diff --git a/src/actor.h b/src/actor.h
index 4deb349a78..96e4248632 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -1360,6 +1360,14 @@ inline T *Spawn (const fixedvec3 &pos, replace_t allowreplacement)
 	return static_cast<T *>(AActor::StaticSpawn (RUNTIME_CLASS(T), pos.x, pos.y, pos.z, allowreplacement));
 }
 
+inline fixedvec2 Vec2Angle(fixed_t length, angle_t angle) 
+{
+	fixedvec2 ret = { FixedMul(length, finecosine[angle >> ANGLETOFINESHIFT]),
+						FixedMul(length, finesine[angle >> ANGLETOFINESHIFT]) };
+	return ret;
+}
+
+
 void PrintMiscActorInfo(AActor * query);
 
 #define S_FREETARGMOBJ	1
diff --git a/src/g_doom/a_bossbrain.cpp b/src/g_doom/a_bossbrain.cpp
index a99ef93239..65d9d08b4d 100644
--- a/src/g_doom/a_bossbrain.cpp
+++ b/src/g_doom/a_bossbrain.cpp
@@ -55,9 +55,9 @@ DEFINE_ACTION_FUNCTION(AActor, A_BrainScream)
 {
 	fixed_t x;
 		
-	for (x = self->x - 196*FRACUNIT; x < self->x + 320*FRACUNIT; x += 8*FRACUNIT)
+	for (x = self->X() - 196*FRACUNIT; x < self->X() + 320*FRACUNIT; x += 8*FRACUNIT)
 	{
-		BrainishExplosion (x, self->y - 320*FRACUNIT,
+		BrainishExplosion (x, self->Y() - 320*FRACUNIT,
 			128 + (pr_brainscream() << (FRACBITS + 1)));
 	}
 	S_Sound (self, CHAN_VOICE, "brain/death", 1, ATTN_NONE);
@@ -65,9 +65,9 @@ DEFINE_ACTION_FUNCTION(AActor, A_BrainScream)
 
 DEFINE_ACTION_FUNCTION(AActor, A_BrainExplode)
 {
-	fixed_t x = self->x + pr_brainexplode.Random2()*2048;
+	fixed_t x = self->X() + pr_brainexplode.Random2()*2048;
 	fixed_t z = 128 + pr_brainexplode()*2*FRACUNIT;
-	BrainishExplosion (x, self->y, z);
+	BrainishExplosion (x, self->Y(), z);
 }
 
 DEFINE_ACTION_FUNCTION(AActor, A_BrainDie)
@@ -140,11 +140,11 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_BrainSpit)
 			}
 			else if (abs(spit->vely) > abs(spit->velx))
 			{
-				spit->special2 = (targ->y - self->y) / spit->vely;
+				spit->special2 = (targ->Y() - self->Y()) / spit->vely;
 			}
 			else
 			{
-				spit->special2 = (targ->x - self->x) / spit->velx;
+				spit->special2 = (targ->X() - self->X()) / spit->velx;
 			}
 			// [GZ] Calculates when the projectile will have reached destination
 			spit->special2 += level.maptime;
@@ -185,7 +185,7 @@ static void SpawnFly(AActor *self, const PClass *spawntype, FSoundID sound)
 	
 	if (spawntype != NULL)
 	{
-		fog = Spawn (spawntype, targ->x, targ->y, targ->z, ALLOW_REPLACE);
+		fog = Spawn (spawntype, targ->X(), targ->Y(), targ->Z(), ALLOW_REPLACE);
 		if (fog != NULL) S_Sound (fog, CHAN_BODY, sound, 1, ATTN_NORM);
 	}
 
