- Added support for THRU flags on bullets and rails.

- ALLOWTHRUFLAGS must be used on the puffs, added for the sake of compatibility with older mods. This applies to the following:
-- Bullets: THRUACTORS, THRUSPECIES
-- Rails: Same as bullets, but includes THRUGHOST.

src/actor.h

@@ -380,6 +380,7 @@ enum ActorFlag7
 	MF7_FORCEDECAL		= 0x00080000,	// [ZK] Forces puff's decal to override the weapon's.
 	MF7_LAXTELEFRAGDMG	= 0x00100000,	// [MC] Telefrag damage can be reduced.
 	MF7_ICESHATTER		= 0x00200000,	// [MC] Shatters ice corpses regardless of damagetype.
+	MF7_ALLOWTHRUFLAGS	= 0x00400000,	// [MC] Allow THRUACTORS and the likes on puffs to prevent mod breakage.
 };
 
 // --- mobj.renderflags ---

src/p_map.cpp

@@ -4023,8 +4023,11 @@ DAngle P_AimLineAttack(AActor *t1, DAngle angle, double distance, FTranslatedLin
 struct Origin
 {
 	AActor *Caller;
+	FNameNoInit PuffSpecies;
 	bool hitGhosts;
-	bool hitSameSpecies;
+	bool MThruSpecies;
+	bool ThruSpecies;
+	bool ThruActors;
 };
 
 static ETraceStatus CheckForActor(FTraceResults &res, void *userdata)
@@ -4036,17 +4039,16 @@ static ETraceStatus CheckForActor(FTraceResults &res, void *userdata)
 
 	Origin *data = (Origin *)userdata;
 
-	// check for physical attacks on spectrals
-	if (res.Actor->flags4 & MF4_SPECTRAL)
-	{
-		return TRACE_Skip;
-	}
+	// Skip actors if the puff has:
+	// 1. THRUACTORS or SPECTRAL
+	// 2. MTHRUSPECIES on puff and the shooter has same species as the hit actor
+	// 3. THRUSPECIES on puff and the puff has same species as the hit actor
+	// 4. THRUGHOST on puff and the GHOST flag on the hit actor
 
-	if (data->hitSameSpecies && res.Actor->GetSpecies() == data->Caller->GetSpecies()) 
-	{
-		return TRACE_Skip;
-	}
-	if (data->hitGhosts && res.Actor->flags3 & MF3_GHOST)
+	if ((data->ThruActors) || (res.Actor->flags4 & MF4_SPECTRAL) ||
+		(data->MThruSpecies && res.Actor->GetSpecies() == data->Caller->GetSpecies()) ||
+		(data->ThruSpecies && res.Actor->GetSpecies() == data->PuffSpecies) ||
+		(data->hitGhosts && res.Actor->flags3 & MF3_GHOST))
 	{
 		return TRACE_Skip;
 	}
@@ -4108,14 +4110,41 @@ AActor *P_LineAttack(AActor *t1, DAngle angle, double distance,
 
 	// We need to check the defaults of the replacement here
 	AActor *puffDefaults = GetDefaultByType(pufftype->GetReplacement());
-
+	
 	TData.hitGhosts = (t1->player != NULL &&
 		t1->player->ReadyWeapon != NULL &&
 		(t1->player->ReadyWeapon->flags2 & MF2_THRUGHOST)) ||
 		(puffDefaults && (puffDefaults->flags2 & MF2_THRUGHOST));
 
-	TData.hitSameSpecies = (puffDefaults && (puffDefaults->flags6 & MF6_MTHRUSPECIES));
+	TData.MThruSpecies = (puffDefaults && (puffDefaults->flags6 & MF6_MTHRUSPECIES));
+	TData.PuffSpecies = NAME_None;
 
+	// [MC] To prevent possible mod breakage, this flag is pretty much necessary.
+	// Somewhere, someone is relying on these to spawn on actors and move through them.
+
+	if ((puffDefaults->flags7 & MF7_ALLOWTHRUFLAGS))
+	{
+		TData.ThruSpecies = (puffDefaults && (puffDefaults->flags6 & MF6_THRUSPECIES));
+		TData.ThruActors = (puffDefaults && (puffDefaults->flags2 & MF2_THRUACTORS));
+
+		// [MC] Because this is a one-hit trace event, we need to spawn the puff, get the species
+		// and destroy it. Assume there is no species unless tempuff isn't NULL. We cannot get
+		// a proper species the same way as puffDefaults flags it appears...
+
+		AActor *tempuff = NULL;
+		if (pufftype != NULL)
+			tempuff = Spawn(pufftype, t1->Pos(), ALLOW_REPLACE);
+		if (tempuff != NULL)
+		{
+			TData.PuffSpecies = tempuff->GetSpecies();
+			tempuff->Destroy();
+		}
+	}
+	else
+	{
+		TData.ThruSpecies = false;
+		TData.ThruActors = false;
+	}
 	// if the puff uses a non-standard damage type, this will override default, hitscan and melee damage type.
 	// All other explicitly passed damage types (currenty only MDK) will be preserved.
 	if ((damageType == NAME_None || damageType == NAME_Melee || damageType == NAME_Hitscan) &&
@@ -4543,9 +4572,13 @@ struct RailData
 	AActor *Caller;
 	TArray<SRailHit> RailHits;
 	TArray<SPortalHit> PortalHits;
+	FNameNoInit PuffSpecies;
 	bool StopAtOne;
 	bool StopAtInvul;
+	bool ThruGhosts;
 	bool ThruSpecies;
+	bool MThruSpecies;
+	bool ThruActors;
 };
 
