diff --git a/src/gl/data/gl_data.h b/src/gl/data/gl_data.h
index c8067b3ba..1e93f9a28 100644
--- a/src/gl/data/gl_data.h
+++ b/src/gl/data/gl_data.h
@@ -51,7 +51,7 @@ struct FPortal
 	int plane;
 	GLSectorStackPortal *glportal;	// for quick access to the render data. This is only valid during BSP traversal!
 
-	GLSectorStackPortal *GetGLPortal();
+	GLSectorStackPortal *GetRenderState();
 };
 
 struct FGLLinePortal
@@ -68,7 +68,7 @@ extern TArray<FGLLinePortal*> linePortalToGL;
 extern TArray<BYTE> currentmapsection;
 
 void gl_InitPortals();
-void gl_BuildPortalCoverage(FPortalCoverage *coverage, subsector_t *subsector, FPortal *portal);
+void gl_BuildPortalCoverage(FPortalCoverage *coverage, subsector_t *subsector, const DVector2 &displacement);
 void gl_InitData();
 
 extern long gl_frameMS;
diff --git a/src/gl/data/gl_portaldata.cpp b/src/gl/data/gl_portaldata.cpp
index 98e19c80e..413c85dc6 100644
--- a/src/gl/data/gl_portaldata.cpp
+++ b/src/gl/data/gl_portaldata.cpp
@@ -94,7 +94,7 @@ TArray<FGLLinePortal> glLinePortals;
 //
 //==========================================================================
 
-GLSectorStackPortal *FPortal::GetGLPortal()
+GLSectorStackPortal *FPortal::GetRenderState()
 {
 	if (glportal == NULL) glportal = new GLSectorStackPortal(this);
 	return glportal;
@@ -125,7 +125,6 @@ struct FCoverageLine
 struct FCoverageBuilder
 {
 	subsector_t *target;
-	FPortal *portal;
 	TArray<int> collect;
 	FCoverageVertex center;
 
@@ -135,10 +134,9 @@ struct FCoverageBuilder
 	//
 	//==========================================================================
 
-	FCoverageBuilder(subsector_t *sub, FPortal *port)
+	FCoverageBuilder(subsector_t *sub)
 	{
 		target = sub;
-		portal = port;
 	}
 
 	//==========================================================================
@@ -322,7 +320,7 @@ struct FCoverageBuilder
 //
 //==========================================================================
 
-void gl_BuildPortalCoverage(FPortalCoverage *coverage, subsector_t *subsector, FPortal *portal)
+void gl_BuildPortalCoverage(FPortalCoverage *coverage, subsector_t *subsector, const DVector2 &displacement)
 {
 	TArray<FCoverageVertex> shape;
 	double centerx=0, centery=0;
@@ -330,11 +328,11 @@ void gl_BuildPortalCoverage(FPortalCoverage *coverage, subsector_t *subsector, F
 	shape.Resize(subsector->numlines);
 	for(unsigned i=0; i<subsector->numlines; i++)
 	{
-		centerx += (shape[i].x = FLOAT2FIXED(subsector->firstline[i].v1->fX() + portal->mDisplacement.X));
-		centery += (shape[i].y = FLOAT2FIXED(subsector->firstline[i].v1->fY() + portal->mDisplacement.Y));
+		centerx += (shape[i].x = FLOAT2FIXED(subsector->firstline[i].v1->fX() + displacement.X));
+		centery += (shape[i].y = FLOAT2FIXED(subsector->firstline[i].v1->fY() + displacement.Y));
 	}
 
-	FCoverageBuilder build(subsector, portal);
+	FCoverageBuilder build(subsector);
 	build.center.x = xs_CRoundToInt(centerx / subsector->numlines);
 	build.center.y = xs_CRoundToInt(centery / subsector->numlines);
 
@@ -357,10 +355,10 @@ static void CollectPortalSectors(FPortalMap &collection)
 		sector_t *sec = &sectors[i];
 		for (int j = 0; j < 2; j++)
 		{
-			ASkyViewpoint *SkyBox = barrier_cast<ASkyViewpoint*>(sec->SkyBoxes[j]);
-			if (SkyBox != NULL && SkyBox->bAlways && SkyBox->Mate != NULL)
+			int ptype = sec->GetPortalType(j);
+			if (ptype== SKYBOX_STACKEDSECTORTHING || ptype == SKYBOX_PORTAL || ptype == SKYBOX_LINKEDPORTAL)	// only offset-displacing portal types
 			{
-				FPortalID id = { {SkyBox->X() - SkyBox->Mate->X(), SkyBox->Y() - SkyBox->Mate->Y()} };
+				FPortalID id = { sec->GetPortalDisplacement(j) };
 
