diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 86adf047a..66eb3fa4e 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -480,7 +480,7 @@ if( ZD_CMAKE_COMPILER_IS_GNUCXX_COMPATIBLE )
 		set( CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -pg" )
 		set( CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -pg" )
 	endif()
-	
+
 	set( REL_CXX_FLAGS "-fno-rtti" )
 	if( NOT PROFILE AND NOT APPLE )
 		# On OS X frame pointers are required for exception handling, at least with Clang
@@ -497,6 +497,30 @@ if( ZD_CMAKE_COMPILER_IS_GNUCXX_COMPATIBLE )
 	set( CMAKE_C_FLAGS "-Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-missing-field-initializers ${CMAKE_C_FLAGS}" )
 	set( CMAKE_CXX_FLAGS "-Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-missing-field-initializers ${CMAKE_CXX_FLAGS}" )
 
+	# Use the highest C++ standard available since VS2015 compiles with C++14
+	# but we only require C++11.  The recommended way to do this in CMake is to
+	# probably to use target_compile_features, but I don't feel like maintaining
+	# a list of features we use.
+	CHECK_CXX_COMPILER_FLAG( "-std=c++14" CAN_DO_CPP14 )
+	if ( CAN_DO_CPP14 )
+		set ( CMAKE_CXX_FLAGS "-std=c++14 ${CMAKE_CXX_FLAGS}" )
+	else ()
+		CHECK_CXX_COMPILER_FLAG( "-std=c++1y" CAN_DO_CPP1Y )
+		if ( CAN_DO_CPP1Y )
+			set ( CMAKE_CXX_FLAGS "-std=c++1y ${CMAKE_CXX_FLAGS}" )
+		else ()
+			CHECK_CXX_COMPILER_FLAG( "-std=c++11" CAN_DO_CPP11 )
+			if ( CAN_DO_CPP11 )
+				set ( CMAKE_CXX_FLAGS "-std=c++11 ${CMAKE_CXX_FLAGS}" )
+			else ()
+				CHECK_CXX_COMPILER_FLAG( "-std=c++0x" CAN_DO_CPP0X )
+				if ( CAN_DO_CPP0X )
+					set ( CMAKE_CXX_FLAGS "-std=c++0x ${CMAKE_CXX_FLAGS}" )
+				endif ()
+			endif ()
+		endif ()
+	endif ()
+
 	# Remove extra warnings when using the official DirectX headers.
 	# Also, TDM-GCC 4.4.0 no longer accepts glibc-style printf formats as valid,
 	# which is a royal pain. The previous version I had been using was fine with them.
diff --git a/src/am_map.cpp b/src/am_map.cpp
index 28bd27aff..aac56f1c2 100644
--- a/src/am_map.cpp
+++ b/src/am_map.cpp
@@ -1695,9 +1695,9 @@ bool AM_clipMline (mline_t *ml, fline_t *fl)
 		TOP		=8
 	};
 
-	register int outcode1 = 0;
-	register int outcode2 = 0;
-	register int outside;
+	int outcode1 = 0;
+	int outcode2 = 0;
+	int outside;
 
 	fpoint_t tmp = { 0, 0 };
 	int dx;
diff --git a/src/doomdef.h b/src/doomdef.h
index 3b066f8d8..12a9dbfe9 100644
--- a/src/doomdef.h
+++ b/src/doomdef.h
@@ -302,7 +302,7 @@ enum
 };
 
 // [RH] Compatibility flags.
-enum
+enum : unsigned int
 {
 	COMPATF_SHORTTEX		= 1 << 0,	// Use Doom's shortest texture around behavior?
 	COMPATF_STAIRINDEX		= 1 << 1,	// Don't fix loop index for stair building?
diff --git a/src/g_level.h b/src/g_level.h
index 6e1768c3a..b6b848674 100644
--- a/src/g_level.h
+++ b/src/g_level.h
@@ -125,7 +125,7 @@ struct FMapOptInfo
 	bool old;
 };
 
-enum ELevelFlags
+enum ELevelFlags : unsigned int
 {
 	LEVEL_NOINTERMISSION		= 0x00000001,
 	LEVEL_NOINVENTORYBAR		= 0x00000002,	// This effects Doom only, since it's the only one without a standard inventory bar.
diff --git a/src/md5.cpp b/src/md5.cpp
index 481774c7a..b81209546 100644
--- a/src/md5.cpp
+++ b/src/md5.cpp
@@ -166,7 +166,7 @@ void MD5Context::Final(BYTE digest[16])
 void
 MD5Transform(DWORD buf[4], const DWORD in[16])
 {
-	register DWORD a, b, c, d;
+	DWORD a, b, c, d;
 
 	a = buf[0];
 	b = buf[1];
diff --git a/src/p_local.h b/src/p_local.h
index 35dbb8b22..7e11010c5 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -243,6 +243,7 @@ extern msecnode_t		*sector_list;		// phares 3/16/98
 struct spechit_t
 {
 	line_t *line;
+	fixedvec2 oldrefpos;
 	fixedvec2 refpos;
 };
 