 static ETraceStatus ProcessRailHit(FTraceResults &res, void *userdata)
@@ -4572,8 +4605,16 @@ static ETraceStatus ProcessRailHit(FTraceResults &res, void *userdata)
 		return TRACE_Stop;
 	}
 
-	// Skip actors with the same species if the puff has MTHRUSPECIES.
-	if (data->ThruSpecies && res.Actor->GetSpecies() == data->Caller->GetSpecies())
+	// Skip actors if the puff has:
+	// 1. THRUACTORS (This one did NOT include a check for spectral)
+	// 2. MTHRUSPECIES on puff and the shooter has same species as the hit actor
+	// 3. THRUSPECIES on puff and the puff has same species as the hit actor
+	// 4. THRUGHOST on puff and the GHOST flag on the hit actor
+
+	if ((data->ThruActors) ||
+		(data->MThruSpecies && res.Actor->GetSpecies() == data->Caller->GetSpecies()) ||
+		(data->ThruSpecies && res.Actor->GetSpecies() == data->PuffSpecies) ||
+		(data->ThruGhosts && res.Actor->flags3 & MF3_GHOST))
 	{
 		return TRACE_Skip;
 	}
@@ -4648,7 +4689,27 @@ void P_RailAttack(FRailParams *p)
 	// disabled because not complete yet.
 	flags = (puffDefaults->flags6 & MF6_NOTRIGGER) ? TRACE_ReportPortals : TRACE_PCross | TRACE_Impact | TRACE_ReportPortals;
 	rail_data.StopAtInvul = (puffDefaults->flags3 & MF3_FOILINVUL) ? false : true;
-	rail_data.ThruSpecies = (puffDefaults->flags6 & MF6_MTHRUSPECIES) ? true : false;
+	rail_data.MThruSpecies = ((puffDefaults->flags6 & MF6_MTHRUSPECIES)) ? true : false;
+	
+	// Prevent mod breakage as somewhere, someone is relying on these to spawn on an actor 
+	// and move through them...
+	if ((puffDefaults->flags7 & MF7_ALLOWTHRUFLAGS))
+	{
+		rail_data.ThruGhosts = !!(puffDefaults->flags2 & MF2_THRUGHOST);
+		rail_data.ThruSpecies = !!(puffDefaults->flags6 & MF6_THRUSPECIES);
+		rail_data.ThruActors = !!(puffDefaults->flags2 & MF2_THRUACTORS);
+	}
+	else
+	{
+		rail_data.ThruGhosts = false;
+		rail_data.MThruSpecies = false;
+		rail_data.ThruActors = false;
+	}
+	// used as damage inflictor
+	AActor *thepuff = NULL;
+	
+	if (puffclass != NULL) thepuff = Spawn(puffclass, source->Pos(), ALLOW_REPLACE);
+		rail_data.PuffSpecies = (thepuff != NULL) ? thepuff->GetSpecies() : NAME_None;
 
 	Trace(start, source->Sector, vec, p->distance, MF_SHOOTABLE, ML_BLOCKEVERYTHING, source, trace,	flags, ProcessRailHit, &rail_data);
 
@@ -4656,11 +4717,6 @@ void P_RailAttack(FRailParams *p)
 	unsigned int i;
 	FName damagetype = (puffDefaults == NULL || puffDefaults->DamageType == NAME_None) ? FName(NAME_Railgun) : puffDefaults->DamageType;
 
-	// used as damage inflictor
-	AActor *thepuff = NULL;
-
-	if (puffclass != NULL) thepuff = Spawn(puffclass, source->Pos(), ALLOW_REPLACE);
-
 	for (i = 0; i < rail_data.RailHits.Size(); i++)
 	{
 		bool spawnpuff;

src/thingdef/thingdef_data.cpp

@@ -256,6 +256,7 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG(MF7, FORCEDECAL, AActor, flags7),
 	DEFINE_FLAG(MF7, LAXTELEFRAGDMG, AActor, flags7),
 	DEFINE_FLAG(MF7, ICESHATTER, AActor, flags7),
+	DEFINE_FLAG(MF7, ALLOWTHRUFLAGS, AActor, flags7),
 
 	// Effect flags
 	DEFINE_FLAG(FX, VISIBILITYPULSE, AActor, effects),