@@ -256,7 +256,7 @@ static void SpawnFly(AActor *self, const PClass *spawntype, FSoundID sound)
 	spawntype = PClass::FindClass(SpawnName);
 	if (spawntype != NULL)
 	{
-		newmobj = Spawn (spawntype, targ->x, targ->y, targ->z, ALLOW_REPLACE);
+		newmobj = Spawn (spawntype, targ->X(), targ->Y(), targ->Z(), ALLOW_REPLACE);
 		if (newmobj != NULL)
 		{
 			// Make the new monster hate what the boss eye hates
@@ -275,7 +275,7 @@ static void SpawnFly(AActor *self, const PClass *spawntype, FSoundID sound)
 			if (!(newmobj->ObjectFlags & OF_EuthanizeMe))
 			{
 				// telefrag anything in this spot
-				P_TeleportMove (newmobj, newmobj->x, newmobj->y, newmobj->z, true);
+				P_TeleportMove (newmobj, newmobj->X(), newmobj->Y(), newmobj->Z(), true);
 			}
 			newmobj->flags4 |= MF4_BOSSSPAWNED;
 		}
diff --git a/src/g_doom/a_doomweaps.cpp b/src/g_doom/a_doomweaps.cpp
index 79dd6253f7..85335587e7 100644
--- a/src/g_doom/a_doomweaps.cpp
+++ b/src/g_doom/a_doomweaps.cpp
@@ -612,8 +612,8 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_BFGSpray)
 
 		if (linetarget != NULL)
 		{
-			AActor *spray = Spawn(spraytype, linetarget->x, linetarget->y,
-				linetarget->z + (linetarget->height >> 2), ALLOW_REPLACE);
+			AActor *spray = Spawn(spraytype, linetarget->X(), linetarget->Y(),
+				linetarget->Z() + (linetarget->height >> 2), ALLOW_REPLACE);
 
 			int dmgFlags = 0;
 			FName dmgType = NAME_BFGSplash;
diff --git a/src/g_doom/a_fatso.cpp b/src/g_doom/a_fatso.cpp
index 066e60468c..c9f53d9d3e 100644
--- a/src/g_doom/a_fatso.cpp
+++ b/src/g_doom/a_fatso.cpp
@@ -145,7 +145,7 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_Mushroom)
 	P_CheckSplash(self, 128<<FRACBITS);
 
 	// Now launch mushroom cloud
-	AActor *target = Spawn("Mapspot", 0, 0, 0, NO_REPLACE);	// We need something to aim at.
+	AActor *target = Spawn("Mapspot", self->X(), self->Y(), self->Z(), NO_REPLACE);	// We need something to aim at.
 	AActor *master = (flags & MSF_DontHurt) ? (AActor*)(self->target) : self;
 	target->height = self->height;
  	for (i = -n; i <= n; i += 8)
@@ -153,9 +153,9 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_Mushroom)
  		for (j = -n; j <= n; j += 8)
 		{
 			AActor *mo;
-			target->x = self->x + (i << FRACBITS);    // Aim in many directions from source
-			target->y = self->y + (j << FRACBITS);
-			target->z = self->z + (P_AproxDistance(i,j) * vrange); // Aim up fairly high
+			target->x = self->X() + (i << FRACBITS);    // Aim in many directions from source
+			target->y = self->Y() + (j << FRACBITS);
+			target->z = self->Z() + (P_AproxDistance(i,j) * vrange); // Aim up fairly high
 			if ((flags & MSF_Classic) || // Flag explicitely set, or no flags and compat options
 				(flags == 0 && (self->state->DefineFlags & SDF_DEHACKED) && (i_compatflags & COMPATF_MUSHROOM)))
 			{	// Use old function for MBF compatibility
diff --git a/src/g_doom/a_lostsoul.cpp b/src/g_doom/a_lostsoul.cpp
index 1182292e00..7dc9a1b8f9 100644
--- a/src/g_doom/a_lostsoul.cpp
+++ b/src/g_doom/a_lostsoul.cpp
@@ -41,7 +41,7 @@ void A_SkullAttack(AActor *self, fixed_t speed)
 	
 	if (dist < 1)
 		dist = 1;
-	self->velz = (dest->z + (dest->height>>1) - self->z) / dist;
+	self->velz = (dest->Z() + (dest->height>>1) - self->Z()) / dist;
 }
 
 DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SkullAttack)
diff --git a/src/g_doom/a_painelemental.cpp b/src/g_doom/a_painelemental.cpp
index f361fb78d0..cb5205a762 100644
--- a/src/g_doom/a_painelemental.cpp
+++ b/src/g_doom/a_painelemental.cpp
@@ -35,17 +35,14 @@ enum PA_Flags
 //
 void A_PainShootSkull (AActor *self, angle_t angle, const PClass *spawntype, int flags = 0, int limit = -1)
 {
-	fixed_t x, y, z;
-	
 	AActor *other;
-	angle_t an;
 	int prestep;
 
 	if (spawntype == NULL) return;
 	if (self->DamageType==NAME_Massacre) return;
 
