mark old tiles for update

src/playsim/a_dynlight.cpp

@@ -758,6 +758,8 @@ void FDynamicLight::CollectWithinRadius(const DVector3 &opos, FSection *section,
 
 void FDynamicLight::LinkLight()
 {
+	bool markTiles = (Trace() && Level->levelMesh);
+
 	// mark the old light nodes
 	FLightNode * node;
 	
@@ -787,27 +789,62 @@ void FDynamicLight::LinkLight()
 		
 	// Now delete any nodes that won't be used. These are the ones where
 	// m_thing is still nullptr.
-	
-	node = touching_sides;
-	while (node)
-	{
-		if (node->lightsource == nullptr)
-		{
-			node = DeleteLightNode(node);
-		}
-		else
-			node = node->nextTarget;
-	}
 
-	node = touching_sector;
-	while (node)
+	if(markTiles)
 	{
-		if (node->lightsource == nullptr)
+		node = touching_sides;
+		while (node)
 		{
-			node = DeleteLightNode(node);
+			if (node->lightsource == nullptr)
+			{
+				MarkTilesForUpdate(Level, node->targLine->LightmapTiles);
+
+				node = DeleteLightNode(node);
+			}
+			else
+				node = node->nextTarget;
+		}
+
+		node = touching_sector;
+		while (node)
+		{
+			if (node->lightsource == nullptr)
+			{
+				for(subsector_t * ss : static_cast<FSection *>(node->targ)->subsectors)
+				{
+					MarkTilesForUpdate(Level, ss->LightmapTiles[0]);
+					MarkTilesForUpdate(Level, ss->LightmapTiles[1]);
+				}
+
+				node = DeleteLightNode(node);
+			}
+			else
+				node = node->nextTarget;
+		}
+	}
+	else
+	{
+		node = touching_sides;
+		while (node)
+		{
+			if (node->lightsource == nullptr)
+			{
+				node = DeleteLightNode(node);
+			}
+			else
+				node = node->nextTarget;
+		}
+
+		node = touching_sector;
+		while (node)
+		{
+			if (node->lightsource == nullptr)
+			{
+				node = DeleteLightNode(node);
+			}
+			else
+				node = node->nextTarget;
 		}
-		else
-			node = node->nextTarget;
 	}
 }