diff --git a/CMakeLists.txt b/CMakeLists.txt
index 199a1fca86..ce6a81dcde 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -48,12 +48,14 @@ function( add_pk3 PK3_NAME PK3_DIR )
 			COMMAND zipdir -udf ${ZDOOM_OUTPUT_DIR}/${PK3_NAME} ${PK3_DIR}
 			DEPENDS zipdir )
 	endif()
-
-		# Touch the zipdir executable here so that the pk3s are forced to
-		# rebuild each time since their dependecy has "changed."
-		add_custom_target( ${PK3_TARGET} ALL
-			COMMAND ${CMAKE_COMMAND} -E touch $<TARGET_FILE:zipdir>
-			DEPENDS ${ZDOOM_OUTPUT_DIR}/${PK3_NAME} )
+	# Grab a list of top-level PK3 folder files, so we can conveniently see them in the IDE
+	file(GLOB PK3_SRCS ${PK3_DIR}/*)
+	# Touch the zipdir executable here so that the pk3s are forced to
+	# rebuild each time since their dependecy has "changed."
+	add_custom_target( ${PK3_TARGET} ALL
+		COMMAND ${CMAKE_COMMAND} -E touch $<TARGET_FILE:zipdir>
+		DEPENDS ${ZDOOM_OUTPUT_DIR}/${PK3_NAME}
+		SOURCES "${PK3_SRCS}")
 endfunction()
 
 # Macro for building libraries without debugging information
diff --git a/src/actor.h b/src/actor.h
index bf76cc15ea..2ae26e7efb 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -417,7 +417,10 @@ enum ActorRenderFlag
 	RF_INVISIBLE		= 0x8000,	// Don't bother drawing this actor
 	RF_ROLLSPRITE		= 0x40000,	//[marrub]roll the sprite billboard
 	RF_DONTFLIP			= 0x80000,	// Don't flip it when viewed from behind.
-	RF_ROLLCENTER		= 0x100000, // Rotate from the center of sprite instead of offsets
+	RF_ROLLCENTER		= 0x00100000, // Rotate from the center of sprite instead of offsets
+	RF_MASKROTATION		= 0x00200000, // [MC] Only draw the actor when viewed from a certain angle range.
+	RF_ABSMASKANGLE		= 0x00400000, // [MC] The mask rotation does not offset by the actor's angle.
+	RF_ABSMASKPITCH		= 0x00800000, // [MC] The mask rotation does not offset by the actor's pitch.
 
 	RF_FORCEYBILLBOARD		= 0x10000,	// [BB] OpenGL only: draw with y axis billboard, i.e. anchored to the floor (overrides gl_billboard_mode setting)
 	RF_FORCEXYBILLBOARD		= 0x20000,	// [BB] OpenGL only: draw with xy axis billboard, i.e. unanchored (overrides gl_billboard_mode setting)
@@ -959,6 +962,7 @@ public:
 	inline void SetFriendPlayer(player_t *player);
 
 	bool IsVisibleToPlayer() const;
+	bool IsInsideVisibleAngles() const;
 
 	// Calculate amount of missile damage
 	virtual int GetMissileDamage(int mask, int add);
@@ -984,6 +988,10 @@ public:
 
 	DAngle			SpriteAngle;
 	DAngle			SpriteRotation;
+	DAngle			VisibleStartAngle;
+	DAngle			VisibleStartPitch;
+	DAngle			VisibleEndAngle;
+	DAngle			VisibleEndPitch;
 	DRotator		Angles;
 	DVector3		Vel;
 	double			Speed;
diff --git a/src/g_game.cpp b/src/g_game.cpp
index 5d1f83b828..629202ea5b 100644
--- a/src/g_game.cpp
+++ b/src/g_game.cpp
@@ -1884,7 +1884,7 @@ void G_DoLoadGame ()
 			}
 			else
 			{
-				Printf("Savegame is from another ZDoom-based engine: %s\n", engine);
+				Printf("Savegame is from another ZDoom-based engine: %s\n", engine.GetChars());
 			}
 			delete resfile;
 			return;
@@ -2261,7 +2261,7 @@ void G_DoSaveGame (bool okForQuicksave, FString filename, const char *descriptio
 	}
 
