From aee8a0f76842e2509972a570926c02d37cc32482 Mon Sep 17 00:00:00 2001
From: lahm86 <33758420+lahm86@users.noreply.github.com>
Date: Wed, 5 Feb 2025 13:19:24 +0000
Subject: [PATCH] rooms: introduce utility sector getters

This provides a function to get a room's sector by world X/Z pos, and
another by X/Z index.
---
 src/libtrx/game/rooms/common.c                | 14 ++++++++
 src/libtrx/include/libtrx/game/rooms/common.h |  4 +++
 src/tr1/game/camera/common.c                  | 15 ++++-----
 src/tr1/game/creature.c                       |  9 ++----
 src/tr1/game/inject.c                         |  2 +-
 src/tr1/game/items.c                          |  4 +--
 src/tr1/game/lara/control.c                   |  4 +--
 src/tr1/game/lara/misc.c                      | 10 ++----
 src/tr1/game/lot.c                            |  4 +--
 src/tr1/game/objects/general/door.c           |  2 +-
 src/tr1/game/output.c                         |  2 +-
 src/tr1/game/room.c                           | 32 ++++++-------------
 src/tr2/game/camera.c                         |  9 ++----
 src/tr2/game/creature.c                       | 10 +++---
 src/tr2/game/inject.c                         |  2 +-
 src/tr2/game/items.c                          |  5 ++-
 src/tr2/game/lara/misc.c                      | 13 +++-----
 src/tr2/game/lot.c                            |  4 +--
 src/tr2/game/objects/creatures/diver.c        | 18 ++---------
 src/tr2/game/objects/general/door.c           |  2 +-
 src/tr2/game/objects/general/window.c         | 12 ++-----
 src/tr2/game/room.c                           | 28 +++++-----------
 22 files changed, 76 insertions(+), 129 deletions(-)

diff --git a/src/libtrx/game/rooms/common.c b/src/libtrx/game/rooms/common.c
index 26fa316eb..f4f9e151c 100644
--- a/src/libtrx/game/rooms/common.c
+++ b/src/libtrx/game/rooms/common.c
@@ -278,3 +278,17 @@ BOUNDS_32 Room_GetWorldBounds(void)
 
     return bounds;
 }
+
+SECTOR *Room_GetWorldSector(
+    const ROOM *const room, const int32_t x_pos, const int32_t z_pos)
+{
+    const int32_t x_sector = (x_pos - room->pos.x) >> WALL_SHIFT;
+    const int32_t z_sector = (z_pos - room->pos.z) >> WALL_SHIFT;
+    return Room_GetUnitSector(room, x_sector, z_sector);
+}
+
+SECTOR *Room_GetUnitSector(
+    const ROOM *const room, const int32_t x_sector, const int32_t z_sector)
+{
+    return &room->sectors[z_sector + x_sector * room->size.z];
+}
diff --git a/src/libtrx/include/libtrx/game/rooms/common.h b/src/libtrx/include/libtrx/game/rooms/common.h
index 9aeccb959..555553f4a 100644
--- a/src/libtrx/include/libtrx/game/rooms/common.h
+++ b/src/libtrx/include/libtrx/game/rooms/common.h
@@ -22,3 +22,7 @@ void Room_PopulateSectorData(
 int16_t Room_GetIndexFromPos(int32_t x, int32_t y, int32_t z);
 int32_t Room_FindByPos(int32_t x, int32_t y, int32_t z);
 BOUNDS_32 Room_GetWorldBounds(void);
+
+SECTOR *Room_GetWorldSector(const ROOM *room, int32_t x_pos, int32_t z_pos);
+SECTOR *Room_GetUnitSector(
+    const ROOM *room, int32_t x_sector, int32_t z_sector);
diff --git a/src/tr1/game/camera/common.c b/src/tr1/game/camera/common.c
index 0b065e103..be94a597a 100644
--- a/src/tr1/game/camera/common.c
+++ b/src/tr1/game/camera/common.c
@@ -412,15 +412,14 @@ static void M_SmartShift(
     int32_t z_sector = (g_Camera.target.z - room->pos.z) >> WALL_SHIFT;
     int32_t x_sector = (g_Camera.target.x - room->pos.x) >> WALL_SHIFT;
 
