diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index ca6d0f3c..665952a4 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,8 @@
 September 15, 2009  (Changes by Graf Zahl)
+- added thing activation types for BUMPSPECIAL and USESPECIAL. Also added
+  a new ClearSpecial flag to the activation type.
+- added MBF's code for dogs jumping down, controlled by the MF6_JUMPDOWN
+  flag.
 - fixed: The Dehacked flags parser fix from May 31 (r1624) was undone by
   yesterday's additions. Changed it so that the parser first checks for 
   the presence of a '-' sign before deciding whether to use strtol or
diff --git a/src/gl/common/glc_fakeflat.cpp b/src/gl/common/glc_fakeflat.cpp
index 2472b014..18d66879 100644
--- a/src/gl/common/glc_fakeflat.cpp
+++ b/src/gl/common/glc_fakeflat.cpp
@@ -327,6 +327,8 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 		{
 			dest->SetTexture(sector_t::floor, s->GetTexture(sector_t::floor), false);
 			dest->SetPlaneTexZ(sector_t::floor, s->GetPlaneTexZ(sector_t::floor));
+			dest->vboindex[sector_t::floor] = sec->vboindex[sector_t::vbo_fakefloor];
+			dest->vboheight[sector_t::floor] = s->vboheight[sector_t::floor];
 		}
 		else if (s->MoreFlags & SECF_FAKEFLOORONLY)
 		{
@@ -350,6 +352,9 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 	{
 		dest->SetPlaneTexZ(sector_t::floor, s->GetPlaneTexZ(sector_t::floor));
 		dest->floorplane   = s->floorplane;
+
+		dest->vboindex[sector_t::floor] = sec->vboindex[sector_t::vbo_fakefloor];
+		dest->vboheight[sector_t::floor] = s->vboheight[sector_t::floor];
 	}
 
 	if (!(s->MoreFlags&SECF_FAKEFLOORONLY))
@@ -360,12 +365,16 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 			{
 				dest->SetTexture(sector_t::ceiling, s->GetTexture(sector_t::ceiling), false);
 				dest->SetPlaneTexZ(sector_t::ceiling, s->GetPlaneTexZ(sector_t::ceiling));
+				dest->vboindex[sector_t::ceiling] = sec->vboindex[sector_t::vbo_fakeceiling];
+				dest->vboheight[sector_t::ceiling] = s->vboheight[sector_t::ceiling];
 			}
 		}
 		else
 		{
 			dest->ceilingplane  = s->ceilingplane;
 			dest->SetPlaneTexZ(sector_t::ceiling, s->GetPlaneTexZ(sector_t::ceiling));
+			dest->vboindex[sector_t::ceiling] = sec->vboindex[sector_t::vbo_fakeceiling];
+			dest->vboheight[sector_t::ceiling] = s->vboheight[sector_t::ceiling];
 		}
 	}
 
@@ -378,6 +387,12 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 		dest->ceilingplane=s->floorplane;
 		dest->ceilingplane.FlipVert();
 
+		dest->vboindex[sector_t::floor] = sec->vboindex[sector_t::floor];
+		dest->vboheight[sector_t::floor] = sec->vboheight[sector_t::floor];
+
+		dest->vboindex[sector_t::ceiling] = sec->vboindex[sector_t::vbo_fakefloor];
+		dest->vboheight[sector_t::ceiling] = s->vboheight[sector_t::floor];
+
 		if (!back)
 		{
 			dest->SetTexture(sector_t::floor, diffTex ? sec->GetTexture(sector_t::floor) : s->GetTexture(sector_t::floor), false);
@@ -419,6 +434,12 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 		dest->floorplane = s->ceilingplane;
 		dest->floorplane.FlipVert();
 