 	auto picdata = savepic.GetBuffer();
-	FCompressedBuffer bufpng = { picdata->Size(), picdata->Size(), METHOD_STORED, 0, crc32(0, &(*picdata)[0], picdata->Size()), (char*)&(*picdata)[0] };
+	FCompressedBuffer bufpng = { picdata->Size(), picdata->Size(), METHOD_STORED, 0, static_cast<unsigned int>(crc32(0, &(*picdata)[0], picdata->Size())), (char*)&(*picdata)[0] };
 
 	savegame_content.Push(bufpng);
 	savegame_filenames.Push("savepic.png");
diff --git a/src/gl/dynlights/a_dynlight.cpp b/src/gl/dynlights/a_dynlight.cpp
index 36ef1b9483..20d0d60782 100644
--- a/src/gl/dynlights/a_dynlight.cpp
+++ b/src/gl/dynlights/a_dynlight.cpp
@@ -163,7 +163,7 @@ void ADynamicLight::Serialize(FSerializer &arc)
 		("lighttype", lighttype, def->lighttype)
 		("tickcount", m_tickCount, def->m_tickCount)
 		("currentradius", m_currentRadius, def->m_currentRadius)
-		.Array("radius", m_Radius, def->m_Radius, 2);
+		.Array("lightradius", m_Radius, def->m_Radius, 2);
 
 	if (lighttype == PulseLight)
 		arc("lastupdate", m_lastUpdate, def->m_lastUpdate)
diff --git a/src/gl/scene/gl_sprite.cpp b/src/gl/scene/gl_sprite.cpp
index 123bf258cb..19753f742e 100644
--- a/src/gl/scene/gl_sprite.cpp
+++ b/src/gl/scene/gl_sprite.cpp
@@ -636,7 +636,7 @@ void GLSprite::Process(AActor* thing, sector_t * sector, int thruportal)
 	sector_t * rendersector;
 
 	// Don't waste time projecting sprites that are definitely not visible.
-	if (thing == nullptr || thing->sprite == 0 || !thing->IsVisibleToPlayer())
+	if (thing == nullptr || thing->sprite == 0 || !thing->IsVisibleToPlayer() || !thing->IsInsideVisibleAngles())
 	{
 		return;
 	}
diff --git a/src/namedef.h b/src/namedef.h
index f1279d27cc..c8b0d15246 100644
--- a/src/namedef.h
+++ b/src/namedef.h
@@ -336,6 +336,10 @@ xx(ReactionTime)
 xx(MeleeRange)
 xx(Speed)
 xx(Clamp)
+xx(VisibleStartAngle)
+xx(VisibleStartPitch)
+xx(VisibleEndAngle)
+xx(VisibleEndPitch)
 
 // Various actor names which are used internally
 xx(MapSpot)
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 657d5db49c..8d6d752379 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -306,7 +306,11 @@ void AActor::Serialize(FSerializer &arc)
 		A("spriteangle", SpriteAngle)
 		A("spriterotation", SpriteRotation)
 		("alternative", alternative)
-		A("tag", Tag);
+		A("tag", Tag)
+		A("visiblestartangle",VisibleStartAngle)
+		A("visibleendangle",VisibleEndAngle)
+		A("visiblestartpitch",VisibleStartPitch)
+		A("visibleendpitch",VisibleEndPitch);
 }
 
 #undef A
@@ -1019,6 +1023,69 @@ bool AActor::CheckLocalView (int playernum) const
 	return false;
 }
 