-    const int16_t item_box =
-        room->sectors[z_sector + x_sector * room->size.z].box;
+    const int16_t item_box = Room_GetUnitSector(room, x_sector, z_sector)->box;
     BOX_INFO *box = &g_Boxes[item_box];
 
     room = Room_Get(ideal->room_num);
     z_sector = (ideal->z - room->pos.z) >> WALL_SHIFT;
     x_sector = (ideal->x - room->pos.x) >> WALL_SHIFT;
 
-    int16_t camera_box = room->sectors[z_sector + x_sector * room->size.z].box;
+    int16_t camera_box = Room_GetUnitSector(room, x_sector, z_sector)->box;
     if (camera_box != NO_BOX
         && (ideal->z < box->left || ideal->z > box->right || ideal->x < box->top
             || ideal->x > box->bottom)) {
@@ -436,7 +435,7 @@ static void M_SmartShift(
     const bool bad_left =
         M_BadPosition(ideal->x, ideal->y, test, ideal->room_num);
     if (!bad_left) {
-        camera_box = room->sectors[z_sector - 1 + x_sector * room->size.z].box;
+        camera_box = Room_GetUnitSector(room, x_sector, z_sector - 1)->box;
         if (camera_box != NO_ITEM && g_Boxes[camera_box].left < left) {
             left = g_Boxes[camera_box].left;
         }
@@ -446,7 +445,7 @@ static void M_SmartShift(
     const bool bad_right =
         M_BadPosition(ideal->x, ideal->y, test, ideal->room_num);
     if (!bad_right) {
-        camera_box = room->sectors[z_sector + 1 + x_sector * room->size.z].box;
+        camera_box = Room_GetUnitSector(room, x_sector, z_sector + 1)->box;
         if (camera_box != NO_ITEM && g_Boxes[camera_box].right > right) {
             right = g_Boxes[camera_box].right;
         }
@@ -456,8 +455,7 @@ static void M_SmartShift(
     const bool bad_top =
         M_BadPosition(test, ideal->y, ideal->z, ideal->room_num);
     if (!bad_top) {
-        camera_box =
-            room->sectors[z_sector + (x_sector - 1) * room->size.z].box;
+        camera_box = Room_GetUnitSector(room, x_sector - 1, z_sector)->box;
         if (camera_box != NO_ITEM && g_Boxes[camera_box].top < top) {
             top = g_Boxes[camera_box].top;
         }
@@ -467,8 +465,7 @@ static void M_SmartShift(
     const bool bad_bottom =
         M_BadPosition(test, ideal->y, ideal->z, ideal->room_num);
     if (!bad_bottom) {
-        camera_box =
-            room->sectors[z_sector + (x_sector + 1) * room->size.z].box;
+        camera_box = Room_GetUnitSector(room, x_sector + 1, z_sector)->box;
         if (camera_box != NO_ITEM && g_Boxes[camera_box].bottom > bottom) {
             bottom = g_Boxes[camera_box].bottom;
         }
diff --git a/src/tr1/game/creature.c b/src/tr1/game/creature.c
index 7af10822f..90b99cb73 100644
--- a/src/tr1/game/creature.c
+++ b/src/tr1/game/creature.c
@@ -52,15 +52,12 @@ void Creature_AIInfo(ITEM *item, AI_INFO *info)
     }
 
     const ROOM *room = Room_Get(item->room_num);
-    int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
-    item->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+    item->box_num = Room_GetWorldSector(room, item->pos.x, item->pos.z)->box;
     info->zone_num = zone[item->box_num];
 
     room = Room_Get(g_LaraItem->room_num);
-    z_sector = (g_LaraItem->pos.z - room->pos.z) >> WALL_SHIFT;
-    x_sector = (g_LaraItem->pos.x - room->pos.x) >> WALL_SHIFT;
-    g_LaraItem->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+    g_LaraItem->box_num =
+        Room_GetWorldSector(room, g_LaraItem->pos.x, g_LaraItem->pos.z)->box;
     info->enemy_zone = zone[g_LaraItem->box_num];
 
     if (g_Boxes[g_LaraItem->box_num].overlap_index & creature->lot.block_mask) {
diff --git a/src/tr1/game/inject.c b/src/tr1/game/inject.c
index 9e62ec448..550925423 100644
--- a/src/tr1/game/inject.c
+++ b/src/tr1/game/inject.c
@@ -958,7 +958,7 @@ static void M_FloorDataEdits(INJECTION *injection, LEVEL_INFO *level_info)
                 LOG_WARNING(
                     "Sector [%d,%d] is invalid for room %d", x, z, room_num);
             } else {
-                sector = &room->sectors[room->size.z * x + z];
+                sector = Room_GetUnitSector(room, x, z);
             }
         }
 