+		dest->vboindex[sector_t::floor] = sec->vboindex[sector_t::vbo_fakeceiling];
+		dest->vboheight[sector_t::floor] = s->vboheight[sector_t::ceiling];
+
+		dest->vboindex[sector_t::ceiling] = sec->vboindex[sector_t::ceiling];
+		dest->vboheight[sector_t::ceiling] = sec->vboheight[sector_t::ceiling];
+
 		if (!back)
 		{
 			dest->SetTexture(sector_t::ceiling, diffTex ? sec->GetTexture(sector_t::ceiling) : s->GetTexture(sector_t::ceiling), false);
@@ -427,7 +448,6 @@ sector_t * gl_FakeFlat(sector_t * sec, sector_t * dest, area_t in_area, bool bac
 			
 			if (s->GetTexture(sector_t::floor) != skyflatnum)
 			{
-				dest->ceilingplane	= sec->ceilingplane;
 				dest->SetTexture(sector_t::floor, s->GetTexture(sector_t::floor), false);
 				dest->planes[sector_t::floor].xform = s->planes[sector_t::floor].xform;
 			}
diff --git a/src/gl/common/glc_setup.cpp b/src/gl/common/glc_setup.cpp
index f03e42de..30ea05a9 100644
--- a/src/gl/common/glc_setup.cpp
+++ b/src/gl/common/glc_setup.cpp
@@ -689,48 +689,133 @@ static void PrepareSegs()
 
 //==========================================================================
 //
-// creates a VBO for flat geometry - just a rough test for now.
+// creates a VBO for flat geometry 
+// Vertices are ordered by sector plane (i.e. all attached sectors are
+// calculated along with the master so that changing the height of a 
+// plane doesn't result in multiple ranges of the VBO to become invalid)
 //
 //==========================================================================
 unsigned int gl_vbo;
 
 TArray<FVBOVertex> vbo_data;
 
+static void SetVertex(int idx, vertex_t *vt, secplane_t & plane)
+{
+	vbo_data[idx].x = vt->fx;
+	vbo_data[idx].y = vt->fy;
+	vbo_data[idx].z = plane.ZatPoint(vt->fx, vt->fy);
+	vbo_data[idx].u = vt->fx/64.f;
+	vbo_data[idx].v = -vt->fy/64.f;
+}
+
+static F3DFloor *Find3DFloor(sector_t *target, sector_t *model)
+{
+	for(unsigned i=0; i<target->e->XFloor.ffloors.Size(); i++)
+	{
+		F3DFloor *ffloor = target->e->XFloor.ffloors[i];
+		if (ffloor->model == model) return ffloor;
+	}
+	return NULL;
+}
+
+
 static void CreateFlatVBO()
 {
 
-	for (int h=0;h<2;h++)
+	for (int h = sector_t::floor; h <= sector_t::ceiling; h++)
 	{
 		for(int i=0; i<numsectors;i++)
 		{
 			sector_t *sec = &sectors[i];
 
-			sec->vboheight[h] = sec->GetPlaneTexZ(h? sector_t::floor:sector_t::ceiling);
+			sec->vboindex[h] = vbo_data.Size();
+			sec->vboheight[h] = sec->GetPlaneTexZ(h);
 
+			// First calculate the vertices for the sector itself
 			for(int j=0; j<sec->subsectorcount; j++)
 			{
 				subsector_t *sub = sec->subsectors[j];
 