+//============================================================================
+//
+// AActor :: IsInsideVisibleAngles
+//
+// Returns true if this actor is within viewing angle/pitch visibility. 
+//
+//============================================================================
+
+bool AActor::IsInsideVisibleAngles() const
+{
+	// Don't bother masking if not wanted.
+	if (!(renderflags & RF_MASKROTATION))
+		return true;
+
+	if (players[consoleplayer].camera == nullptr)
+		return true;
+	
+	DAngle anglestart = VisibleStartAngle.Normalized180();
+	DAngle angleend = VisibleEndAngle.Normalized180();
+	DAngle pitchstart = VisibleStartPitch.Normalized180();
+	DAngle pitchend = VisibleEndPitch.Normalized180();
+
+	if (anglestart > angleend)
+	{
+		DAngle temp = anglestart;
+		anglestart = angleend;
+		angleend = temp;
+	}
+
+	if (pitchstart > angleend)
+	{
+		DAngle temp = pitchstart;
+		pitchstart = pitchend;
+		pitchend = temp;
+	}
+
+	player_t* pPlayer = players[consoleplayer].camera->player;
+
+	if (pPlayer && pPlayer->mo)
+	{
+		AActor *mo = pPlayer->mo;
+		DVector3 diffang = Vec3To(mo);
+		DAngle to = diffang.Angle();
+
+		if (!(renderflags & RF_ABSMASKANGLE)) 
+			to = deltaangle(Angles.Yaw, to);
+
+		// Note that this check is inversed due to only being able to vectorize
+		// from one way (this actor to the player). It still means to pass
+		// if the player is within the visible angles.
+		if ((to <= anglestart || to >= angleend))
+		{
+			to = diffang.Pitch();
+			if (!(renderflags & RF_ABSMASKPITCH))
+				to = deltaangle(Angles.Pitch, to);
+
+			return !!(to >= pitchstart && to <= pitchend);
+		}
+		else return false;
+	}
+	return true;
+}
+
 //============================================================================
 //
 // AActor :: IsVisibleToPlayer
diff --git a/src/r_things.cpp b/src/r_things.cpp
index 6f1fb2700c..49d7333faa 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -761,7 +761,8 @@ void R_ProjectSprite (AActor *thing, int fakeside, F3DFloor *fakefloor, F3DFloor
 	if (thing == NULL ||
 		(thing->renderflags & RF_INVISIBLE) ||
 		!thing->RenderStyle.IsVisible(thing->Alpha) ||
-		!thing->IsVisibleToPlayer())
+		!thing->IsVisibleToPlayer() ||
+		!thing->IsInsideVisibleAngles())
 	{
 		return;
 	}
diff --git a/src/serializer.cpp b/src/serializer.cpp
index ae1c55a7a7..a23459ced0 100644
--- a/src/serializer.cpp
+++ b/src/serializer.cpp
@@ -859,7 +859,7 @@ void FSerializer::ReadObjects(bool hubtravel)
 					PClass *cls = PClass::FindClass(clsname);
 					if (cls == nullptr)
 					{
-						Printf("Unknown object class '%d' in savegame", clsname.GetChars());
+						Printf("Unknown object class '%s' in savegame", clsname.GetChars());
 						founderrors = true;
 						r->mDObjects[i] = RUNTIME_CLASS(AActor)->CreateNew();	// make sure we got at least a valid pointer for the duration of the loading process.
 						r->mDObjects[i]->Destroy();								// but we do not want to keep this around, so destroy it right away.
diff --git a/src/serializer.h b/src/serializer.h
index f1d35e1f88..a3e1f531ea 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -163,7 +163,7 @@ public:
 	template<class T>
 	FSerializer &Enum(const char *key, T &obj)
 	{
-		auto val = (std::underlying_type<T>::type)obj;
+		auto val = (typename std::underlying_type<T>::type)obj;
 		Serialize(*this, key, val, nullptr);
 		obj = (T)val;
 		return *this;
@@ -299,4 +299,4 @@ FSerializer &Serialize(FSerializer &arc, const char *key, TFlags<T, TT> &flags,
 }
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 21551364bc..153c3b5970 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -7344,3 +7344,55 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetSpriteRotation)
 	mobj->SpriteRotation = angle;
 	ACTION_RETURN_BOOL(true);
 }
+
+//==========================================================================
+//
+// A_SetMaskRotation(anglestart, angleend, pitchstart, pitchend, flags, ptr)
+//
+// Specifies how much to fake a sprite rotation.
+//==========================================================================
+
+enum VRFFlags
+{
+	VRF_NOANGLESTART =		1,
+	VRF_NOANGLEEND =		1 << 1,
+	VRF_NOPITCHSTART =		1 << 2,
+	VRF_NOPITCHEND =		1 << 3,
+};
+
+DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetVisibleRotation)
+{
+	PARAM_ACTION_PROLOGUE;
+	PARAM_ANGLE_OPT(anglestart) { anglestart = 0.;	}
+	PARAM_ANGLE_OPT(angleend)	{ angleend = 0.;	}
+	PARAM_ANGLE_OPT(pitchstart) { pitchstart = 0.;	}
+	PARAM_ANGLE_OPT(pitchend)	{ pitchend = 0.;	}
+	PARAM_INT_OPT(flags)		{ flags = 0; }
+	PARAM_INT_OPT(ptr)			{ ptr = AAPTR_DEFAULT; }
+
+	AActor *mobj = COPY_AAPTR(self, ptr);
+
+	if (mobj == nullptr)
+	{
+		ACTION_RETURN_BOOL(false);
+	}
+		
+	if (!(flags & VRF_NOANGLESTART))
+	{
+		mobj->VisibleStartAngle = anglestart;
+	}
+	if (!(flags & VRF_NOANGLEEND))
+	{
+		mobj->VisibleEndAngle = angleend;
+	}
+	if (!(flags & VRF_NOPITCHSTART))
+	{
+		mobj->VisibleStartPitch = pitchstart;
+	}
+	if (!(flags & VRF_NOPITCHEND))
+	{
+		mobj->VisibleEndPitch = pitchend;
+	}
+
+	ACTION_RETURN_BOOL(true);
+}
diff --git a/src/thingdef/thingdef_data.cpp b/src/thingdef/thingdef_data.cpp
index 8248634a38..efdd649216 100644
--- a/src/thingdef/thingdef_data.cpp
+++ b/src/thingdef/thingdef_data.cpp
@@ -275,6 +275,9 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG(RF, WALLSPRITE, AActor, renderflags),
 	DEFINE_FLAG(RF, DONTFLIP, AActor, renderflags),
 	DEFINE_FLAG(RF, ROLLCENTER, AActor, renderflags),
+	DEFINE_FLAG(RF, MASKROTATION, AActor, renderflags),
+	DEFINE_FLAG(RF, ABSMASKANGLE, AActor, renderflags),
+	DEFINE_FLAG(RF, ABSMASKPITCH, AActor, renderflags),
 