diff --git a/src/p_map.cpp b/src/p_map.cpp
index 66b4d39e4..7908ce4a9 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -808,6 +808,18 @@ bool PIT_CheckLine(FMultiBlockLinesIterator &mit, FMultiBlockLinesIterator::Chec
 
 	if (!ld->backsector)
 	{ // One sided line
+
+		// Needed for polyobject portals. Having two-sided lines just for portals on otherwise solid polyobjects is a messy subject.
+		if ((cres.line->sidedef[0]->Flags & WALLF_POLYOBJ) && cres.line->isLinePortal())
+		{
+			spechit_t spec;
+			spec.line = ld;
+			spec.refpos = cres.position;
+			spec.oldrefpos = tm.thing->PosRelative(ld);
+			portalhit.Push(spec);
+			return true;
+		}
+
 		if (((cres.portalflags & FFCF_NOFLOOR) && LineIsAbove(cres.line, tm.thing) != 0) ||
 			((cres.portalflags & FFCF_NOCEILING) && LineIsBelow(cres.line, tm.thing) != 0))
 		{
@@ -969,18 +981,122 @@ bool PIT_CheckLine(FMultiBlockLinesIterator &mit, FMultiBlockLinesIterator::Chec
 	{
 		spec.line = ld;
 		spec.refpos = cres.position;
+		spec.oldrefpos = tm.thing->PosRelative(ld);
 		spechit.Push(spec);
 	}
-	if (ld->portalindex >= 0 && ld->portalindex != UINT_MAX)
+	if (ld->portalindex != UINT_MAX)
 	{
 		spec.line = ld;
 		spec.refpos = cres.position;
+		spec.oldrefpos = tm.thing->PosRelative(ld);
 		portalhit.Push(spec);
 	}
 
 	return true;
 }
 
+//==========================================================================
+//
+//
+// PIT_CheckPortal
+// This checks the destination side of a non-static line portal
+// We cannot run a full P_CheckPosition there because it'd set 
+// multiple fields to values that can cause problems in other
+// parts of the code
+// 
+// What this does is starting a separate BlockLinesIterator
+// and only taking the absolutely necessary information
+// (i.e. floor and ceiling height plus terrain)
+// 
+//
+//==========================================================================
+
+static bool PIT_CheckPortal(FMultiBlockLinesIterator &mit, FMultiBlockLinesIterator::CheckResult cres, const FBoundingBox &box, FCheckPosition &tm)
+{
+	// if in another vertical section let's just ignore it.
+	if (cres.portalflags & (FFCF_NOCEILING | FFCF_NOFLOOR)) return false;
+
+	if (box.Right() <= cres.line->bbox[BOXLEFT]
+		|| box.Left() >= cres.line->bbox[BOXRIGHT]
+		|| box.Top() <= cres.line->bbox[BOXBOTTOM]
+		|| box.Bottom() >= cres.line->bbox[BOXTOP])
+		return false;
+
+	if (box.BoxOnLineSide(cres.line) != -1)
+		return false;
+
+	line_t *lp = cres.line->getPortalDestination();
+	fixed_t zofs = 0;
+
+	P_TranslatePortalXY(cres.line, lp, cres.position.x, cres.position.y);
+	P_TranslatePortalZ(cres.line, lp, zofs);
+
+	// fudge a bit with the portal line so that this gets included in the checks that normally only get run on two-sided lines
+	sector_t *sec = lp->backsector;
+	if (lp->backsector == NULL) lp->backsector = lp->frontsector;
+	tm.thing->AddZ(zofs);
+
+	FBoundingBox pbox(cres.position.x, cres.position.y, tm.thing->radius);
+	FBlockLinesIterator it(pbox);
+	bool ret = false;
+	line_t *ld;
+
+	// Check all lines at the destination
+	while ((ld = it.Next()))
+	{
+		if (pbox.Right() <= ld->bbox[BOXLEFT]
+			|| pbox.Left() >= ld->bbox[BOXRIGHT]
+			|| pbox.Top() <= ld->bbox[BOXBOTTOM]
+			|| pbox.Bottom() >= ld->bbox[BOXTOP])
+			continue;
+
+		if (pbox.BoxOnLineSide(ld) != -1)
+			continue;
+
+		if (ld->backsector == NULL) 
+			continue;
+
+		fixedvec2 ref = FindRefPoint(ld, cres.position);
+		FLineOpening open;
+
+		P_LineOpening(open, tm.thing, ld, ref.x, ref.y, cres.position.x, cres.position.y, 0);
+
+		// adjust floor / ceiling heights
+		if (open.top - zofs < tm.ceilingz)
+		{
+			tm.ceilingz = open.top - zofs;
+			tm.ceilingpic = open.ceilingpic;
+			/*
+			tm.ceilingsector = open.topsec;
+			tm.ceilingline = ld;
+			tm.thing->BlockingLine = ld;
+			*/
+			ret = true;
+		}
+
+		if (open.bottom - zofs > tm.floorz)
+		{
+			tm.floorz = open.bottom - zofs;
+			tm.floorpic = open.floorpic;
+			tm.floorterrain = open.floorterrain;
+			/*
+			tm.floorsector = open.bottomsec;
+			tm.touchmidtex = open.touchmidtex;
+			tm.abovemidtex = open.abovemidtex;
+			tm.thing->BlockingLine = ld;
+			*/
+			ret = true;
+		}
+
+		if (open.lowfloor - zofs < tm.dropoffz)
+			tm.dropoffz = open.lowfloor - zofs;
+	}
+	tm.thing->AddZ(-zofs);
+	lp->backsector = sec;
+
+	return ret;
+}
+
 
