diff --git a/src/lightmap/levelmesh.cpp b/src/lightmap/levelmesh.cpp
index 462dfc6..762975a 100644
--- a/src/lightmap/levelmesh.cpp
+++ b/src/lightmap/levelmesh.cpp
@@ -178,16 +178,9 @@ void LevelMesh::BuildSmoothingGroups(FLevel& doomMap)
 	printf("Created %d smoothing groups for %d surfaces\n\n", (int)smoothingGroups.size(), (int)surfaces.size());
 }
 
-
-#include <set> // hack
-std::set<Portal, RejectRecursivePortals> touchedPortals;
-
-int depth = 0;
-
 void LevelMesh::PropagateLight(FLevel& doomMap, ThingLight *light)
 {
-	// Because of sectorGroups, this will unlikely get this deep anyway
-	if (depth > 32)
+	if (lightPropagationRecursiveDepth > 32)
 	{
 		return;
 	}
@@ -195,17 +188,17 @@ void LevelMesh::PropagateLight(FLevel& doomMap, ThingLight *light)
 	SphereShape sphere;
 	sphere.center = light->LightRelativeOrigin();
 	sphere.radius = light->LightRadius();
-	depth++;
-	std::set<Portal, RejectRecursivePortals> portalsToErase;
+	lightPropagationRecursiveDepth++;
+	std::set<Portal, RecursivePortalComparator> portalsToErase;
 	for (int triangleIndex : TriangleMeshShape::find_all_hits(Collision.get(), &sphere))
 	{
 		Surface* surface = surfaces[MeshSurfaces[triangleIndex]].get();
-		// Reject any surface which isn't physically connected to the sector group in which the light resided
+
+		// skip any surface which isn't physically connected to the sector group in which the light resides
 		if (light->sectorGroup == surface->sectorGroup)
 		{
 			if (surface->portalIndex >= 0)
 			{			
-
 				auto portal = portals[surface->portalIndex].get();
 
 				if (touchedPortals.insert(*portal).second)
@@ -240,7 +233,8 @@ void LevelMesh::PropagateLight(FLevel& doomMap, ThingLight *light)
 	{
 		touchedPortals.erase(portal);
 	}
-	depth--;
+
+	lightPropagationRecursiveDepth--;
 }
 
 void LevelMesh::BuildLightLists(FLevel& doomMap)
diff --git a/src/lightmap/levelmesh.h b/src/lightmap/levelmesh.h
index 8bc6fd6..9c3add9 100644
--- a/src/lightmap/levelmesh.h
+++ b/src/lightmap/levelmesh.h
@@ -32,6 +32,7 @@
 #include <string>
 #include <cstring>
 #include <map>
+#include <set>
 
 #include "framework/tarray.h"
 #include "framework/halffloat.h"
@@ -154,9 +155,14 @@ public:
 	std::unique_ptr<TriangleMeshShape> Collision;
 
 private:
-	std::vector<std::unique_ptr<ThingLight>> portalLights; // Portal generated lights
+	// Portal to portals[] index
 	std::map<Portal, int, IdenticalPortalComparator> portalCache;
 
+	// Portal lights
+	std::vector<std::unique_ptr<ThingLight>> portalLights;
+	std::set<Portal, RecursivePortalComparator> touchedPortals;
+	int lightPropagationRecursiveDepth = 0;
+
 	void CreateSubsectorSurfaces(FLevel &doomMap);
 	void CreateCeilingSurface(FLevel &doomMap, MapSubsectorEx *sub, IntSector *sector, int typeIndex, bool is3DFloor);
 	void CreateFloorSurface(FLevel &doomMap, MapSubsectorEx *sub, IntSector *sector, int typeIndex, bool is3DFloor);
diff --git a/src/lightmap/portal.h b/src/lightmap/portal.h
index 4f4fe2a..1adcbe9 100644
--- a/src/lightmap/portal.h
+++ b/src/lightmap/portal.h
@@ -20,51 +20,54 @@ struct Portal
 		return vec3(v.x, v.y, v.z);
 	}
 
-	// Check if the portal is inverse
-	inline bool IsInversePortal(const Portal& portal) const
+	// Checks only transformation
+	inline bool IsInverseTransformationPortal(const Portal& portal) const
 	{
 		auto diff = portal.TransformPosition(TransformPosition(vec3(0)));
 		return abs(diff.x) < 0.001 && abs(diff.y) < 0.001 && abs(diff.z) < 0.001;
 	}
 
-	// Check if the portal transformation is equal
-	inline bool IsEqualPortal(const Portal& portal) const
+	// Checks only transformation
+	inline bool IsEqualTransformationPortal(const Portal& portal) const
 	{
 		auto diff = portal.TransformPosition(vec3(0)) - TransformPosition(vec3(0));
 		return (abs(diff.x) < 0.001 && abs(diff.y) < 0.001 && abs(diff.z) < 0.001);
 	}
 
-	// Do both portals travel from sector group A to sector group B?
-	inline bool IsTravelingBetweenSameSectorGroups(const Portal& portal) const
+
+	// Checks transformation, source and destiantion sector groups
+	inline bool IsEqualPortal(const Portal& portal) const
 	{
-		return sourceSectorGroup == portal.sourceSectorGroup && targetSectorGroup == portal.targetSectorGroup;
+		return sourceSectorGroup == portal.sourceSectorGroup && targetSectorGroup == portal.targetSectorGroup && IsEqualTransformationPortal(portal);
+	}
+
+	// Checks transformation, source and destiantion sector groups
+	inline bool IsInversePortal(const Portal& portal) const
+	{
+		return sourceSectorGroup == portal.targetSectorGroup && targetSectorGroup == portal.sourceSectorGroup && IsInverseTransformationPortal(portal);
+	}
+
+	inline void DumpInfo()
+	{
+		auto v = TransformPosition(vec3(0));
+		printf("Portal offset: %.3f %.3f %.3f\n\tsource group:\t%d\n\ttarget group:\t%d", v.x, v.y, v.z, sourceSectorGroup, targetSectorGroup);
 	}
 };
 
-// for use with std::set to recursively go through portals
-struct RejectRecursivePortals
+// for use with std::set to recursively go through portals and skip returning portals
+struct RecursivePortalComparator
 {
-	inline bool IsEqual(const Portal& a, const Portal& b) const
-	{
-		return a.IsInversePortal(b) || a.IsEqualPortal(b);
-	}
-
 	bool operator()(const Portal& a, const Portal& b) const
 	{
-		return !IsEqual(a, b) && std::memcmp(&a.transformation, &b.transformation, sizeof(mat4)) < 0;
+		return !a.IsInversePortal(b) && std::memcmp(&a.transformation, &b.transformation, sizeof(mat4)) < 0;
 	}
 };
 
-// for use with std::map to reject portals which have equal transformation between equal sector groups
+// for use with std::map to reject portals which have the same effect for light rays
 struct IdenticalPortalComparator
 {
-	inline bool IsEqual(const Portal& a, const Portal& b) const
-	{
-		return a.IsEqualPortal(b) && a.IsTravelingBetweenSameSectorGroups(b);
-	}
-
 	bool operator()(const Portal& a, const Portal& b) const
 	{
-		return !IsEqual(a, b) && std::memcmp(&a.transformation, &b.transformation, sizeof(mat4)) < 0;
+		return !a.IsEqualPortal(b) && std::memcmp(&a.transformation, &b.transformation, sizeof(mat4)) < 0;
 	}
 };