 	// [RH] check to make sure it's not too close to the ceiling
-	if (self->z + self->height + 8*FRACUNIT > self->ceilingz)
+	if (self->Top() + 8*FRACUNIT > self->ceilingz)
 	{
 		if (self->flags & MF_FLOAT)
 		{
@@ -76,47 +73,67 @@ void A_PainShootSkull (AActor *self, angle_t angle, const PClass *spawntype, int
 	}
 
 	// okay, there's room for another one
-	an = angle >> ANGLETOFINESHIFT;
-	
 	prestep = 4*FRACUNIT +
 		3*(self->radius + GetDefaultByType(spawntype)->radius)/2;
-	
-	x = self->x + FixedMul (prestep, finecosine[an]);
-	y = self->y + FixedMul (prestep, finesine[an]);
-	z = self->z + 8*FRACUNIT;
-				
-	// Check whether the Lost Soul is being fired through a 1-sided	// phares
-	// wall or an impassible line, or a "monsters can't cross" line.//   |
-	// If it is, then we don't allow the spawn.						//   V
 
-	FBoundingBox box(MIN(self->x, x), MIN(self->y, y), MAX(self->x, x), MAX(self->y, y));
-	FBlockLinesIterator it(box);
-	line_t *ld;
+	// NOTE: The following code contains some advance work for line-to-line portals which is currenty inactive.
 
-	while ((ld = it.Next()))
+	fixedvec2 dist = Vec2Angle(prestep, angle);
+	fixedvec3 pos = self->Vec3Offset(dist.x, dist.y, 8 * FRACUNIT, true);
+	fixedvec3 src = { self->X(), self->Y(), self->Z() };
+
+	for (int i = 0; i < 2; i++)
 	{
-		if (!(ld->flags & ML_TWOSIDED) ||
-			(ld->flags & (ML_BLOCKING|ML_BLOCKMONSTERS|ML_BLOCKEVERYTHING)))
+		// Check whether the Lost Soul is being fired through a 1-sided	// phares
+		// wall or an impassible line, or a "monsters can't cross" line.//   |
+		// If it is, then we don't allow the spawn.						//   V
+
+		FBoundingBox box(MIN(src.x, pos.x), MIN(src.y, pos.y), MAX(src.x, pos.x), MAX(src.y, pos.y));
+		FBlockLinesIterator it(box);
+		line_t *ld;
+		bool inportal = false;
+
+		while ((ld = it.Next()))
 		{
-			if (!(box.Left()   > ld->bbox[BOXRIGHT]  ||
-				  box.Right()  < ld->bbox[BOXLEFT]   ||
-				  box.Top()    < ld->bbox[BOXBOTTOM] ||
-				  box.Bottom() > ld->bbox[BOXTOP]))
+			if (ld->isLinePortal() && i == 0)
 			{
-				if (P_PointOnLineSidePrecise(self->x,self->y,ld) != P_PointOnLineSidePrecise(x,y,ld))
-					return;  // line blocks trajectory				//   ^
+				if (P_PointOnLineSidePrecise(src.x, src.y, ld) == 0 &&
+					P_PointOnLineSidePrecise(pos.x, pos.y, ld) == 1)
+				{
+					// crossed a portal line from front to back, we need to repeat the check on the other side as well.
+					inportal = true;
+				}
+			}
+			else if (!(ld->flags & ML_TWOSIDED) ||
+				(ld->flags & (ML_BLOCKING | ML_BLOCKMONSTERS | ML_BLOCKEVERYTHING)))
+			{
+				if (!(box.Left() > ld->bbox[BOXRIGHT] ||
+					box.Right() < ld->bbox[BOXLEFT] ||
+					box.Top() < ld->bbox[BOXBOTTOM] ||
+					box.Bottom() > ld->bbox[BOXTOP]))
+				{
+					if (P_PointOnLineSidePrecise(src.x, src.y, ld) != P_PointOnLineSidePrecise(pos.x, pos.y, ld))
+						return;  // line blocks trajectory				//   ^
+				}
 			}
 		}
+		if (!inportal) break;
+
+		// recalculate position and redo the check on the other side of the portal
+		pos = self->Vec3Offset(dist.x, dist.y, 8 * FRACUNIT, false);
+		src.x = pos.x - dist.x;
+		src.y = pos.y - dist.y;
+
 	}
 
