From 8cf15a6854f69fbacdb06b574b188d4ae9b5f165 Mon Sep 17 00:00:00 2001
From: SiliconA-Z <gfunni234@gmail.com>
Date: Mon, 9 Mar 2026 11:32:28 -0400
Subject: [PATCH] Document ov5_021D12D0, which clearly handles zone changes in
 distortion world (#995)

---
 include/overlay005/fieldmap.h |  2 +-
 src/overlay005/fieldmap.c     | 15 ++++++---------
 src/overlay009/ov9_02249960.c |  4 ++--
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/include/overlay005/fieldmap.h b/include/overlay005/fieldmap.h
index 621dfee95e..c968ebd668 100644
--- a/include/overlay005/fieldmap.h
+++ b/include/overlay005/fieldmap.h
@@ -8,7 +8,7 @@
 
 extern const ApplicationManagerTemplate gFieldMapTemplate;
 
-void ov5_021D12D0(FieldSystem *fieldSystem, u32 param1);
+void FieldMap_ChangeZoneDistortionWorld(FieldSystem *fieldSystem, u32 mapId);
 void ov5_021D1434(BgConfig *param0);
 void ov5_021D143C(BgConfig *param0);
 void ov5_021D16F4(FieldSystem *fieldSystem, BOOL param1);
diff --git a/src/overlay005/fieldmap.c b/src/overlay005/fieldmap.c
index bad87f1645..72282f91d6 100644
--- a/src/overlay005/fieldmap.c
+++ b/src/overlay005/fieldmap.c
@@ -455,23 +455,20 @@ static BOOL FieldMap_ChangeZone(FieldSystem *fieldSystem)
     return TRUE;
 }
 
-void ov5_021D12D0(FieldSystem *fieldSystem, u32 param1)
+void FieldMap_ChangeZoneDistortionWorld(FieldSystem *fieldSystem, u32 mapId)
 {
-    u32 mapId;
-    FieldOverworldState *fieldState;
+    u32 oldMapId = fieldSystem->location->mapId;
+    FieldOverworldState *fieldState = SaveData_GetFieldOverworldState(fieldSystem->saveData);
 
-    mapId = fieldSystem->location->mapId;
-    fieldState = SaveData_GetFieldOverworldState(fieldSystem->saveData);
+    fieldSystem->location->mapId = mapId;
 
-    fieldSystem->location->mapId = param1;
-
-    MapHeaderData_Load(fieldSystem, param1);
+    MapHeaderData_Load(fieldSystem, mapId);
     FieldMapChange_UpdateGameDataDistortionWorld(fieldSystem, 1);
 
     int objEventCount = MapHeaderData_GetNumObjectEvents(fieldSystem);
     const ObjectEvent *objEventList = MapHeaderData_GetObjectEvents(fieldSystem);
 
-    sub_0206184C(fieldSystem->mapObjMan, mapId, param1, objEventCount, objEventList);
+    sub_0206184C(fieldSystem->mapObjMan, oldMapId, mapId, objEventCount, objEventList);
 
     Sound_TryFadeOutToBGM(fieldSystem, Sound_GetOverrideBGM(fieldSystem, fieldSystem->location->mapId), 1);
     sub_0203A418(fieldSystem);
diff --git a/src/overlay009/ov9_02249960.c b/src/overlay009/ov9_02249960.c
index ffb3eca884..652e5b45ff 100644
--- a/src/overlay009/ov9_02249960.c
+++ b/src/overlay009/ov9_02249960.c
@@ -4717,7 +4717,7 @@ static int ov9_0224CCB8(DistWorldSystem *param0, UnkStruct_ov9_0224CBD8 *param1)
     v2 = GetConnectionsForMap(v2->nextID);
     param1->unk_0C = v2->currID;
 
-    ov5_021D12D0(param0->fieldSystem, param1->unk_0C);
+    FieldMap_ChangeZoneDistortionWorld(param0->fieldSystem, param1->unk_0C);
     ov9_0224BF18(param0, v2->nextID);
     LandDataManager_DistortionWorldEndWithoutFreeing(fieldSystem->landDataMan);
 
@@ -4841,7 +4841,7 @@ static int ov9_0224CEBC(DistWorldSystem *param0, UnkStruct_ov9_0224CBD8 *param1)
 
     param1->unk_0C = v2->currID;
 
-    ov5_021D12D0(param0->fieldSystem, param1->unk_0C);
+    FieldMap_ChangeZoneDistortionWorld(param0->fieldSystem, param1->unk_0C);
     ov9_0224BEB4(param0, param1->unk_0C);
 
     if (v1->unk_10 == NULL) {