 //==========================================================================
 //
@@ -1526,7 +1642,6 @@ bool P_CheckPosition(AActor *thing, fixed_t x, fixed_t y, FCheckPosition &tm, bo
 	tm.touchmidtex = false;
 	tm.abovemidtex = false;
 	validcount++;
-	spechit.Clear();
 
 	if ((thing->flags & MF_NOCLIP) && !(thing->flags & MF_SKULLFLY))
 		return true;
@@ -1610,6 +1725,9 @@ bool P_CheckPosition(AActor *thing, fixed_t x, fixed_t y, FCheckPosition &tm, bo
 	if (actorsonly || (thing->flags & MF_NOCLIP))
 		return (thing->BlockingMobj = thingblocker) == NULL;
 
+	spechit.Clear();
+	portalhit.Clear();
+
 	FMultiBlockLinesIterator it(pcheck, x, y, thing->Z(), thing->height, thing->radius);
 	FMultiBlockLinesIterator::CheckResult lcres;
 
@@ -1621,7 +1739,22 @@ bool P_CheckPosition(AActor *thing, fixed_t x, fixed_t y, FCheckPosition &tm, bo
 
 	while (it.Next(&lcres))
 	{
-		good &= PIT_CheckLine(it, lcres, it.Box(), tm);
+		bool thisresult = PIT_CheckLine(it, lcres, it.Box(), tm);
+		good &= thisresult;
+		if (thisresult)
+		{
+			FLinePortal *port = lcres.line->getPortal();
+			if (port != NULL && port->mFlags & PORTF_PASSABLE && port->mType != PORTT_LINKED)
+			{
+				// Checking the other side of the portal completely is too costly,
+				// but checking the portal's destination line is necessary to 
+				// retrieve the proper sector heights on the other side.
+				if (PIT_CheckPortal(it, lcres, it.Box(), tm))
+				{
+					tm.thing->BlockingLine = lcres.line;
+				}
+			}
+		}
 	}
 	if (!good)
 	{
@@ -2132,22 +2265,126 @@ bool P_TryMove(AActor *thing, fixed_t x, fixed_t y,
 		return false;
 	}
 
-	// the move is ok, so link the thing into its new position
-	thing->UnlinkFromWorld();
 
-	oldpos = thing->Pos();
-	oldsector = thing->Sector;
-	thing->floorz = tm.floorz;
-	thing->ceilingz = tm.ceilingz;
-	thing->dropoffz = tm.dropoffz;		// killough 11/98: keep track of dropoffs
-	thing->floorpic = tm.floorpic;
-	thing->floorterrain = tm.floorterrain;
-	thing->floorsector = tm.floorsector;
-	thing->ceilingpic = tm.ceilingpic;
-	thing->ceilingsector = tm.ceilingsector;
-	thing->SetXY(x, y);
+	// Check for crossed portals
+	bool portalcrossed;
+	portalcrossed = false;
 
