diff --git a/src/gl/data/gl_setup.cpp b/src/gl/data/gl_setup.cpp
index a76e618d9a..cf2f62d74a 100644
--- a/src/gl/data/gl_setup.cpp
+++ b/src/gl/data/gl_setup.cpp
@@ -625,12 +625,38 @@ void gl_PreprocessLevel()
 	PrepareSegs();
 	PrepareSectorData();
 	InitVertexData();
+	int *checkmap = new int[numvertexes];
+	memset(checkmap, -1, sizeof(int)*numvertexes);
 	for(i=0;i<numsectors;i++) 
 	{
-		sectors[i].dirty = true;
 		sectors[i].sectornum = i;
 		PrepareTransparentDoors(&sectors[i]);
+
+		// This ignores vertices only used for seg splitting because those aren't needed here
+		for(int j = 0; j < sectors[i].linecount; j++)
+		{
+			line_t *l = sectors[i].lines[j];
+			if (l->sidedef[0]->Flags & WALLF_POLYOBJ) continue;	// don't bother with polyobjects
+
+			int vtnum1 = int(l->v1 - vertexes);
+			int vtnum2 = int(l->v2 - vertexes);
+
+			if (checkmap[numsectors + vtnum1] < i)
+			{
+				checkmap[numsectors + vtnum1] = i;
+				sectors[i].e->vertices.Push(&vertexes[vtnum1]);
+				vertexes[vtnum1].dirty = true;
+			}
+
+			if (checkmap[numsectors + vtnum2] < i)
+			{
+				checkmap[numsectors + vtnum2] = i;
+				sectors[i].e->vertices.Push(&vertexes[vtnum2]);
+				vertexes[vtnum2].dirty = true;
+			}
+		}
 	}
+	delete[] checkmap;
 
 	gl_InitPortals();
 
diff --git a/src/gl/system/gl_menu.cpp b/src/gl/system/gl_menu.cpp
index 75436209c6..2ec515300d 100644
--- a/src/gl/system/gl_menu.cpp
+++ b/src/gl/system/gl_menu.cpp
@@ -18,7 +18,6 @@ CVAR(Bool, gl_portals, true, 0)
 CVAR(Bool, gl_noquery, false, 0)
 CVAR(Bool,gl_mirrors,true,0)	// This is for debugging only!
 CVAR(Bool,gl_mirror_envmap, true, CVAR_GLOBALCONFIG|CVAR_ARCHIVE)
-CVAR(Bool, gl_render_segs, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 CVAR(Bool, gl_seamless, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 
 CUSTOM_CVAR(Int, r_mirror_recursions,4,CVAR_GLOBALCONFIG|CVAR_ARCHIVE)
@@ -34,7 +33,6 @@ CUSTOM_CVAR(Bool, gl_plane_reflection, true, CVAR_GLOBALCONFIG|CVAR_ARCHIVE)
 
 CUSTOM_CVAR(Bool, gl_render_precise, false, CVAR_ARCHIVE|CVAR_GLOBALCONFIG)
 {
-	//gl_render_segs=self;
 	gl_seamless=self;
 }
 
diff --git a/src/r_defs.h b/src/r_defs.h
index a87d46cc29..2a76510f83 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -438,6 +438,8 @@ struct extsector_t
 		TArray<lightlist_t>				lightlist;		// 3D light list
 		TArray<sector_t*>				attached;		// 3D floors attached to this sector
 	} XFloor;
+
+	TArray<vertex_t *> vertices;
 	
 	void Serialize(FArchive &arc);
 };
@@ -635,14 +637,28 @@ struct sector_t
 		return planes[pos].TexZ;
 	}
 
+	void SetVerticesDirty()
+	{
+		for (unsigned i = 0; i < e->vertices.Size(); i++) e->vertices[i]->dirty = true;
+	}
+
+	void SetAllVerticesDirty()
+	{
+		SetVerticesDirty();
+		for (unsigned i = 0; i < e->FakeFloor.Sectors.Size(); i++) e->FakeFloor.Sectors[i]->SetVerticesDirty();
+		for (unsigned i = 0; i < e->XFloor.attached.Size(); i++) e->XFloor.attached[i]->SetVerticesDirty();
+	}
+
 	void SetPlaneTexZ(int pos, fixed_t val)
 	{
 		planes[pos].TexZ = val;
+		SetAllVerticesDirty();
 	}
 
 	void ChangePlaneTexZ(int pos, fixed_t val)
 	{
 		planes[pos].TexZ += val;
+		SetAllVerticesDirty();
 	}
 
 	static inline short ClampLight(int level)
@@ -765,8 +781,6 @@ struct sector_t
 	// GL only stuff starts here
 	float						reflect[2];
 
-	int							dirtyframe[3];		// last frame this sector was marked dirty
-	bool						dirty;				// marked for recalculation
 	bool						transdoor;			// For transparent door hacks
 	fixed_t						transdoorheight;	// for transparent door hacks
 	int							subsectorcount;		// list of subsectors