 				FPortalSectors &sss = collection[id];
 				FPortalSector ss = { sec, j };
@@ -401,8 +399,7 @@ void gl_InitPortals()
 		}
 		for (int i=1;i<=2;i<<=1)
 		{
-			// For now, add separate portals for floor and ceiling. They can be merged once
-			// proper plane clipping is in.
+			// add separate portals for floor and ceiling.
 			if (planeflags & i)
 			{
 				FPortal *portal = new FPortal;
@@ -419,7 +416,7 @@ void gl_InitPortals()
 						for(int k=0;k<sec->subsectorcount; k++)
 						{
 							subsector_t *sub = sec->subsectors[k];
-							gl_BuildPortalCoverage(&sub->portalcoverage[plane], sub, portal);
+							gl_BuildPortalCoverage(&sub->portalcoverage[plane], sub, pair->Key.mDisplacement);
 						}
 						sec->portals[plane] = portal;
 					}
@@ -511,13 +508,13 @@ CCMD(dumpportals)
 		for(int j=0;j<numsubsectors;j++)
 		{
 			subsector_t *sub = &subsectors[j];
-			FPortal *port = sub->render_sector->portals[portals[i]->plane];
+			FPortal *port = sub->render_sector->GetGLPortal(portals[i]->plane);
 			if (port == portals[i])
 			{
 				Printf(PRINT_LOG, "\tSubsector %d (%d):\n\t\t", j, sub->render_sector->sectornum);
 				for(unsigned k = 0;k< sub->numlines; k++)
 				{
-					Printf(PRINT_LOG, "(%.3f,%.3f), ",	sub->firstline[k].v1->fixX()/65536. + xdisp, sub->firstline[k].v1->fixY()/65536. + ydisp);
+					Printf(PRINT_LOG, "(%.3f,%.3f), ",	sub->firstline[k].v1->fX() + xdisp, sub->firstline[k].v1->fY() + ydisp);
 				}
 				Printf(PRINT_LOG, "\n\t\tCovered by subsectors:\n");
 				FPortalCoverage *cov = &sub->portalcoverage[portals[i]->plane];
@@ -527,7 +524,7 @@ CCMD(dumpportals)
 					Printf(PRINT_LOG, "\t\t\t%5d (%4d): ", cov->subsectors[l], csub->render_sector->sectornum);
 					for(unsigned m = 0;m< csub->numlines; m++)
 					{
-						Printf(PRINT_LOG, "(%.3f,%.3f), ",	csub->firstline[m].v1->fixX()/65536., csub->firstline[m].v1->fixY()/65536.);
+						Printf(PRINT_LOG, "(%.3f,%.3f), ",	csub->firstline[m].v1->fX(), csub->firstline[m].v1->fY());
 					}
 					Printf(PRINT_LOG, "\n");
 				}
diff --git a/src/gl/dynlights/a_dynlight.cpp b/src/gl/dynlights/a_dynlight.cpp
index 032551e4f..36382ce36 100644
--- a/src/gl/dynlights/a_dynlight.cpp
+++ b/src/gl/dynlights/a_dynlight.cpp
@@ -591,24 +591,23 @@ void ADynamicLight::CollectWithinRadius(const DVector3 &pos, subsector_t *subSec
 			}
 		}
 	}
-	if (!subSec->sector->PortalBlocksSight(sector_t::ceiling))
+	sector_t *sec = subSec->sector;
+	if (!sec->PortalBlocksSight(sector_t::ceiling))
 	{
 		line_t *other = subSec->firstline->linedef;
-		AActor *sb = subSec->sector->SkyBoxes[sector_t::ceiling];
-		if (sb->specialf1 < Z() + radius)
+		if (sec->GetPortalPlaneZ(sector_t::ceiling) < Z() + radius)
 		{
-			DVector2 refpos = other->v1->fPos() + other->Delta() / 2 + sb->Scale;
+			DVector2 refpos = other->v1->fPos() + other->Delta() / 2 + sec->GetPortalDisplacement(sector_t::ceiling);
 			subsector_t *othersub = R_PointInSubsector(refpos);
 			if (othersub->validcount != ::validcount) CollectWithinRadius(PosRelative(othersub->sector), othersub, radius);
 		}
 	}
-	if (!subSec->sector->PortalBlocksSight(sector_t::floor))
+	if (!sec->PortalBlocksSight(sector_t::floor))
 	{
 		line_t *other = subSec->firstline->linedef;
-		AActor *sb = subSec->sector->SkyBoxes[sector_t::floor];
-		if (sb->specialf1 > Z() - radius)
+		if (sec->GetPortalPlaneZ(sector_t::floor) > Z() - radius)
 		{
-			DVector2 refpos = other->v1->fPos() + other->Delta() / 2 + sb->Scale;
+			DVector2 refpos = other->v1->fPos() + other->Delta() / 2 + sec->GetPortalDisplacement(sector_t::floor);
 			subsector_t *othersub = R_PointInSubsector(refpos);
 			if (othersub->validcount != ::validcount) CollectWithinRadius(PosRelative(othersub->sector), othersub, radius);
 		}
diff --git a/src/gl/scene/gl_bsp.cpp b/src/gl/scene/gl_bsp.cpp
index ca7eaf849..4377f68f1 100644
--- a/src/gl/scene/gl_bsp.cpp
+++ b/src/gl/scene/gl_bsp.cpp
@@ -494,7 +494,7 @@ static void DoSubsector(subsector_t * sub)
 