-	thing->LinkToWorld();
+	while (true)
+	{
+		fixed_t bestfrac = FIXED_MAX;
+		spechit_t besthit;
+		// find the portal nearest to the crossing actor
+		for (auto &spec : portalhit)
+		{
+			line_t *ld = spec.line;
+			if (ld->frontsector->PortalGroup != thing->Sector->PortalGroup) continue;	// must be in the same group to be considered valid.
+
+			// see if the line was crossed
+			oldside = P_PointOnLineSide(spec.oldrefpos.x, spec.oldrefpos.y, ld);
+			side = P_PointOnLineSide(spec.refpos.x, spec.refpos.y, ld);
+			if (oldside == 0 && side == 1)
+			{
+				divline_t dl2 = { ld->v1->x, ld->v1->y, ld->dx, ld->dy };
+				divline_t dl1 = { spec.oldrefpos.x, spec.oldrefpos.y, spec.refpos.x - spec.oldrefpos.x, spec.refpos.y - spec.oldrefpos.y };
+				fixed_t frac = P_InterceptVector(&dl1, &dl2);
+				if (frac < bestfrac)
+				{
+					besthit = spec;
+					bestfrac = frac;
+				}
+			}
+		}
+
+		if (bestfrac < FIXED_MAX)
+		{
+			line_t *ld = besthit.line;
+			FLinePortal *port = ld->getPortal();
+			if (port->mType == PORTT_LINKED)
+			{
+				thing->UnlinkFromWorld();
+				thing->SetXY(tm.x + port->mXDisplacement, tm.y + port->mYDisplacement);
+				thing->PrevX += port->mXDisplacement;
+				thing->PrevY += port->mYDisplacement;
+				thing->LinkToWorld();
+				P_FindFloorCeiling(thing);
+				portalcrossed = true;
+			}
+			else if (!portalcrossed)
+			{
+				line_t *out = port->mDestination;
+				fixedvec3 pos = { tm.x, tm.y, thing->Z() };
+				fixedvec3 oldthingpos = thing->Pos();
+				fixedvec2 thingpos = oldthingpos;
+				
+				P_TranslatePortalXY(ld, out, pos.x, pos.y);
+				P_TranslatePortalXY(ld, out, thingpos.x, thingpos.y);
+				P_TranslatePortalZ(ld, out, pos.z);
+				thing->SetXYZ(thingpos.x, thingpos.y, pos.z);
+				if (!P_CheckPosition(thing, pos.x, pos.y, true))	// check if some actor blocks us on the other side. (No line checks, because of the mess that'd create.)
+				{
+					thing->SetXYZ(oldthingpos);
+					thing->flags6 &= ~MF6_INTRYMOVE;
+					return false;
+				}
+				thing->UnlinkFromWorld();
+				thing->SetXYZ(pos);
+				P_TranslatePortalVXVY(ld, out, thing->velx, thing->vely);
+				P_TranslatePortalAngle(ld, out, thing->angle);
+				thing->LinkToWorld();
+				P_FindFloorCeiling(thing);
+				thing->ClearInterpolation();
+				portalcrossed = true;
+			}
+			// if this is the current camera we need to store the point where the portal was crossed and the exit
+			// so that the renderer can properly calculate an interpolated position along the movement path.
+			if (thing == players[consoleplayer].camera)
+			{
+				divline_t dl1 = { besthit.oldrefpos.x,besthit. oldrefpos.y, besthit.refpos.x - besthit.oldrefpos.x, besthit.refpos.y - besthit.oldrefpos.y };
+				fixedvec3a hit = { dl1.x + FixedMul(dl1.dx, bestfrac), dl1.y + FixedMul(dl1.dy, bestfrac), 0, 0 };
+				line_t *out = port->mDestination;
+
+				R_AddInterpolationPoint(hit);
+				if (port->mType == PORTT_LINKED)
+				{
+					hit.x += port->mXDisplacement;
+					hit.y += port->mYDisplacement;
+				}
+				else
+				{
+					P_TranslatePortalXY(ld, out, hit.x, hit.y);
+					P_TranslatePortalZ(ld, out, hit.z);
+					players[consoleplayer].viewz += hit.z;	// needs to be done here because otherwise the renderer will not catch the change.
+					P_TranslatePortalAngle(ld, out, hit.angle);
+				}
+				R_AddInterpolationPoint(hit);
+			}
+			if (port->mType == PORTT_LINKED) continue;
+		}
+		break;
+	}
+
+
+
+	if (!portalcrossed)
+	{
+		// the move is ok, so link the thing into its new position
+		thing->UnlinkFromWorld();
+
+		oldpos = thing->Pos();
+		oldsector = thing->Sector;
+		thing->floorz = tm.floorz;
+		thing->ceilingz = tm.ceilingz;
+		thing->dropoffz = tm.dropoffz;		// killough 11/98: keep track of dropoffs
+		thing->floorpic = tm.floorpic;
+		thing->floorterrain = tm.floorterrain;
+		thing->floorsector = tm.floorsector;
+		thing->ceilingpic = tm.ceilingpic;
+		thing->ceilingsector = tm.ceilingsector;
+		thing->SetXY(x, y);
+
+		thing->LinkToWorld();
+	}
 
 	if (thing->flags2 & MF2_FLOORCLIP)
 	{
@@ -2161,10 +2398,9 @@ bool P_TryMove(AActor *thing, fixed_t x, fixed_t y,
 		while (spechit.Pop(spec))
 		{
 			line_t *ld = spec.line;
-			fixedvec3 oldrelpos = PosRelative(oldpos, ld, oldsector);
 			// see if the line was crossed
 			side = P_PointOnLineSide(spec.refpos.x, spec.refpos.y, ld);
-			oldside = P_PointOnLineSide(oldrelpos.x, oldrelpos.y, ld);
+			oldside = P_PointOnLineSide(spec.oldrefpos.x, spec.oldrefpos.y, ld);
 			if (side != oldside && ld->special && !(thing->flags6 & MF6_NOTRIGGER))
 			{
 				if (thing->player && (thing->player->cheats & CF_PREDICTING))
@@ -5344,7 +5580,7 @@ void PIT_FloorDrop(AActor *thing, FChangePosition *cpos)
 	}
 	if (thing->player && thing->player->mo == thing)
 	{
-		thing->player->viewz += thing->Z() - oldz;
+		//thing->player->viewz += thing->Z() - oldz;
 	}
 }
 