 	// Bounce flags
 	DEFINE_FLAG2(BOUNCE_Walls, BOUNCEONWALLS, AActor, BounceFlags),
@@ -667,4 +670,8 @@ void InitThingdef()
 	symt.AddSymbol(new PField(NAME_Threshold,		TypeSInt32,		VARF_Native|VARF_ReadOnly,	myoffsetof(AActor, threshold)));
 	symt.AddSymbol(new PField(NAME_DefThreshold,	TypeSInt32,		VARF_Native|VARF_ReadOnly,	myoffsetof(AActor, DefThreshold)));
 	symt.AddSymbol(new PField(NAME_Damage,			TypeSInt32,		VARF_Native|VARF_ReadOnly,  myoffsetof(AActor, DamageVal)));
+	symt.AddSymbol(new PField(NAME_VisibleStartAngle, TypeFloat64,	VARF_Native,				myoffsetof(AActor, VisibleStartAngle)));
+	symt.AddSymbol(new PField(NAME_VisibleStartPitch, TypeFloat64,	VARF_Native,				myoffsetof(AActor, VisibleStartPitch)));
+	symt.AddSymbol(new PField(NAME_VisibleEndAngle,	TypeFloat64,	VARF_Native,				myoffsetof(AActor, VisibleEndAngle)));
+	symt.AddSymbol(new PField(NAME_VisibleEndPitch, TypeFloat64,	VARF_Native,				myoffsetof(AActor, VisibleEndPitch)));
 }
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index 3cb424ea32..8ada05aa67 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -1431,6 +1431,28 @@ DEFINE_PROPERTY(spriterotation, F, Actor)
 	defaults->SpriteRotation = i;
 }
 