diff --git a/src/tr1/game/items.c b/src/tr1/game/items.c
index 445471546..7a372c705 100644
--- a/src/tr1/game/items.c
+++ b/src/tr1/game/items.c
@@ -142,10 +142,8 @@ void Item_Initialise(int16_t item_num)
     ROOM *const room = Room_Get(item->room_num);
     item->next_item = room->item_num;
     room->item_num = item_num;
-    const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
     const SECTOR *const sector =
-        &room->sectors[z_sector + x_sector * room->size.z];
+        Room_GetWorldSector(room, item->pos.x, item->pos.z);
     item->floor = sector->floor.height;
 
     if (g_GameInfo.bonus_flag & GBF_NGPLUS) {
diff --git a/src/tr1/game/lara/control.c b/src/tr1/game/lara/control.c
index 3a566e982..816b56edf 100644
--- a/src/tr1/game/lara/control.c
+++ b/src/tr1/game/lara/control.c
@@ -35,9 +35,7 @@ static void M_WaterCurrent(COLL_INFO *coll)
     ITEM *const item = g_LaraItem;
     const ROOM *const room = Room_Get(item->room_num);
     const SECTOR *const sector =
-        &room->sectors
-             [((item->pos.z - room->pos.z) >> WALL_SHIFT)
-              + ((item->pos.x - room->pos.x) >> WALL_SHIFT) * room->size.z];
+        Room_GetWorldSector(room, item->pos.x, item->pos.z);
     item->box_num = sector->box;
 
     if (Box_CalculateTarget(&target, item, &g_Lara.lot) == TARGET_NONE) {
diff --git a/src/tr1/game/lara/misc.c b/src/tr1/game/lara/misc.c
index 7c5acc730..cde6e900b 100644
--- a/src/tr1/game/lara/misc.c
+++ b/src/tr1/game/lara/misc.c
@@ -656,7 +656,7 @@ int32_t Lara_GetWaterDepth(
             x_sector = room->size.x - 1;
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         if (sector->portal_room.wall == NO_ROOM) {
             break;
         }
@@ -672,9 +672,7 @@ int32_t Lara_GetWaterDepth(
                 sector = Room_GetSector(x, y, z, &room_num);
                 return Room_GetHeight(sector, x, y, z) - water_height;
             }
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         }
         return 0x7FFF;
     }
@@ -686,9 +684,7 @@ int32_t Lara_GetWaterDepth(
             sector = Room_GetSector(x, y, z, &room_num);
             return Room_GetHeight(sector, x, y, z) - water_height;
         }
-        const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetWorldSector(room, x, z);
     }
     return NO_HEIGHT;
 }
diff --git a/src/tr1/game/lot.c b/src/tr1/game/lot.c
index 75b7b3e61..9e46863d3 100644
--- a/src/tr1/game/lot.c
+++ b/src/tr1/game/lot.c
@@ -159,9 +159,7 @@ void LOT_CreateZone(ITEM *item)
     }
 
     const ROOM *const room = Room_Get(item->room_num);
-    const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
-    item->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+    item->box_num = Room_GetWorldSector(room, item->pos.x, item->pos.z)->box;
 
     int16_t zone_num = zone[item->box_num];
     int16_t flip_num = flip[item->box_num];
diff --git a/src/tr1/game/objects/general/door.c b/src/tr1/game/objects/general/door.c
index 42f63a7fd..c74096baf 100644
--- a/src/tr1/game/objects/general/door.c
+++ b/src/tr1/game/objects/general/door.c
@@ -37,7 +37,7 @@ static SECTOR *M_GetRoomRelSector(
         .x = ((item->pos.x - room->pos.x) >> WALL_SHIFT) + sector_dx,
         .z = ((item->pos.z - room->pos.z) >> WALL_SHIFT) + sector_dz,
     };
-    return &room->sectors[sector.x * room->size.z + sector.z];
+    return Room_GetUnitSector(room, sector.x, sector.z);
 }
 