 	if (gl_render_flats)
 	{
-		// Subsectors with only 2 lines cannot have any area!
+		// Subsectors with only 2 lines cannot have any area
 		if (sub->numlines>2 || (sub->hacked&1)) 
 		{
 			// Exclude the case when it tries to render a sector with a heightsec
@@ -527,17 +527,17 @@ static void DoSubsector(subsector_t * sub)
 
 				FPortal *portal;
 
-				portal = fakesector->portals[sector_t::ceiling];
+				portal = fakesector->GetGLPortal(sector_t::ceiling);
 				if (portal != NULL)
 				{
-					GLSectorStackPortal *glportal = portal->GetGLPortal();
+					GLSectorStackPortal *glportal = portal->GetRenderState();
 					glportal->AddSubsector(sub);
 				}
 
-				portal = fakesector->portals[sector_t::floor];
+				portal = fakesector->GetGLPortal(sector_t::floor);
 				if (portal != NULL)
 				{
-					GLSectorStackPortal *glportal = portal->GetGLPortal();
+					GLSectorStackPortal *glportal = portal->GetRenderState();
 					glportal->AddSubsector(sub);
 				}
 			}
diff --git a/src/gl/scene/gl_fakeflat.cpp b/src/gl/scene/gl_fakeflat.cpp
index 29f2f52a3..70ac86ec7 100644
--- a/src/gl/scene/gl_fakeflat.cpp
+++ b/src/gl/scene/gl_fakeflat.cpp
@@ -212,8 +212,8 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 				dest->ceilingplane=sec->floorplane;
 				dest->ceilingplane.FlipVert();
 				dest->planes[sector_t::ceiling].TexZ = dest->planes[sector_t::floor].TexZ;
-				dest->portals[sector_t::ceiling] = NULL;
-				dest->portals[sector_t::floor] = NULL;
+				dest->ClearPortal(sector_t::ceiling);
+				dest->ClearPortal(sector_t::floor);
 				return dest;
 			}
 		}
@@ -314,7 +314,7 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 		dest->vboindex[sector_t::ceiling] = sec->vboindex[sector_t::vbo_fakefloor];
 		dest->vboheight[sector_t::ceiling] = s->vboheight[sector_t::floor];
 
-		dest->portals[sector_t::ceiling] = NULL;
+		dest->ClearPortal(sector_t::ceiling);
 
 		if (!(s->MoreFlags & SECF_NOFAKELIGHT))
 		{
@@ -367,7 +367,7 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 		dest->vboindex[sector_t::ceiling] = sec->vboindex[sector_t::ceiling];
 		dest->vboheight[sector_t::ceiling] = sec->vboheight[sector_t::ceiling];
 