diff --git a/src/p_maputl.cpp b/src/p_maputl.cpp
index 67c2303e7..057c4329c 100644
--- a/src/p_maputl.cpp
+++ b/src/p_maputl.cpp
@@ -152,7 +152,7 @@ void P_LineOpening (FLineOpening &open, AActor *actor, const line_t *linedef,
 		sector_t *front, *back;
 		fixed_t fc, ff, bc, bf;
 
-		if (linedef->sidedef[1] == NULL)
+		if (linedef->backsector == NULL)
 		{
 			// single sided line
 			open.range = 0;
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index e5da17126..5fdff87e1 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -4045,7 +4045,8 @@ void P_SetupLevel (const char *lumpname, int position)
 
 	times[16].Clock();
 	if (reloop) P_LoopSidedefs (false);
-	PO_Init ();	// Initialize the polyobjs
+	PO_Init ();				// Initialize the polyobjs
+	P_FinalizePortals();	// finalize line portals after polyobjects have been initialized. This info is needed for properly flagging them.
 	times[16].Unclock();
 
 	assert(sidetemp != NULL);
diff --git a/src/p_spec.cpp b/src/p_spec.cpp
index 0496ed1f5..9252abe1d 100644
--- a/src/p_spec.cpp
+++ b/src/p_spec.cpp
@@ -1558,8 +1558,6 @@ void P_SpawnSpecials (void)
 	}
 	// [RH] Start running any open scripts on this map
 	FBehavior::StaticStartTypedScripts (SCRIPT_Open, NULL, false);
-	P_FinalizePortals();
-	P_CreateLinkedPortals();
 }
 
 // killough 2/28/98:
@@ -1888,7 +1886,7 @@ static void P_SpawnScrollers(void)
 
 		switch (special)
 		{
-			register int s;
+			int s;
 
 		case Scroll_Ceiling:
 		{
@@ -2420,7 +2418,7 @@ static void P_SpawnPushers ()
 {
 	int i;
 	line_t *l = lines;
-	register int s;
+	int s;
 
 	for (i = 0; i < numlines; i++, l++)
 	{
diff --git a/src/p_tick.cpp b/src/p_tick.cpp
index 29b2cd4ad..4020bcebe 100644
--- a/src/p_tick.cpp
+++ b/src/p_tick.cpp
@@ -112,6 +112,7 @@ void P_Ticker (void)
 		S_ResumeSound (false);
 
 	P_ResetSightCounters (false);
+	R_ClearInterpolationPath();
 
 	// Since things will be moving, it's okay to interpolate them in the renderer.
 	r_NoInterpolate = false;
diff --git a/src/portal.cpp b/src/portal.cpp
index 2a920f74c..cd501513a 100644
--- a/src/portal.cpp
+++ b/src/portal.cpp
@@ -323,6 +323,12 @@ void P_UpdatePortal(FLinePortal *port)
 		// Portal has no destination: switch it off
 		port->mFlags = 0;
 	}
+	else if ((port->mOrigin->backsector == NULL && !(port->mOrigin->sidedef[0]->Flags & WALLF_POLYOBJ)) ||
+		(port->mDestination->backsector == NULL && !(port->mOrigin->sidedef[0]->Flags & WALLF_POLYOBJ)))
+	{
+		// disable teleporting capability if a portal is or links to a one-sided wall (unless part of a polyobject.)
+		port->mFlags = PORTF_VISIBLE;
+	}
 	else if (port->mDestination->getPortalDestination() != port->mOrigin)
 	{
 		//portal doesn't link back. This will be a simple teleporter portal.
@@ -387,6 +393,7 @@ void P_FinalizePortals()
 	}
 	P_CollectLinkedPortals();
 	BuildBlockmap();
+	P_CreateLinkedPortals();
 }
 
