From 5d3f16b0d60286e6a4db5073aa783824d6a9d2f9 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Mon, 12 May 2025 13:41:51 +0200
Subject: [PATCH] Only update VBO lightmap if its a full update

---
 src/rendering/hwrenderer/doom_levelmesh.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/rendering/hwrenderer/doom_levelmesh.cpp b/src/rendering/hwrenderer/doom_levelmesh.cpp
index 96af2c278..8ff8ce032 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.cpp
+++ b/src/rendering/hwrenderer/doom_levelmesh.cpp
@@ -346,14 +346,17 @@ void DoomLevelMesh::BeginFrame(FLevelLocals& doomMap)
 		{
 			CreateFlat(doomMap, flatIndex);
 		}
-		Flats[flatIndex].UpdateType = SurfaceUpdateType::None;
 	}
 
 	PackLightmapAtlas();
 
 	for (int flatIndex : FlatUpdateList)
 	{
-		UpdateVBOLightmap(*screen->RenderState(), &doomMap.sectors[flatIndex]);
+		if (Flats[flatIndex].UpdateType == SurfaceUpdateType::Full)
+		{
+			UpdateVBOLightmap(*screen->RenderState(), &doomMap.sectors[flatIndex]);
+		}
+		Flats[flatIndex].UpdateType = SurfaceUpdateType::None;
 	}
 	FlatUpdateList.Clear();