-		dest->portals[sector_t::floor] = NULL;
+		dest->ClearPortal(sector_t::floor);
 
 		if (!(s->MoreFlags & SECF_NOFAKELIGHT))
 		{
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index 50b7fc9bb..3c2c661be 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -1180,20 +1180,21 @@ void GLHorizonPortal::DrawContents()
 void GLEEHorizonPortal::DrawContents()
 {
 	PortalAll.Clock();
-	if (origin->Sector->GetTexture(sector_t::floor) == skyflatnum ||
-		origin->Sector->GetTexture(sector_t::ceiling) == skyflatnum)
+	sector_t *sector = origin->Sector;
+	if (sector->GetTexture(sector_t::floor) == skyflatnum ||
+		sector->GetTexture(sector_t::ceiling) == skyflatnum)
 	{
 		GLSkyInfo skyinfo;
-		skyinfo.init(origin->Sector->sky, 0);
+		skyinfo.init(sector->sky, 0);
 		GLSkyPortal sky(&skyinfo, true);
 		sky.DrawContents();
 	}
-	if (origin->Sector->GetTexture(sector_t::ceiling) != skyflatnum)
+	if (sector->GetTexture(sector_t::ceiling) != skyflatnum)
 	{
 		GLHorizonInfo horz;
-		horz.plane.GetFromSector(origin->Sector, true);
-		horz.lightlevel = gl_ClampLight(origin->Sector->GetCeilingLight());
-		horz.colormap = origin->Sector->ColorMap;
+		horz.plane.GetFromSector(sector, true);
+		horz.lightlevel = gl_ClampLight(sector->GetCeilingLight());
+		horz.colormap = sector->ColorMap;
 		if (origin->special1 == SKYBOX_PLANE)
 		{
 			horz.plane.Texheight = ViewPos.Z + fabs(horz.plane.Texheight);
@@ -1201,12 +1202,12 @@ void GLEEHorizonPortal::DrawContents()
 		GLHorizonPortal ceil(&horz, true);
 		ceil.DrawContents();
 	}
-	if (origin->Sector->GetTexture(sector_t::floor) != skyflatnum)
+	if (sector->GetTexture(sector_t::floor) != skyflatnum)
 	{
 		GLHorizonInfo horz;
-		horz.plane.GetFromSector(origin->Sector, false);
-		horz.lightlevel = gl_ClampLight(origin->Sector->GetFloorLight());
-		horz.colormap = origin->Sector->ColorMap;
+		horz.plane.GetFromSector(sector, false);
+		horz.lightlevel = gl_ClampLight(sector->GetFloorLight());
+		horz.colormap = sector->ColorMap;
 		if (origin->special1 == SKYBOX_PLANE)
 		{
 			horz.plane.Texheight = ViewPos.Z - fabs(horz.plane.Texheight);
diff --git a/src/gl/scene/gl_renderhacks.cpp b/src/gl/scene/gl_renderhacks.cpp
index 80f64d02e..30de38eb7 100644
--- a/src/gl/scene/gl_renderhacks.cpp
+++ b/src/gl/scene/gl_renderhacks.cpp
@@ -669,7 +669,6 @@ void FDrawInfo::DrawUnhandledMissingTextures()
 		if (seg->linedef->validcount == validcount) continue;		// already done
 		seg->linedef->validcount = validcount;
 		if (seg->frontsector->GetPlaneTexZF(sector_t::ceiling) < ViewPos.Z) continue;	// out of sight
-		//if (seg->frontsector->ceilingpic==skyflatnum) continue;
 
 		// FIXME: The check for degenerate subsectors should be more precise
 		if (seg->PartnerSeg && (seg->PartnerSeg->Subsector->flags & SSECF_DEGENERATE)) continue;
@@ -688,7 +687,6 @@ void FDrawInfo::DrawUnhandledMissingTextures()
 
 		seg_t * seg = MissingLowerSegs[i].seg;
 
-		// already done!
 		if (seg->linedef->validcount == validcount) continue;		// already done
 		seg->linedef->validcount = validcount;
 		if (!(sectorrenderflags[seg->backsector->sectornum] & SSRF_RENDERFLOOR)) continue;
@@ -1049,7 +1047,7 @@ void FDrawInfo::CollectSectorStacksCeiling(subsector_t * sub, sector_t * anchor)
 	sub->validcount=validcount;
 
 	// Has a sector stack or skybox itself!
-	if (sub->render_sector->portals[sector_t::ceiling] != NULL) return;
+	if (sub->render_sector->GetGLPortal(sector_t::ceiling) != nullptr) return;
 