-	other = Spawn (spawntype, x, y, z, ALLOW_REPLACE);
+	other = Spawn (spawntype, pos.x, pos.y, pos.z, ALLOW_REPLACE);
 
 	// Check to see if the new Lost Soul's z value is above the
 	// ceiling of its new sector, or below the floor. If so, kill it.
 
-	if ((other->z >
-         (other->Sector->ceilingplane.ZatPoint (other->x, other->y) - other->height)) ||
-        (other->z < other->Sector->floorplane.ZatPoint (other->x, other->y)))
+	if ((other->Z() >
+         (other->Sector->HighestCeiling(other) - other->height)) ||
+        (other->Z() < other->Sector->LowestFloor(other)))
 	{
 		// kill it immediately
 		P_DamageMobj (other, self, self, TELEFRAG_DAMAGE, NAME_None);//  ^
@@ -125,7 +142,7 @@ void A_PainShootSkull (AActor *self, angle_t angle, const PClass *spawntype, int
 
 	// Check for movements.
 
-	if (!P_CheckPosition (other, other->x, other->y))
+	if (!P_CheckPosition (other, other->X(), other->Y()))
 	{
 		// kill it immediately
 		P_DamageMobj (other, self, self, TELEFRAG_DAMAGE, NAME_None);		
diff --git a/src/g_heretic/a_dsparil.cpp b/src/g_heretic/a_dsparil.cpp
index e4d86c83af..b12be80810 100644
--- a/src/g_heretic/a_dsparil.cpp
+++ b/src/g_heretic/a_dsparil.cpp
@@ -254,10 +254,10 @@ DEFINE_ACTION_FUNCTION(AActor, A_GenWizard)
 {
 	AActor *mo;
 
-	mo = Spawn("Wizard", self->x, self->y, self->z, ALLOW_REPLACE);
+	mo = Spawn("Wizard", self->X(), self->Y(), self->Z(), ALLOW_REPLACE);
 	if (mo != NULL)
 	{
-		mo->z -= mo->GetDefault()->height/2;
+		mo->SetZ(mo->Z() - mo->GetDefault()->height / 2, false);
 		if (!P_TestMobjLocation (mo))
 		{ // Didn't fit
 			mo->ClearCounters();
@@ -272,7 +272,7 @@ DEFINE_ACTION_FUNCTION(AActor, A_GenWizard)
 			self->flags &= ~MF_MISSILE;
 			mo->master = self->target;
 			// Heretic did not offset it by TELEFOGHEIGHT, so I won't either.
-			Spawn<ATeleportFog> (self->x, self->y, self->z, ALLOW_REPLACE);
+			Spawn<ATeleportFog> (self->X(), self->Y(), self->Z(), ALLOW_REPLACE);
 		}
 	}
 }
diff --git a/src/r_defs.h b/src/r_defs.h
index dd8496e4d9..4f0b5ed01c 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -683,6 +683,17 @@ struct sector_t
 		return pos == floor? floorplane:ceilingplane;
 	}
 
+	fixed_t HighestCeiling(AActor *a) const
+	{
+		return ceilingplane.ZatPoint(a);
+	}
+
+	fixed_t LowestFloor(AActor *a) const
+	{
+		return floorplane.ZatPoint(a);
+	}
+
+
 	bool isSecret() const
 	{
 		return !!(Flags & SECF_SECRET);
@@ -977,6 +988,11 @@ struct line_t
 	sector_t	*frontsector, *backsector;
 	int 		validcount;	// if == validcount, already checked
 	int			locknumber;	// [Dusk] lock number for special
+
+	bool isLinePortal() const
+	{
+		return false;
+	}
 };
 
 // phares 3/14/98