 //============================================================================
diff --git a/src/posix/cocoa/i_system.mm b/src/posix/cocoa/i_system.mm
index 498498d94..07e85281b 100644
--- a/src/posix/cocoa/i_system.mm
+++ b/src/posix/cocoa/i_system.mm
@@ -208,12 +208,12 @@ void I_PrintStr(const char* const message)
 		else if (0x1d == *srcp || 0x1f == *srcp) // Opening and closing bar character
 		{
 			*dstp++ = '-';
-			*srcp++;
+			++srcp;
 		}
 		else if (0x1e == *srcp) // Middle bar character
 		{
 			*dstp++ = '=';
-			*srcp++;
+			++srcp;
 		}
 		else
 		{
diff --git a/src/posix/cocoa/st_console.mm b/src/posix/cocoa/st_console.mm
index e952d22d6..b990b9b33 100644
--- a/src/posix/cocoa/st_console.mm
+++ b/src/posix/cocoa/st_console.mm
@@ -213,7 +213,7 @@ void FConsoleWindow::AddText(const char* message)
 		if (TEXTCOLOR_ESCAPE == *message)
 		{
 			const BYTE* colorID = reinterpret_cast<const BYTE*>(message) + 1;
-			if ('\0' == colorID)
+			if ('\0' == *colorID)
 			{
 				break;
 			}
diff --git a/src/r_defs.h b/src/r_defs.h
index 34ba653e6..088d253d1 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -1401,7 +1401,8 @@ inline void AActor::ClearInterpolation()
 	PrevY = Y();
 	PrevZ = Z();
 	PrevAngle = angle;
-	PrevPortalGroup = Sector->PortalGroup;
+	if (Sector) PrevPortalGroup = Sector->PortalGroup;
+	else PrevPortalGroup = 0;
 }
 
 
diff --git a/src/r_utility.cpp b/src/r_utility.cpp
index 628310fce..0c23064af 100644
--- a/src/r_utility.cpp
+++ b/src/r_utility.cpp
@@ -81,6 +81,7 @@ static TArray<InterpolationViewer> PastViewers;
 static FRandom pr_torchflicker ("TorchFlicker");
 static FRandom pr_hom;
 static bool NoInterpolateView;
+static TArray<fixedvec3a> InterpolationPath;
 
 // PUBLIC DATA DEFINITIONS -------------------------------------------------
 
@@ -574,6 +575,7 @@ void R_InterpolateView (player_t *player, fixed_t frac, InterpolationViewer *ivi
 //	frac = tf;
 	if (NoInterpolateView)
 	{
+		InterpolationPath.Clear();
 		NoInterpolateView = false;
 		iview->oviewx = iview->nviewx;
 		iview->oviewy = iview->nviewy;
@@ -583,10 +585,76 @@ void R_InterpolateView (player_t *player, fixed_t frac, InterpolationViewer *ivi
 	}
 	int oldgroup = R_PointInSubsector(iview->oviewx, iview->oviewy)->sector->PortalGroup;
 	int newgroup = R_PointInSubsector(iview->nviewx, iview->nviewy)->sector->PortalGroup;
-	fixedvec2 disp = Displacements.getOffset(oldgroup, newgroup);
-	viewx = iview->oviewx + FixedMul (frac, iview->nviewx - iview->oviewx - disp.x);
-	viewy = iview->oviewy + FixedMul (frac, iview->nviewy - iview->oviewy - disp.y);
-	viewz = iview->oviewz + FixedMul (frac, iview->nviewz - iview->oviewz);
+
+	fixed_t oviewangle = iview->oviewangle;
+	fixed_t nviewangle = iview->nviewangle;
+	if ((iview->oviewx != iview->nviewx || iview->oviewy != iview->nviewy) && InterpolationPath.Size() > 0)
+	{
+		viewx = iview->nviewx;
+		viewy = iview->nviewy;
+		viewz = iview->nviewz;
+
+		// Interpolating through line portals is a messy affair.
+		// What needs be done is to store the portal transitions of the camera actor as waypoints
+		// and then find out on which part of the path the current view lies.
+		// Needless to say, this doesn't work for chasecam mode.
+		if (!r_showviewer)
+		{
+			fixed_t pathlen = 0;
+			fixed_t zdiff = 0;
+			fixed_t totalzdiff = 0;
+			angle_t adiff = 0;
+			angle_t totaladiff = 0;
+			fixed_t oviewz = iview->oviewz;
+			fixed_t nviewz = iview->nviewz;
+			fixedvec3a oldpos = { iview->oviewx, iview->oviewy, 0, 0 };
+			fixedvec3a newpos = { iview->nviewx, iview->nviewy, 0, 0 };
+			InterpolationPath.Push(newpos);	// add this to  the array to simplify the loops below
+
+			for (unsigned i = 0; i < InterpolationPath.Size(); i += 2)
+			{
+				fixedvec3a &start = i == 0 ? oldpos : InterpolationPath[i - 1];
+				fixedvec3a &end = InterpolationPath[i];
+				pathlen += xs_CRoundToInt(TVector2<double>(end.x - start.x, end.y - start.y).Length());
+				totalzdiff += start.z;
+				totaladiff += start.angle;
+			}
+			fixed_t interpolatedlen = FixedMul(frac, pathlen);
+
+			for (unsigned i = 0; i < InterpolationPath.Size(); i += 2)
+			{
+				fixedvec3a &start = i == 0 ? oldpos : InterpolationPath[i - 1];
+				fixedvec3a &end = InterpolationPath[i];
+				fixed_t fraglen = xs_CRoundToInt(TVector2<double>(end.x - start.x, end.y - start.y).Length());
+				zdiff += start.z;
+				adiff += start.angle;
+				if (fraglen <= interpolatedlen)
+				{
+					interpolatedlen -= fraglen;
+				}
+				else
+				{
+					fixed_t fragfrac = FixedDiv(interpolatedlen, fraglen);
+					oviewz += zdiff;
+					nviewz -= totalzdiff - zdiff;
+					oviewangle += adiff;
+					nviewangle -= totaladiff - adiff;
+					viewx = start.x + FixedMul(fragfrac, end.x - start.x);
+					viewy = start.y + FixedMul(fragfrac, end.y - start.y);
+					viewz = oviewz + FixedMul(frac, nviewz - oviewz);
+					break;
+				}
+			}
+			InterpolationPath.Pop();
+		}
+	}
+	else
+	{
+		fixedvec2 disp = Displacements.getOffset(oldgroup, newgroup);
+		viewx = iview->oviewx + FixedMul(frac, iview->nviewx - iview->oviewx - disp.x);
+		viewy = iview->oviewy + FixedMul(frac, iview->nviewy - iview->oviewy - disp.y);
+		viewz = iview->oviewz + FixedMul(frac, iview->nviewz - iview->oviewz);
+	}
 	if (player != NULL &&
 		!(player->cheats & CF_INTERPVIEW) &&
 		player - players == consoleplayer &&
@@ -602,7 +670,7 @@ void R_InterpolateView (player_t *player, fixed_t frac, InterpolationViewer *ivi
 		(!netgame || !cl_noprediction) &&
 		!LocalKeyboardTurner)
 	{
-		viewangle = iview->nviewangle + (LocalViewAngle & 0xFFFF0000);
+		viewangle = nviewangle + (LocalViewAngle & 0xFFFF0000);
 