+//==========================================================================
+//
+//==========================================================================
+DEFINE_PROPERTY(visibleangles, Ff, Actor)
+{
+	PROP_DOUBLE_PARM(visstart, 0);
+	PROP_DOUBLE_PARM(visend, 0);
+	defaults->VisibleStartAngle = visstart;
+	defaults->VisibleEndAngle = visend;
+}
+
+//==========================================================================
+//
+//==========================================================================
+DEFINE_PROPERTY(visiblepitch, Ff, Actor)
+{
+	PROP_DOUBLE_PARM(visstart, 0);
+	PROP_DOUBLE_PARM(visend, 0);
+	defaults->VisibleStartPitch = visstart;
+	defaults->VisibleEndPitch = visend;
+}
+
 //==========================================================================
 //
 //==========================================================================
diff --git a/src/version.h b/src/version.h
index a88d3e20b3..0c9b851206 100644
--- a/src/version.h
+++ b/src/version.h
@@ -75,7 +75,7 @@ const char *GetVersionString();
 #define SAVEGAME_EXT "zds"
 
 // MINSAVEVER is the minimum level snapshot version that can be loaded.
-#define MINSAVEVER	4545
+#define MINSAVEVER	4550
 
 // Use 4500 as the base git save version, since it's higher than the
 // SVN revision ever got.
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index 374e2472d1..3354b91d63 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -38,6 +38,8 @@ ACTOR Actor native //: Thinker
 	SpriteAngle 0
 	SpriteRotation 0
 	StencilColor "00 00 00"
+	VisibleAngles 0, 0
+	VisiblePitch 0, 0
 
 	// Functions
 	native bool CheckClass(class<Actor> checkclass, int ptr_select = AAPTR_DEFAULT, bool match_superclass = false);
@@ -340,6 +342,7 @@ ACTOR Actor native //: Thinker
 	action native bool A_CopySpriteFrame(int from, int to, int flags = 0);
 	action native bool A_SetSpriteAngle(float angle = 0, int ptr = AAPTR_DEFAULT);
 	action native bool A_SetSpriteRotation(float angle = 0, int ptr = AAPTR_DEFAULT);
+	action native bool A_SetVisibleRotation(float anglestart = 0, float angleend = 0, float pitchstart = 0, float pitchend = 0, int flags = 0, int ptr = AAPTR_DEFAULT);
 
 	native void A_RearrangePointers(int newtarget, int newmaster = AAPTR_DEFAULT, int newtracer = AAPTR_DEFAULT, int flags=0);
 	native void A_TransferPointer(int ptr_source, int ptr_recepient, int sourcefield, int recepientfield=AAPTR_DEFAULT, int flags=0);
diff --git a/wadsrc/static/actors/constants.txt b/wadsrc/static/actors/constants.txt
index 2a6f1c4836..bd6d656434 100644
--- a/wadsrc/static/actors/constants.txt
+++ b/wadsrc/static/actors/constants.txt
@@ -677,4 +677,16 @@ enum
 {
 	CPSF_NOSPRITE =			1,
 	CPSF_NOFRAME =			1 << 1,
+};
+
+//Flags for A_SetMaskRotation
+enum
+{
+	VRF_NOANGLESTART =		1,
+	VRF_NOANGLEEND =		1 << 1,
+	VRF_NOPITCHSTART =		1 << 2,
+	VRF_NOPITCHEND =		1 << 3,
+
+	VRF_NOANGLE = VRF_NOANGLESTART|VRF_NOANGLEEND,
+	VRF_NOPITCH = VRF_NOPITCHSTART|VRF_NOPITCHEND,
 };
\ No newline at end of file