-				sub->vboindex[h] = vbo_data.Size();
-
-				int idx = vbo_data.Reserve(sub->numvertices);
-				for(int k=0; k<sub->numvertices; k++, idx++)
+				int idx = vbo_data.Reserve(sub->numlines);
+				for(int k=0; k<sub->numlines; k++, idx++)
 				{
-					seg_t *seg = &segs[sub->firstline+k];
-					vertex_t *vt = seg->v1;
-
-					vbo_data[idx].x = vt->fx;
-					vbo_data[idx].y = vt->fy;
-					vbo_data[idx].u = vt->fx/64.f;
-					vbo_data[idx].v = -vt->fy/64.f;
-					vbo_data[idx].z = float( h==0? 
-						sec->ceilingplane.ZatPoint(vt->fx, vt->fy) :
-						sec->floorplane.ZatPoint(vt->fx, vt->fy));
-
+					SetVertex(idx, segs[sub->firstline+k].v1, sec->GetSecPlane(h));
+					if (sec->transdoor && h == sector_t::floor) vbo_data[idx].z -= 1.f;
 				}
 			}
+
+			// Next are all sectors using this one as heightsec
+			TArray<sector_t *> &fakes = sec->e->FakeFloor.Sectors;
+			for (unsigned g=0; g<fakes.Size(); g++)
+			{
+				sector_t *fsec = fakes[g];
+				fsec->vboindex[2+h] = vbo_data.Size();	// set the index info in the attached sector
+
+				for(int j=0; j<fsec->subsectorcount; j++)
+				{
+					subsector_t *sub = fsec->subsectors[j];
+
+					int idx = vbo_data.Reserve(sub->numlines);
+					for(int k=0; k<sub->numlines; k++, idx++)
+					{
+						SetVertex(idx, segs[sub->firstline+k].v1, sec->GetSecPlane(h));
+					}
+				}
+			}
+
+			// and finally all attached 3D floors
+			TArray<sector_t *> &xf = sec->e->XFloor.attached;
+			for (unsigned g=0; g<xf.Size(); g++)
+			{
+				sector_t *fsec = xf[g];
+				F3DFloor *ffloor = Find3DFloor(fsec, sec);
+
+				if (ffloor != NULL && ffloor->flags & FF_RENDERPLANES)
+				{
+					bool dotop = (ffloor->top.model == sec) && (ffloor->top.isceiling == h);
+					bool dobottom = (ffloor->bottom.model == sec) && (ffloor->bottom.isceiling == h);
+
+					if (dotop || dobottom)
+					{
+						if (dotop) ffloor->top.vindex = vbo_data.Size();
+						if (dobottom) ffloor->bottom.vindex = vbo_data.Size();
+					
+						for(int j=0; j<fsec->subsectorcount; j++)
+						{
+							subsector_t *sub = fsec->subsectors[j];
+
+							int idx = vbo_data.Reserve(sub->numlines);
+							for(int k=0; k<sub->numlines; k++, idx++)
+							{
+								SetVertex(idx, segs[sub->firstline+k].v1, sec->GetSecPlane(h));
+							}
+						}
+					}
+				}
+			}
+			sec->vbocount[h] = vbo_data.Size() - sec->vboindex[h];
+		}
+	}
+
+	// We need to do a final check for Vavoom water and FF_FIX sectors.
+	// No new vertices are needed here. The planes come from the actual sector
+	for(int i=0; i<numsectors;i++)
+	{
+		for(unsigned j=0;j<sectors[i].e->XFloor.ffloors.Size(); j++)
+		{
+			F3DFloor *ff = sectors[i].e->XFloor.ffloors[j];
+
+			if (ff->top.model == &sectors[i])
+			{
+				ff->top.vindex = sectors[i].vboindex[ff->top.isceiling];
+			}
+			if (ff->bottom.model == &sectors[i])
+			{
+				ff->bottom.vindex = sectors[i].vboindex[ff->top.isceiling];
+			}
 		}
 	}
+
 	if (gl_vbo <= 0) gl.GenBuffers(1, &gl_vbo);
 	gl.BindBuffer(GL_ARRAY_BUFFER, gl_vbo);
 	gl.BufferData(GL_ARRAY_BUFFER, vbo_data.Size() * sizeof(FVBOVertex), &vbo_data[0], GL_DYNAMIC_DRAW);
diff --git a/src/gl/common/glc_structs.h b/src/gl/common/glc_structs.h
index aa28aba6..7a3bef2e 100644
--- a/src/gl/common/glc_structs.h
+++ b/src/gl/common/glc_structs.h
@@ -17,25 +17,16 @@ struct GLSectorPlane
 	fixed_t	xscale, yscale;
 	angle_t	angle;
 
-	void GetFromSector(sector_t * sec, bool ceiling)
+	void GetFromSector(sector_t * sec, int ceiling)
 	{
 		xoffs = sec->GetXOffset(ceiling);
 		yoffs = sec->GetYOffset(ceiling);
 		xscale = sec->GetXScale(ceiling);
 		yscale = sec->GetYScale(ceiling);
 		angle = sec->GetAngle(ceiling);
-		if (ceiling)
-		{
-			texture = sec->GetTexture(sector_t::ceiling);
-			plane = sec->ceilingplane;
-			texheight = plane.d;
-		}
-		else
-		{
-			texture = sec->GetTexture(sector_t::floor);
-			plane = sec->floorplane;
-			texheight = -plane.d;
-		}
+		texture = sec->GetTexture(ceiling);
+		plane = sec->GetSecPlane(ceiling);
+		texheight = (ceiling = sector_t::ceiling)? plane.d : -plane.d;
 	}
 };
 