 		fixed_t delta = player->centering ? 0 : -(signed)(LocalViewPitch & 0xFFFF0000);
 
@@ -635,7 +703,7 @@ void R_InterpolateView (player_t *player, fixed_t frac, InterpolationViewer *ivi
 	else
 	{
 		viewpitch = iview->oviewpitch + FixedMul (frac, iview->nviewpitch - iview->oviewpitch);
-		viewangle = iview->oviewangle + FixedMul (frac, iview->nviewangle - iview->oviewangle);
+		viewangle = oviewangle + FixedMul (frac, nviewangle - oviewangle);
 	}
 	
 	// Due to interpolation this is not necessarily the same as the sector the camera is in.
@@ -678,6 +746,7 @@ void R_InterpolateView (player_t *player, fixed_t frac, InterpolationViewer *ivi
 
 void R_ResetViewInterpolation ()
 {
+	InterpolationPath.Clear();
 	NoInterpolateView = true;
 }
 
@@ -718,6 +787,7 @@ static InterpolationViewer *FindPastViewer (AActor *actor)
 	InterpolationViewer iview = { NULL, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 	iview.ViewActor = actor;
 	iview.otic = -1;
+	InterpolationPath.Clear();
 	return &PastViewers[PastViewers.Push (iview)];
 }
 
@@ -729,6 +799,7 @@ static InterpolationViewer *FindPastViewer (AActor *actor)
 
 void R_FreePastViewers ()
 {
+	InterpolationPath.Clear();
 	PastViewers.Clear ();
 }
 
@@ -742,6 +813,7 @@ void R_FreePastViewers ()
 
 void R_ClearPastViewer (AActor *actor)
 {
+	InterpolationPath.Clear();
 	for (unsigned int i = 0; i < PastViewers.Size(); ++i)
 	{
 		if (PastViewers[i].ViewActor == actor)
@@ -781,6 +853,7 @@ void R_RebuildViewInterpolation(player_t *player)
 	iview->oviewz = iview->nviewz;
 	iview->oviewpitch = iview->nviewpitch;
 	iview->oviewangle = iview->nviewangle;
+	InterpolationPath.Clear();
 }
 
 //==========================================================================
@@ -794,6 +867,29 @@ bool R_GetViewInterpolationStatus()
 	return NoInterpolateView;
 }
 
+
+//==========================================================================
+//
+// R_ClearInterpolationPath
+//
+//==========================================================================
+
+void R_ClearInterpolationPath()
+{
+	InterpolationPath.Clear();
+}
+
+//==========================================================================
+//
+// R_AddInterpolationPoint
+//
+//==========================================================================
+
+void R_AddInterpolationPoint(const fixedvec3a &vec)
+{
+	InterpolationPath.Push(vec);
+}
+
 //==========================================================================
 //
 // QuakePower
diff --git a/src/r_utility.h b/src/r_utility.h
index 10dcf5352..f8f91c1bc 100644
--- a/src/r_utility.h
+++ b/src/r_utility.h
@@ -63,11 +63,21 @@ inline angle_t R_PointToAnglePrecise (fixed_t viewx, fixed_t viewy, fixed_t x, f
 	return xs_RoundToUInt(atan2(double(y-viewy), double(x-viewx)) * (ANGLE_180/M_PI));
 }
 
