(AActor *thing, FCheckPosition &tm)
 							}
 						}
 					}
+				}
 				// else if (infight==1) any shot hurts anything - no further tests
 			}
 		}

src/thingdef/thingdef_data.cpp

@@ -241,6 +241,7 @@ static FFlagDef ActorFlags[]=
 	DEFINE_FLAG(MF7, NOTELESTOMP, AActor, flags7),
 	DEFINE_FLAG(MF7, ALWAYSTELEFRAG, AActor, flags7),
 	DEFINE_FLAG(MF7, WEAPONSPAWN, AActor, flags7),
+	DEFINE_FLAG(MF7, HARMFRIENDS, AActor, flags7),
 
 	// Effect flags
 	DEFINE_FLAG(FX, VISIBILITYPULSE, AActor, effects),