diff --git a/src/gl/old_renderer/gl1_flats.cpp b/src/gl/old_renderer/gl1_flats.cpp
index 41cb95fe..0c50d598 100644
--- a/src/gl/old_renderer/gl1_flats.cpp
+++ b/src/gl/old_renderer/gl1_flats.cpp
@@ -102,9 +102,9 @@ void gl_SetPlaneTextureRotation(const GLSectorPlane * secplane, FGLTexture * glt
 void GLFlat::DrawSubsectorLights(subsector_t * sub, int pass)
 {
 	Plane p;
-	Vector nearPt, up, right;
+	Vector nearPt, up, right, t1;
 	float scale;
-	int k;
+	int k, v;
 
 	FLightNode * node = sub->lighthead[pass==GLPASS_LIGHT_ADDITIVE];
 	gl_DisableShader();
@@ -137,17 +137,18 @@ void GLFlat::DrawSubsectorLights(subsector_t * sub, int pass)
 
 		// Render the light
 		gl.Begin(GL_TRIANGLE_FAN);
-		for(k = 0; k < sub->numvertices; k++)
+		for(k = 0, v = sub->firstline; k < sub->numlines; k++, v++)
 		{
-			Vector t1;
-			GLVertex * vt = &gl_vertices[sub->firstvertex + k];
+			vertex_t *vt = segs[v].v1;
+			float zc = plane.plane.ZatPoint(vt->fx, vt->fy) + z;
 
-			float z = plane.plane.ZatPoint(vt->x, vt->y);
-			t1.Set(vt->x, z, vt->y);
+			t1.Set(vt->fx, zc, vt->fy);
 			Vector nearToVert = t1 - nearPt;
 			gl.TexCoord2f( (nearToVert.Dot(right) * scale) + 0.5f, (nearToVert.Dot(up) * scale) + 0.5f);
-			gl.Vertex3f(vt->x, z, vt->y);
+
+			gl.Vertex3f(vt->fx, zc, vt->fy);
 		}
+
 		gl.End();
 		node = node->nextLight;
 	}
@@ -161,19 +162,18 @@ void GLFlat::DrawSubsectorLights(subsector_t * sub, int pass)
 
 void GLFlat::DrawSubsector(subsector_t * sub)
 {
-	int k;
-	int v;
-
 	gl.Begin(GL_TRIANGLE_FAN);
-	for(k = 0, v = sub->firstvertex; k < sub->numvertices; k++, v++)
+
+	for(int k=0; k<sub->numlines; k++)
 	{
-		gl.TexCoord2f(gl_vertices[v].u, gl_vertices[v].v);
-		float z = plane.plane.ZatPoint(gl_vertices[v].x, gl_vertices[v].y);
-		gl.Vertex3f(gl_vertices[v].x, z, gl_vertices[v].y);
+		vertex_t *vt = segs[sub->firstline+k].v1;
+		gl.TexCoord2f(vt->fx/64.f, -vt->fy/64.f);
+		float zc = plane.plane.ZatPoint(vt->fx, vt->fy);// + z;
+		gl.Vertex3f(vt->fx, zc, vt->fy);
 	}
 	gl.End();
 
-	flatvertices += sub->numvertices;
+	flatvertices += sub->numlines;
 	flatprimitives++;
 }
 
@@ -194,18 +194,21 @@ void GLFlat::DrawSubsectors(bool istrans)
 	}
 	else
 	{
-		if (gl_usevbo && (gl.flags&RFL_VBO) && !(renderflags&SSRF_RENDER3DPLANES) && 
-			sector->GetPlaneTexZ(this->ceiling? sector_t::ceiling:sector_t::floor) == sector->vboheight[!ceiling])
+		if (gl_usevbo && (gl.flags&RFL_VBO) && vboindex >= 0)
 		{
 			//gl.Color3f( 1.f,.5f,.5f);
+			int index = vboindex;
 			for (int i=0; i<sector->subsectorcount; i++)
 			{
 				subsector_t * sub = sector->subsectors[i];
 				// This is just a quick hack to make translucent 3D floors and portals work.
 				if (gl_drawinfo->ss_renderflags[sub-subsectors]&renderflags || istrans)
 				{
-					gl.DrawArrays(GL_TRIANGLE_FAN, sub->vboindex[!ceiling], sub->numlines);
+					gl.DrawArrays(GL_TRIANGLE_FAN, index, sub->numlines);
+					flatvertices += sub->numlines;
+					flatprimitives++;
 				}
+				index += sub->numlines;
 			}
 		}
 		else
@@ -411,7 +414,7 @@ inline void GLFlat::PutFlat(bool fog)
 //
 //==========================================================================
 