+// Used for interpolation waypoints.
+struct fixedvec3a
+{
+	fixed_t x, y, z;
+	angle_t angle;
+};
+
+
 subsector_t *R_PointInSubsector (fixed_t x, fixed_t y);
 fixed_t R_PointToDist2 (fixed_t dx, fixed_t dy);
 void R_ResetViewInterpolation ();
 void R_RebuildViewInterpolation(player_t *player);
 bool R_GetViewInterpolationStatus();
+void R_ClearInterpolationPath();
+void R_AddInterpolationPoint(const fixedvec3a &vec);
 void R_SetViewSize (int blocks);
 void R_SetFOV (float fov);
 float R_GetFOV ();
diff --git a/src/tarray.h b/src/tarray.h
index d62d75e28..63d693261 100644
--- a/src/tarray.h
+++ b/src/tarray.h
@@ -50,6 +50,23 @@
 
 class FArchive;
 
+
+template<typename T> class TIterator
+{
+public:
+	TIterator(T* ptr = nullptr) { m_ptr = ptr; }
+	bool operator==(const TIterator<T>& other) const { return (m_ptr == other.m_ptr); }
+	bool operator!=(const TIterator<T>& other) const { return (m_ptr != other.m_ptr); }
+	TIterator<T> &operator++() { ++m_ptr; return (*this); }
+	T &operator*() { return *m_ptr; }
+	const T &operator*() const { return *m_ptr; }
+	T* operator->() { return m_ptr; }
+
+protected:
+	T* m_ptr;
+};
+
+
 // TArray -------------------------------------------------------------------
 
 // Must match TArray's layout.
@@ -68,6 +85,32 @@ class TArray
 	template<class U, class UU> friend FArchive &operator<< (FArchive &arc, TArray<U,UU> &self);
 
 public:
+
+    typedef TIterator<T>                       iterator;
+    typedef TIterator<const T>                 const_iterator;
+
+    iterator begin()
+	{
+		return &Array[0];
+	}
+
+	iterator end()
+	{
+		return &Array[Count];
+	}
+	
+	const_iterator cbegin() const
+	{
+		return &Array[0];
+	}
+	
+	const_iterator cend() const
+	{
+		return &Array[Count];
+	}
+	
+	
+
 	////////
 	// This is a dummy constructor that does nothing. The purpose of this
 	// is so you can create a global TArray in the data segment that gets
diff --git a/src/thingdef/thingdef_exp.h b/src/thingdef/thingdef_exp.h
index 62640e7e1..daa824264 100644
--- a/src/thingdef/thingdef_exp.h
+++ b/src/thingdef/thingdef_exp.h
@@ -841,7 +841,7 @@ class FxFlopFunctionCall : public FxExpression
 
 public:
 
-	FxFlopFunctionCall(int index, FArgumentList *args, const FScriptPosition &pos);
+	FxFlopFunctionCall(size_t index, FArgumentList *args, const FScriptPosition &pos);
 	~FxFlopFunctionCall();
 	FxExpression *Resolve(FCompileContext&);
 	ExpEmit Emit(VMFunctionBuilder *build);
diff --git a/src/thingdef/thingdef_expression.cpp b/src/thingdef/thingdef_expression.cpp
index 2ac41f7a8..b5b35a770 100644
--- a/src/thingdef/thingdef_expression.cpp
+++ b/src/thingdef/thingdef_expression.cpp
@@ -3176,7 +3176,7 @@ FxFunctionCall::~FxFunctionCall()
 
 FxExpression *FxFunctionCall::Resolve(FCompileContext& ctx)
 {
-	for (int i = 0; i < countof(FxFlops); ++i)
+	for (size_t i = 0; i < countof(FxFlops); ++i)
 	{
 		if (MethodName == FxFlops[i].Name)
 		{
@@ -3514,10 +3514,10 @@ ExpEmit FxVMFunctionCall::Emit(VMFunctionBuilder *build, bool tailcall)
 //
 //==========================================================================
 
-FxFlopFunctionCall::FxFlopFunctionCall(int index, FArgumentList *args, const FScriptPosition &pos)
+FxFlopFunctionCall::FxFlopFunctionCall(size_t index, FArgumentList *args, const FScriptPosition &pos)
 : FxExpression(pos)
 {
-	assert(index >= 0 && index < countof(FxFlops) && "FLOP index out of range");
+	assert(index < countof(FxFlops) && "FLOP index out of range");
 	Index = index;
 	ArgList = args;
 }