From 439c47d3991a69d0aadb0ff2b4c9d6ec05ba708a Mon Sep 17 00:00:00 2001
From: RaveYard <29225776+MrRaveYard@users.noreply.github.com>
Date: Thu, 14 Sep 2023 20:50:33 +0200
Subject: [PATCH] Enforce ZDRay limit on default sampledistance when loading
 LIGHTMAP to avoid surface size mismatches.

---
 src/maploader/maploader.cpp | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/maploader/maploader.cpp b/src/maploader/maploader.cpp
index 938de75bba..ddf0a03d64 100644
--- a/src/maploader/maploader.cpp
+++ b/src/maploader/maploader.cpp
@@ -2963,17 +2963,20 @@ void MapLoader::InitLevelMesh(MapData* map)
 			}
 		}
 	}
-	
-	// Last chance to make up our mind whether to use lightmaps or not
-	if (!Level->lightmaps)
+
+	if (map->Size(ML_LIGHTMAP))
 	{
-		if (map->Size(ML_LIGHTMAP))
+		// Arbitrary ZDRay limit. This will break lightmap lump loading if not enforced.
+		Level->LightmapSampleDistance = Level->LightmapSampleDistance < 8 ? 8 : Level->LightmapSampleDistance;
+
+		if (!Level->lightmaps) // We are unfortunately missing ZDRayInfo
 		{
-			Level->lightmaps = true;
 			Printf(PRINT_HIGH, "InitLevelMesh: The level contains LIGHTMAP, but no ZDRayInfo thing was detected in the level.\n");
 		}
-
-		Level->lightmaps = *genlightmaps;
+	}
+	else
+	{
+		Level->lightmaps = Level->lightmaps || *genlightmaps; // Allow lightmapping in non-lightmapped levels.
 	}
 
 	// Levelmesh and lightmap binding/loading