diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 0333e979c..8268c12c4 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -1694,6 +1694,7 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 
 		// Used for height comparisons and etc across FOFs and slopes
 		fixed_t high1, highslope1, low1, lowslope1;
+		fixed_t high2, highslope2, low2, lowslope2;
 
 		INT32 texnum;
 		line_t * newline = NULL; // Multi-Property FOF
@@ -1707,18 +1708,6 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 		{
 			for (rover = gl_backsector->ffloors; rover; rover = rover->next)
 			{
-				boolean bothsides = false;
-				// Skip if it exists on both sectors.
-				ffloor_t * r2;
-				for (r2 = gl_frontsector->ffloors; r2; r2 = r2->next)
-					if (rover->master == r2->master)
-					{
-						bothsides = true;
-						break;
-					}
-
-				if (bothsides) continue;
-
 				if (!(rover->fofflags & FOF_EXISTS) || !(rover->fofflags & FOF_RENDERSIDES))
 					continue;
 				if (!(rover->fofflags & FOF_ALLSIDES) && rover->fofflags & FOF_INVERTSIDES)
@@ -1730,6 +1719,45 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 				if ((high1 < lowcut || highslope1 < lowcutslope) || (low1 > highcut || lowslope1 > highcutslope))
 					continue;
 
+				ffloor_t * r2;
+				for (r2 = gl_frontsector->ffloors; r2; r2 = r2->next)
+				{
+					if (r2->master == rover->master) // Skip if same control line.
+						break;
+
+					const ffloortype_e r2flags = r2->fofflags;
+
+					if (!(r2flags & FOF_EXISTS) || !(r2flags & FOF_RENDERSIDES))
+						continue;
+
+					if (rover->fofflags & FOF_EXTRA)
+					{
+						if (!(r2flags & FOF_CUTEXTRA))
+							continue;
+
+						if (r2flags & FOF_EXTRA && (r2flags & (FOF_TRANSLUCENT|FOF_FOG)) != (rover->fofflags & (FOF_TRANSLUCENT|FOF_FOG)))
+							continue;
+					}
+					else
+					{
+						if (!(r2flags & FOF_CUTSOLIDS))
+							continue;
+					}
+
+					SLOPEPARAMS(*r2->t_slope, high2, highslope2, *r2->topheight)
+					SLOPEPARAMS(*r2->b_slope, low2,  lowslope2,  *r2->bottomheight)
+
+					if ((high2 < lowcut || highslope2 < lowcutslope) || (low2 > highcut || lowslope2 > highcutslope))
+						continue;
+					if ((high1 > high2 || highslope1 > highslope2) || (low1 < low2 || lowslope1 < lowslope2))
+						continue;
+
+					break;
+				}
+
+				if (r2)
+					continue;
+
 				texnum = R_GetTextureNum(sides[rover->master->sidenum[0]].midtexture);
 
 				if (rover->master->flags & ML_TFERLINE)
@@ -1867,18 +1895,6 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 		{
 			for (rover = gl_frontsector->ffloors; rover; rover = rover->next)
 			{
-				boolean bothsides = false;
-				// Skip if it exists on both sectors.
-				ffloor_t * r2;
-				for (r2 = gl_backsector->ffloors; r2; r2 = r2->next)
-					if (rover->master == r2->master)
-					{
-						bothsides = true;
-						break;
-					}
-
-				if (bothsides) continue;
-
 				if (!(rover->fofflags & FOF_EXISTS) || !(rover->fofflags & FOF_RENDERSIDES))
 					continue;
 				if (!(rover->fofflags & FOF_ALLSIDES || rover->fofflags & FOF_INVERTSIDES))
@@ -1890,6 +1906,44 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 				if ((high1 < lowcut || highslope1 < lowcutslope) || (low1 > highcut || lowslope1 > highcutslope))
 					continue;
 
+				ffloor_t * r2;
+				for (r2 = gl_backsector->ffloors; r2; r2 = r2->next)
+				{
+					if (r2->master == rover->master) // Skip if same control line.
+						break;
+
+					const ffloortype_e r2flags = r2->fofflags;
+
+					if (!(r2flags & FOF_EXISTS) || !(r2flags & FOF_RENDERSIDES))
+						continue;
+
+					if (rover->fofflags & FOF_EXTRA)
+					{
+						if (!(r2flags & FOF_CUTEXTRA))
+							continue;
+
+						if (r2flags & FOF_EXTRA && (r2flags & (FOF_TRANSLUCENT|FOF_FOG)) != (rover->fofflags & (FOF_TRANSLUCENT|FOF_FOG)))
+							continue;
+					}
+					else
+					{
+						if (!(r2flags & FOF_CUTSOLIDS))
+							continue;
+					}
+
+					SLOPEPARAMS(*r2->t_slope, high2, highslope2, *r2->topheight)
+					SLOPEPARAMS(*r2->b_slope, low2,  lowslope2,  *r2->bottomheight)
+
+					if ((high2 < lowcut || highslope2 < lowcutslope) || (low2 > highcut || lowslope2 > highcutslope))
+						continue;
+					if ((high1 > high2 || highslope1 > highslope2) || (low1 < low2 || lowslope1 < lowslope2))
+						continue;
+
+					break;
+				}
+				if (r2)
+					continue;
+
 				texnum = R_GetTextureNum(sides[rover->master->sidenum[0]].midtexture);
 
 				if (rover->master->flags & ML_TFERLINE)