 	// Don't bother processing unrendered subsectors
 	if (sub->numlines>2 && !(ss_renderflags[DWORD(sub-subsectors)]&SSRF_PROCESSED)) return;
@@ -1096,7 +1094,7 @@ void FDrawInfo::CollectSectorStacksFloor(subsector_t * sub, sector_t * anchor)
 	sub->validcount=validcount;
 
 	// Has a sector stack or skybox itself!
-	if (sub->render_sector->portals[sector_t::floor] != NULL) return;
+	if (sub->render_sector->GetGLPortal(sector_t::floor) != nullptr) return;
 
 	// Don't bother processing unrendered subsectors
 	if (sub->numlines>2 && !(ss_renderflags[DWORD(sub-subsectors)]&SSRF_PROCESSED)) return;
@@ -1146,7 +1144,7 @@ void FDrawInfo::ProcessSectorStacks()
 	for (i=0;i<CeilingStacks.Size (); i++)
 	{
 		sector_t *sec = gl_FakeFlat(CeilingStacks[i], &fake, false);
-		FPortal *portal = sec->portals[sector_t::ceiling];
+		FPortal *portal = sec->GetGLPortal(sector_t::ceiling);
 		if (portal != NULL) for(int k=0;k<sec->subsectorcount;k++)
 		{
 			subsector_t * sub = sec->subsectors[k];
@@ -1170,10 +1168,10 @@ void FDrawInfo::ProcessSectorStacks()
 
 					if (sub->portalcoverage[sector_t::ceiling].subsectors == NULL)
 					{
-						gl_BuildPortalCoverage(&sub->portalcoverage[sector_t::ceiling],	sub, portal);
+						gl_BuildPortalCoverage(&sub->portalcoverage[sector_t::ceiling],	sub, portal->mDisplacement);
 					}
 
-					portal->GetGLPortal()->AddSubsector(sub);
+					portal->GetRenderState()->AddSubsector(sub);
 
 					if (sec->GetAlpha(sector_t::ceiling) != 0 && sec->GetTexture(sector_t::ceiling) != skyflatnum)
 					{
@@ -1190,7 +1188,7 @@ void FDrawInfo::ProcessSectorStacks()
 	for (i=0;i<FloorStacks.Size (); i++)
 	{
 		sector_t *sec = gl_FakeFlat(FloorStacks[i], &fake, false);
-		FPortal *portal = sec->portals[sector_t::floor];
+		FPortal *portal = sec->GetGLPortal(sector_t::floor);
 		if (portal != NULL) for(int k=0;k<sec->subsectorcount;k++)
 		{
 			subsector_t * sub = sec->subsectors[k];
@@ -1215,10 +1213,10 @@ void FDrawInfo::ProcessSectorStacks()
 
 					if (sub->portalcoverage[sector_t::floor].subsectors == NULL)
 					{
-						gl_BuildPortalCoverage(&sub->portalcoverage[sector_t::floor], sub, portal);
+						gl_BuildPortalCoverage(&sub->portalcoverage[sector_t::floor], sub, portal->mDisplacement);
 					}
 
-					GLSectorStackPortal *glportal = portal->GetGLPortal();
+					GLSectorStackPortal *glportal = portal->GetRenderState();
 					glportal->AddSubsector(sub);
 
 					if (sec->GetAlpha(sector_t::floor) != 0 && sec->GetTexture(sector_t::floor) != skyflatnum)
diff --git a/src/gl/scene/gl_sky.cpp b/src/gl/scene/gl_sky.cpp
index 6f6039c00..ab16f57ab 100644
--- a/src/gl/scene/gl_sky.cpp
+++ b/src/gl/scene/gl_sky.cpp
@@ -311,10 +311,14 @@ void GLWall::SkyTop(seg_t * seg,sector_t * fs,sector_t * bs,vertex_t * v1,vertex
 		}
 		else
 		{
-			FPortal *pfront = fs->portals[sector_t::ceiling];
-			FPortal *pback = bs->portals[sector_t::ceiling];
-			if (pfront == NULL || fs->PortalBlocksView(sector_t::ceiling)) return;
-			if (pfront == pback && !bs->PortalBlocksView(sector_t::ceiling)) return;
+			int type = fs->GetPortalType(sector_t::ceiling);
+			if (type == SKYBOX_STACKEDSECTORTHING || type == SKYBOX_PORTAL || type == SKYBOX_LINKEDPORTAL)
+			{
+				FPortal *pfront = fs->GetGLPortal(sector_t::ceiling);
+				FPortal *pback = bs->GetGLPortal(sector_t::ceiling);
+				if (pfront == NULL || fs->PortalBlocksView(sector_t::ceiling)) return;
+				if (pfront == pback && !bs->PortalBlocksView(sector_t::ceiling)) return;
+			}
 		}
 