-void GLFlat::Process(sector_t * sector, bool whichplane, bool fog)
+void GLFlat::Process(sector_t * sector, int whichplane, bool fog)
 {
 	plane.GetFromSector(sector, whichplane);
 
@@ -434,14 +437,42 @@ void GLFlat::Process(sector_t * sector, bool whichplane, bool fog)
 	}
 
 	// get height from vplane
-	z=TO_GL(plane.texheight);
-
-	if (!whichplane && sector->transdoor) z -= 1;
+	if (whichplane == sector_t::floor && sector->transdoor) z = -1;
+	else z = 0;
 	
 	PutFlat(fog);
 	rendered_flats++;
 }
 
+//==========================================================================
+//
+// Sets 3D floor info. Common code for all 4 cases 
+//
+//==========================================================================
+
+void GLFlat::SetFrom3DFloor(F3DFloor *rover, bool top, bool underside)
+{
+	F3DFloor::planeref & plane = top? rover->top : rover->bottom;
+
+	// FF_FOG requires an inverted logic where to get the light from
+	lightlist_t *light = P_GetPlaneLight(sector, plane.plane, underside);
+	lightlevel = *light->p_lightlevel;
+	
+	if (rover->flags & FF_FOG) Colormap.LightColor = (*light->p_extra_colormap)->Fade;
+	else Colormap.CopyLightColor(*light->p_extra_colormap);
+
+	alpha = rover->alpha/255.0f;
+	renderstyle = rover->flags&FF_ADDITIVETRANS? STYLE_Add : STYLE_Translucent;
+	if (plane.model->VBOHeightcheck(plane.isceiling))
+	{
+		vboindex = plane.vindex;
+	}
+	else
+	{
+		vboindex = -1;
+	}
+}
+
 //==========================================================================
 //
 // Process a sector's flats for rendering
@@ -498,6 +529,14 @@ void GLFlat::ProcessSector(sector_t * frontsector, subsector_t * sub)
 			Colormap=frontsector->ColorMap;
 			stack = frontsector->FloorSkyBox && frontsector->FloorSkyBox->bAlways;
 			alpha= stack ? frontsector->FloorSkyBox->PlaneAlpha/65536.0f : 1.0f-frontsector->GetFloorReflect();
+			if (frontsector->VBOHeightcheck(sector_t::floor))
+			{
+				vboindex = frontsector->vboindex[sector_t::floor];
+			}
+			else
+			{
+				vboindex = -1;
+			}
 
 			ceiling=false;
 			renderflags=SSRF_RENDERFLOOR;
@@ -537,6 +576,14 @@ void GLFlat::ProcessSector(sector_t * frontsector, subsector_t * sub)
 			Colormap=frontsector->ColorMap;
 			stack = frontsector->CeilingSkyBox && frontsector->CeilingSkyBox->bAlways;
 			alpha=stack ? frontsector->CeilingSkyBox->PlaneAlpha/65536.0f : 1.0f-frontsector->GetCeilingReflect();
+			if (frontsector->VBOHeightcheck(sector_t::ceiling))
+			{
+				vboindex = frontsector->vboindex[sector_t::ceiling];
+			}
+			else
+			{
+				vboindex = -1;
+			}
 
