diff --git a/src/gl/scene/gl_flats.cpp b/src/gl/scene/gl_flats.cpp
index 378cd81f0..d8329f214 100644
--- a/src/gl/scene/gl_flats.cpp
+++ b/src/gl/scene/gl_flats.cpp
@@ -64,6 +64,9 @@
 #include "gl/utility/gl_convert.h"
 #include "gl/utility/gl_templates.h"
 
+#ifdef _DEBUG
+CVAR(Int, gl_breaksec, -1, 0)
+#endif
 //==========================================================================
 //
 // Sets the texture matrix according to the plane's texture positioning
@@ -328,7 +331,7 @@ void GLFlat::Draw(int pass, bool trans)	// trans only has meaning for GLPASS_LIG
 	int rel = getExtraLight();
 
 #ifdef _DEBUG
-	if (sector->sectornum == 130)
+	if (sector->sectornum == gl_breaksec)
 	{
 		int a = 0;
 	}
@@ -490,7 +493,7 @@ void GLFlat::ProcessSector(sector_t * frontsector)
 	lightlist_t * light;
 
 #ifdef _DEBUG
-	if (frontsector->sectornum==0)
+	if (frontsector->sectornum==gl_breaksec)
 	{
 		int a = 0;
 	}
@@ -639,8 +642,7 @@ void GLFlat::ProcessSector(sector_t * frontsector)
 			if ((rover->flags&(FF_EXISTS|FF_RENDERPLANES|FF_THISINSIDE))==(FF_EXISTS|FF_RENDERPLANES))
 			{
 				if (rover->flags&FF_FOG && gl_fixedcolormap) continue;
-				if (rover->top.copied) continue;	// this plane has been dynamically created and does not produce any rendered surface.
-				if (rover->flags&(FF_INVERTPLANES|FF_BOTHPLANES))
+				if (!rover->top.copied && rover->flags&(FF_INVERTPLANES|FF_BOTHPLANES))
 				{
 					fixed_t ff_top=rover->top.plane->ZatPoint(CenterSpot(sector));
 					if (ff_top<lastceilingheight)
@@ -680,8 +682,7 @@ void GLFlat::ProcessSector(sector_t * frontsector)
 			if ((rover->flags&(FF_EXISTS|FF_RENDERPLANES|FF_THISINSIDE))==(FF_EXISTS|FF_RENDERPLANES))
 			{
 				if (rover->flags&FF_FOG && gl_fixedcolormap) continue;
-				if (rover->bottom.copied) continue;	// this plane has been dynamically created and does not produce any rendered surface.
-				if (rover->flags&(FF_INVERTPLANES|FF_BOTHPLANES))
+				if (!rover->bottom.copied && rover->flags&(FF_INVERTPLANES|FF_BOTHPLANES))
 				{
 					fixed_t ff_bottom=rover->bottom.plane->ZatPoint(CenterSpot(sector));
 					if (ff_bottom>lastfloorheight || (rover->flags&FF_FIX))