 		// stacked sectors
@@ -386,10 +390,14 @@ void GLWall::SkyBottom(seg_t * seg,sector_t * fs,sector_t * bs,vertex_t * v1,ver
 		}
 		else
 		{
-			FPortal *pfront = fs->portals[sector_t::floor];
-			FPortal *pback = bs->portals[sector_t::floor];
-			if (pfront == NULL || fs->PortalBlocksView(sector_t::floor)) return;
-			if (pfront == pback && !bs->PortalBlocksView(sector_t::floor)) return;
+			int type = fs->GetPortalType(sector_t::floor);
+			if (type == SKYBOX_STACKEDSECTORTHING || type == SKYBOX_PORTAL || type == SKYBOX_LINKEDPORTAL)
+			{
+				FPortal *pfront = fs->GetGLPortal(sector_t::floor);
+				FPortal *pback = bs->GetGLPortal(sector_t::floor);
+				if (pfront == NULL || fs->PortalBlocksView(sector_t::floor)) return;
+				if (pfront == pback && !bs->PortalBlocksView(sector_t::floor)) return;
+			}
 		}
 
 		// stacked sectors
diff --git a/src/gl/scene/gl_sprite.cpp b/src/gl/scene/gl_sprite.cpp
index 4b797f71f..48c20fad4 100644
--- a/src/gl/scene/gl_sprite.cpp
+++ b/src/gl/scene/gl_sprite.cpp
@@ -554,8 +554,8 @@ void GLSprite::Process(AActor* thing, sector_t * sector, bool thruportal)
 	{
 		rendersector = sector;
 	}
-	topclip = rendersector->PortalBlocksMovement(sector_t::ceiling) ? LARGE_VALUE : rendersector->SkyBoxes[sector_t::ceiling]->specialf1;
-	bottomclip = rendersector->PortalBlocksMovement(sector_t::floor) ? -LARGE_VALUE : rendersector->SkyBoxes[sector_t::floor]->specialf1;
+	topclip = rendersector->PortalBlocksMovement(sector_t::ceiling) ? LARGE_VALUE : rendersector->GetPortalPlaneZ(sector_t::ceiling);
+	bottomclip = rendersector->PortalBlocksMovement(sector_t::floor) ? -LARGE_VALUE : rendersector->GetPortalPlaneZ(sector_t::floor);
 
 
 	x = thingpos.X;
diff --git a/src/gl/scene/gl_walls.cpp b/src/gl/scene/gl_walls.cpp
index 8f91b59cd..b9dfc9ef4 100644
--- a/src/gl/scene/gl_walls.cpp
+++ b/src/gl/scene/gl_walls.cpp
@@ -185,7 +185,7 @@ void GLWall::PutPortal(int ptype)
 		break;
 
 	case PORTALTYPE_SECTORSTACK:
-		portal = this->portal->GetGLPortal();
+		portal = this->portal->GetRenderState();
 		portal->AddLine(this);
 		break;
 
diff --git a/src/r_defs.h b/src/r_defs.h
index 6a3894f0e..1f2f35621 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -38,6 +38,7 @@
 #include "actor.h"
 struct FLightNode;
 struct FGLSection;
+struct FPortal;
 struct seg_t;
 
 #include "dthinker.h"
@@ -499,7 +500,6 @@ struct subsector_t;
 struct sector_t;
 struct side_t;
 extern bool gl_plane_reflection_i;
-struct FPortal;
 
 // Ceiling/floor flags
 enum
@@ -1159,6 +1159,8 @@ public:
 
 	float GetReflect(int pos) { return gl_plane_reflection_i? reflect[pos] : 0; }
 	bool VBOHeightcheck(int pos) const { return vboheight[pos] == GetPlaneTexZ(pos); }
+	FPortal *GetGLPortal(int plane) { return portals[plane]; }
+	void ClearPortal(int plane) { portals[plane] = nullptr;	SkyBoxes[plane] = nullptr; }
 
 	enum
 	{