 			ceiling=true;
 			renderflags=SSRF_RENDERCEILING;
@@ -596,17 +643,8 @@ void GLFlat::ProcessSector(sector_t * frontsector, subsector_t * sub)
 						{
 							if (TO_GL(viewz) <= rover->top.plane->ZatPoint(TO_GL(viewx), TO_GL(viewy)))
 							{
-								// FF_FOG requires an inverted logic where to get the light from
-								light=P_GetPlaneLight(sector, rover->top.plane,!!(rover->flags&FF_FOG));
-								lightlevel=*light->p_lightlevel;
-								
-								if (rover->flags&FF_FOG) Colormap.LightColor = (*light->p_extra_colormap)->Fade;
-								else Colormap.CopyLightColor(*light->p_extra_colormap);
-
+								SetFrom3DFloor(rover, true, !!(rover->flags&FF_FOG));
 								Colormap.FadeColor=frontsector->ColorMap->Fade;
-
-								alpha=rover->alpha/255.0f;
-								renderstyle = rover->flags&FF_ADDITIVETRANS? STYLE_Add : STYLE_Translucent;
 								Process(rover->top.model, rover->top.isceiling, !!(rover->flags&FF_FOG));
 							}
 							lastceilingheight=ff_top;
@@ -619,16 +657,8 @@ void GLFlat::ProcessSector(sector_t * frontsector, subsector_t * sub)
 						{
 							if (TO_GL(viewz)<=rover->bottom.plane->ZatPoint(TO_GL(viewx), TO_GL(viewy)))
 							{
-								light=P_GetPlaneLight(sector, rover->bottom.plane,!(rover->flags&FF_FOG));
-								lightlevel=*light->p_lightlevel;
-
-								if (rover->flags&FF_FOG) Colormap.LightColor = (*light->p_extra_colormap)->Fade;
-								else Colormap.CopyLightColor(*light->p_extra_colormap);
-
+								SetFrom3DFloor(rover, false, !(rover->flags&FF_FOG));
 								Colormap.FadeColor=frontsector->ColorMap->Fade;
-
-								alpha=rover->alpha/255.0f;
-								renderstyle = rover->flags&FF_ADDITIVETRANS? STYLE_Add : STYLE_Translucent;
 								Process(rover->bottom.model, rover->bottom.isceiling, !!(rover->flags&FF_FOG));
 							}
 							lastceilingheight=ff_bottom;
@@ -653,24 +683,15 @@ void GLFlat::ProcessSector(sector_t * frontsector, subsector_t * sub)
 						{
 							if (TO_GL(viewz) >= rover->bottom.plane->ZatPoint(TO_GL(viewx), TO_GL(viewy)))
 							{
+								SetFrom3DFloor(rover, false, !(rover->flags&FF_FOG));
+								Colormap.FadeColor=frontsector->ColorMap->Fade;
+
 								if (rover->flags&FF_FIX)
 								{
 									lightlevel = rover->model->lightlevel;
 									Colormap = rover->model->ColorMap;
 								}
-								else
-								{
-									light=P_GetPlaneLight(sector, rover->bottom.plane,!(rover->flags&FF_FOG));
-									lightlevel=*light->p_lightlevel;
 
-									if (rover->flags&FF_FOG) Colormap.LightColor = (*light->p_extra_colormap)->Fade;
-									else Colormap.CopyLightColor(*light->p_extra_colormap);
-
-									Colormap.FadeColor=frontsector->ColorMap->Fade;
-								}
-
-								alpha=rover->alpha/255.0f;
-								renderstyle = rover->flags&FF_ADDITIVETRANS? STYLE_Add : STYLE_Translucent;
 								Process(rover->bottom.model, rover->bottom.isceiling, !!(rover->flags&FF_FOG));
 							}
 							lastfloorheight=ff_bottom;
@@ -683,16 +704,8 @@ void GLFlat::ProcessSector(sector_t * frontsector, subsector_t * sub)
 						{
 							if (TO_GL(viewz) >= rover->top.plane->ZatPoint(TO_GL(viewx), TO_GL(viewy)))
 							{
-								light=P_GetPlaneLight(sector, rover->top.plane,!!(rover->flags&FF_FOG));
-								lightlevel=*light->p_lightlevel;
-
-								if (rover->flags&FF_FOG) Colormap.LightColor = (*light->p_extra_colormap)->Fade;
-								else Colormap.CopyLightColor(*light->p_extra_colormap);
-
+								SetFrom3DFloor(rover, true, !!(rover->flags&FF_FOG));
 								Colormap.FadeColor=frontsector->ColorMap->Fade;
-
-								alpha=rover->alpha/255.0f;
-								renderstyle = rover->flags&FF_ADDITIVETRANS? STYLE_Add : STYLE_Translucent;
 								Process(rover->top.model, rover->top.isceiling, !!(rover->flags&FF_FOG));
 							}
 							lastfloorheight=ff_top;
diff --git a/src/gl/old_renderer/gl1_renderer.cpp b/src/gl/old_renderer/gl1_renderer.cpp
index cce85fc9..3ee7c9da 100644
--- a/src/gl/old_renderer/gl1_renderer.cpp
+++ b/src/gl/old_renderer/gl1_renderer.cpp
@@ -232,39 +232,8 @@ unsigned char *GL1Renderer::GetTextureBuffer(FTexture *tex, int &w, int &h)
 //
 //===========================================================================
 
