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..960c82f47 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -969,12 +969,14 @@ 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)
 	{
 		spec.line = ld;
 		spec.refpos = cres.position;
+		spec.oldrefpos = tm.thing->PosRelative(ld);
 		portalhit.Push(spec);
 	}
 
@@ -1526,7 +1528,6 @@ 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;
@@ -1604,6 +1605,8 @@ bool P_CheckPosition(AActor *thing, fixed_t x, fixed_t y, FCheckPosition &tm, bo
 	// a pickup they cannot get, because their validcount will prevent them from
 	// being considered for collision with the player.
 	validcount++;
+	spechit.Clear();
+	portalhit.Clear();
 
 	thing->BlockingMobj = NULL;
 	thing->height = realheight;
@@ -2132,22 +2135,125 @@ 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 = false;
 
-	thing->LinkToWorld();
+	while (true)
+	{
+		fixed_t bestfrac = FIXED_MAX;
+		spechit_t *besthit = NULL;
+		// 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;
+				
+				// This gets a bit tricky because we want to catch all line specials the actor crosses on the other side, too.
+				// So we have to translate the old Actor xy and temporarily set this as the actor's current position for the P_CheckPosition call,
+				// so that the spechit array gets proper positions assigned that can be evaluated later.
+				P_TranslatePortalXY(ld, out, pos.x, pos.y);
+				P_TranslatePortalXY(ld, out, thingpos.x, thingpos.y);
+				P_TranslatePortalVXVY(ld, out, thing->velx, thing->vely);
+				P_TranslatePortalAngle(ld, out, thing->angle);
+				P_TranslatePortalZ(ld, out, pos.z);
+				thing->SetXYZ(thingpos.x, thingpos.y, pos.z);
+				if (!P_CheckPosition(thing, pos.x, pos.y))
+				{
+					thing->SetXYZ(oldthingpos);
+					thing->flags6 &= ~MF6_INTRYMOVE;
+					return false;
+				}
+				thing->UnlinkFromWorld();
+				thing->SetXYZ(pos);
+				thing->LinkToWorld();
+				P_FindFloorCeiling(thing);
+				thing->ClearInterpolation();
+			}
+			// 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 };
+				fixedvec3 hit = { dl1.x + FixedMul(dl1.dx, bestfrac), dl1.y + FixedMul(dl1.dy, bestfrac), 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);
+				}
+				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 +2267,9 @@ 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))
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/r_utility.cpp b/src/r_utility.cpp
index 628310fce..0239aaa5d 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<fixedvec3> 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 +585,67 @@ 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);
+
+	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;
+			fixed_t oviewz = iview->oviewz;
+			fixed_t nviewz = iview->nviewz;
+			fixedvec3 oldpos = { iview->oviewx, iview->oviewy, 0 };
+			fixedvec3 newpos = { iview->nviewx, iview->nviewy, 0 };
+			InterpolationPath.Push(newpos);	// add this to  the array to simplify the loops below
+
+			for (unsigned i = 0; i < InterpolationPath.Size(); i += 2)
+			{
+				fixedvec3 &start = i == 0 ? oldpos : InterpolationPath[i - 1];
+				fixedvec3 &end = InterpolationPath[i];
+				pathlen += xs_CRoundToInt(TVector2<double>(end.x - start.x, end.y - start.y).Length());
+				totalzdiff += start.z;
+			}
+			fixed_t interpolatedlen = FixedMul(frac, pathlen);
+
+			for (unsigned i = 0; i < InterpolationPath.Size(); i += 2)
+			{
+				fixedvec3 &start = i == 0 ? oldpos : InterpolationPath[i - 1];
+				fixedvec3 &end = InterpolationPath[i];
+				fixed_t fraglen = xs_CRoundToInt(TVector2<double>(end.x - start.x, end.y - start.y).Length());
+				zdiff += start.z;
+				if (fraglen <= interpolatedlen)
+				{
+					interpolatedlen -= fraglen;
+				}
+				else
+				{
+					fixed_t fragfrac = FixedDiv(interpolatedlen, fraglen);
+					oviewz += zdiff;
+					nviewz -= totalzdiff - zdiff;
+					viewx = start.x + FixedMul(fragfrac, end.x - start.x);
+					viewy = start.y + FixedMul(fragfrac, end.y - start.y);
+					viewz = oviewz + FixedMul(frac, nviewz - oviewz);
+				}
+			}
+			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 &&
@@ -678,6 +737,7 @@ void R_InterpolateView (player_t *player, fixed_t frac, InterpolationViewer *ivi
 
 void R_ResetViewInterpolation ()
 {
+	InterpolationPath.Clear();
 	NoInterpolateView = true;
 }
 
@@ -718,6 +778,7 @@ 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 +790,7 @@ static InterpolationViewer *FindPastViewer (AActor *actor)
 
 void R_FreePastViewers ()
 {
+	InterpolationPath.Clear();
 	PastViewers.Clear ();
 }
 
@@ -742,6 +804,7 @@ 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 +844,7 @@ void R_RebuildViewInterpolation(player_t *player)
 	iview->oviewz = iview->nviewz;
 	iview->oviewpitch = iview->nviewpitch;
 	iview->oviewangle = iview->nviewangle;
+	InterpolationPath.Clear();
 }
 
 //==========================================================================
@@ -794,6 +858,29 @@ bool R_GetViewInterpolationStatus()
 	return NoInterpolateView;
 }
 
+
+//==========================================================================
+//
+// R_ClearInterpolationPath
+//
+//==========================================================================
+
+void R_ClearInterpolationPath()
+{
+	InterpolationPath.Clear();
+}
+
+//==========================================================================
+//
+// R_AddInterpolationPoint
+//
+//==========================================================================
+
+void R_AddInterpolationPoint(const fixedvec3 &vec)
+{
+	InterpolationPath.Push(vec);
+}
+
 //==========================================================================
 //
 // QuakePower
diff --git a/src/r_utility.h b/src/r_utility.h
index 10dcf5352..e9efb14e9 100644
--- a/src/r_utility.h
+++ b/src/r_utility.h
@@ -68,6 +68,8 @@ 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 fixedvec3 &vec);
 void R_SetViewSize (int blocks);
 void R_SetFOV (float fov);
 float R_GetFOV ();