-TArray<GLVertex> gl_vertices(1024);
-
 void GL1Renderer::SetupLevel()
 {
-	int i,j;
-
-	gl_vertices.Resize(100);	
-	gl_vertices.Clear();	
-
-	// Create the flat vertex array
-	for (i=0; i<numsubsectors; i++)
-	{
-		subsector_t * ssector = &subsectors[i];
-
-		if (ssector->numlines<=2) continue;
-			
-		ssector->numvertices = ssector->numlines;
-		ssector->firstvertex = gl_vertices.Size();
-
-		for(j = 0;  j < (int)ssector->numlines; j++)
-		{
-			seg_t * seg = &segs[ssector->firstline + j];
-			vertex_t * vtx = seg->v1;
-			GLVertex * vt=&gl_vertices[gl_vertices.Reserve(1)];
-
-			vt->u = vtx->fx/64.0f;
-			vt->v = -vtx->fy/64.0f;
-			vt->x = vtx->fx;
-			vt->y = vtx->fy;
-			vt->z = 0.0f;
-			vt->vt = vtx;
-		}
-	}
 	mAngles.Pitch = 0.0f;
 }
 
diff --git a/src/gl/old_renderer/gl1_renderstruct.h b/src/gl/old_renderer/gl1_renderstruct.h
index 49bdfb4b..0f10268f 100644
--- a/src/gl/old_renderer/gl1_renderstruct.h
+++ b/src/gl/old_renderer/gl1_renderstruct.h
@@ -111,13 +111,16 @@ public:
 	bool foggy;
 	bool ceiling;
 	BYTE renderflags;
+	int vboindex;
+	int vboheight;
 
 	void DrawSubsector(subsector_t * sub);
 	void DrawSubsectorLights(subsector_t * sub, int pass);
 	void DrawSubsectors(bool istrans);
 
 	void PutFlat(bool fog = false);
-	void Process(sector_t * sector, bool whichplane, bool notexture);
+	void Process(sector_t * sector, int whichplane, bool notexture);
+	void SetFrom3DFloor(F3DFloor *rover, bool top, bool underside);
 	void ProcessSector(sector_t * frontsector, subsector_t * sub);
 	void Draw(int pass);
 };
diff --git a/src/p_3dfloors.cpp b/src/p_3dfloors.cpp
index fb641ccb..3d82d6d9 100644
--- a/src/p_3dfloors.cpp
+++ b/src/p_3dfloors.cpp
@@ -74,14 +74,14 @@ static void P_Add3DFloor(sector_t* sec, sector_t* sec2, line_t* master, int flag
 		ffloor->bottom.plane = &sec2->floorplane;
 		ffloor->bottom.texture = &sec2->planes[sector_t::floor].Texture;
 		ffloor->bottom.texheight = &sec2->planes[sector_t::floor].TexZ;
-		ffloor->bottom.isceiling = false;
+		ffloor->bottom.isceiling = sector_t::floor;
 	}
 	else 
 	{
 		ffloor->bottom.plane = &sec2->ceilingplane;
 		ffloor->bottom.texture = &sec2->planes[sector_t::ceiling].Texture;
 		ffloor->bottom.texheight = &sec2->planes[sector_t::ceiling].TexZ;
-		ffloor->bottom.isceiling = true;
+		ffloor->bottom.isceiling = sector_t::ceiling;
 	}
 	
 	if (!(flags&FF_FIX))
@@ -90,7 +90,7 @@ static void P_Add3DFloor(sector_t* sec, sector_t* sec2, line_t* master, int flag
 		ffloor->top.texture = &sec2->planes[sector_t::ceiling].Texture;
 		ffloor->top.texheight = &sec2->planes[sector_t::ceiling].TexZ;
 		ffloor->toplightlevel = &sec2->lightlevel;
-		ffloor->top.isceiling = true;
+		ffloor->top.isceiling = sector_t::ceiling;
 	}
 	else	// FF_FIX is a special case to patch rendering holes
 	{
@@ -98,7 +98,7 @@ static void P_Add3DFloor(sector_t* sec, sector_t* sec2, line_t* master, int flag
 		ffloor->top.texture = &sec2->planes[sector_t::floor].Texture;
 		ffloor->top.texheight = &sec2->planes[sector_t::floor].TexZ;
 		ffloor->toplightlevel = &sec->lightlevel;
-		ffloor->top.isceiling = false;
+		ffloor->top.isceiling = sector_t::floor;
 		ffloor->top.model = sec;
 	}
 
@@ -117,12 +117,14 @@ static void P_Add3DFloor(sector_t* sec, sector_t* sec2, line_t* master, int flag
 			// fortunately this plane won't be rendered - otherwise this wouldn't work...
 			ffloor->bottom.plane=&sec->floorplane;
 			ffloor->bottom.model=sec;
+			ffloor->bottom.isceiling = sector_t::floor;
 		}
 	}
 
 	ffloor->flags  = flags;
 	ffloor->master = master;
 	ffloor->alpha  = transluc;
+	ffloor->top.vindex = ffloor->bottom.vindex = -1;
 
 	// The engine cannot handle sloped translucent floors. Sorry
 	if (ffloor->top.plane->a || ffloor->top.plane->b || ffloor->bottom.plane->a || ffloor->bottom.plane->b)
diff --git a/src/p_3dfloors.h b/src/p_3dfloors.h
index c6838c09..f22d40a3 100644
--- a/src/p_3dfloors.h
+++ b/src/p_3dfloors.h
@@ -69,7 +69,8 @@ struct F3DFloor
 		const FTextureID *	texture;
 		const fixed_t *		texheight;
 		sector_t *		model;
-		bool			isceiling;
+		int				isceiling;
+		int				vindex;
 	};
 
 	planeref			bottom;
diff --git a/src/r_defs.h b/src/r_defs.h
index 2b5b271e..a8bea4cc 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -645,6 +645,11 @@ struct sector_t
 		return lightlevel;
 	}
 
+	secplane_t &GetSecPlane(int pos)
+	{
+		return pos == floor? floorplane:ceilingplane;
+	}
+
 
 	// Member variables
 	fixed_t		CenterFloor () const { return floorplane.ZatPoint (soundorg[0], soundorg[1]); }
@@ -746,10 +751,20 @@ struct sector_t
 	fixed_t						transdoorheight;	// for transparent door hacks
 	int							subsectorcount;		// list of subsectors
 	subsector_t **				subsectors;
-	fixed_t			vboheight[2];
+
+	enum
+	{
+		vbo_fakefloor = floor+2,
+		vbo_fakeceiling = ceiling+2,
+	};
+
+	int				vboindex[4];	// VBO indices of the 4 planes this sector uses during rendering
+	fixed_t			vboheight[2];	// Last calculated height for the 2 planes of this actual sector
+	int				vbocount[2];	// Total count of vertices belonging to this sector's planes
 
 	float GetFloorReflect() { return gl_plane_reflection_i? floor_reflect : 0; }
 	float GetCeilingReflect() { return gl_plane_reflection_i? ceiling_reflect : 0; }
+	bool VBOHeightcheck(int pos) const { return vboheight[pos] == GetPlaneTexZ(pos); }
 
 	enum
 	{
@@ -1009,14 +1024,11 @@ struct subsector_t
 	FGLSection *	section;		// section this subsector belongs to
 	FLightNode *	lighthead[2];	// Light nodes (blended and additive)
 	sector_t *		render_sector;	// The sector this belongs to for rendering
-	int				firstvertex;	// index into the gl_vertices array
-	int				numvertices;
 	int				validcount2;	// Second v
 	fixed_t			bbox[4];		// Bounding box
 	bool			degenerate;
 	char			hacked;			// 1: is part of a render hack
 									// 2: has one-sided walls
-	int				vboindex[2];
 };
 
 //