 static void M_Initialise(
diff --git a/src/tr1/game/output.c b/src/tr1/game/output.c
index 435c74f9d..7e1fa4280 100644
--- a/src/tr1/game/output.c
+++ b/src/tr1/game/output.c
@@ -669,7 +669,7 @@ void Output_DrawRoomTriggers(const ROOM *const room)
     S_Output_SetBlendingMode(GFX_BLEND_MODE_NORMAL);
     for (int32_t z = 0; z < room->size.z; z++) {
         for (int32_t x = 0; x < room->size.x; x++) {
-            const SECTOR *sector = &room->sectors[z + x * room->size.z];
+            const SECTOR *sector = Room_GetUnitSector(room, x, z);
             if (sector->trigger == nullptr) {
                 continue;
             }
diff --git a/src/tr1/game/room.c b/src/tr1/game/room.c
index 237360953..9a8fea3a5 100644
--- a/src/tr1/game/room.c
+++ b/src/tr1/game/room.c
@@ -230,9 +230,7 @@ SECTOR *Room_GetPitSector(
 {
     while (sector->portal_room.pit != NO_ROOM) {
         const ROOM *const room = Room_Get(sector->portal_room.pit);
-        const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetWorldSector(room, x, z);
     }
 
     return (SECTOR *)sector;
@@ -243,9 +241,7 @@ static SECTOR *M_GetSkySector(
 {
     while (sector->portal_room.sky != NO_ROOM) {
         const ROOM *const room = Room_Get(sector->portal_room.sky);
-        const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetWorldSector(room, x, z);
     }
 
     return (SECTOR *)sector;
@@ -280,7 +276,7 @@ SECTOR *Room_GetSector(int32_t x, int32_t y, int32_t z, int16_t *room_num)
             x_sector = room->size.x - 1;
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         portal_room = sector->portal_room.wall;
         if (portal_room != NO_ROOM) {
             *room_num = portal_room;
@@ -295,11 +291,8 @@ SECTOR *Room_GetSector(int32_t x, int32_t y, int32_t z, int16_t *room_num)
             }
 
             *room_num = sector->portal_room.pit;
-
             room = Room_Get(sector->portal_room.pit);
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         } while (y >= sector->floor.height);
     } else if (y < sector->ceiling.height) {
         do {
@@ -308,11 +301,8 @@ SECTOR *Room_GetSector(int32_t x, int32_t y, int32_t z, int16_t *room_num)
             }
 
             *room_num = sector->portal_room.sky;
-
             room = Room_Get(sector->portal_room.sky);
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         } while (y < sector->ceiling.height);
     }
 
@@ -472,7 +462,7 @@ int16_t Room_GetWaterHeight(int32_t x, int32_t y, int32_t z, int16_t room_num)
             x_sector = room->size.x - 1;
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         portal_room = sector->portal_room.wall;
         if (portal_room != NO_ROOM) {
             room = Room_Get(portal_room);
@@ -485,9 +475,7 @@ int16_t Room_GetWaterHeight(int32_t x, int32_t y, int32_t z, int16_t room_num)
             if (!(room->flags & RF_UNDERWATER)) {
                 break;
             }
-            z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         }
         return sector->ceiling.height;
     } else {
@@ -496,9 +484,7 @@ int16_t Room_GetWaterHeight(int32_t x, int32_t y, int32_t z, int16_t room_num)
             if (room->flags & RF_UNDERWATER) {
                 return sector->floor.height;
             }
-            z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         }
         return NO_HEIGHT;
     }
@@ -528,7 +514,7 @@ void Room_AlterFloorHeight(ITEM *item, int32_t height)
             CLAMP(x_sector, 0, room->size.x - 1);
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         portal_room = sector->portal_room.wall;
         if (portal_room != NO_ROOM) {
             room = Room_Get(portal_room);
diff --git a/src/tr2/game/camera.c b/src/tr2/game/camera.c
index f44cff3a7..c2fc51413 100644
--- a/src/tr2/game/camera.c
+++ b/src/tr2/game/camera.c
@@ -291,9 +291,8 @@ void Camera_SmartShift(
     LOS_Check(&g_Camera.target, target);
 
     const ROOM *room = Room_Get(g_Camera.target.room_num);
-    int32_t z_sector = (g_Camera.target.z - room->pos.z) >> WALL_SHIFT;
-    int32_t x_sector = (g_Camera.target.x - room->pos.x) >> WALL_SHIFT;
-    int16_t item_box = room->sectors[z_sector + x_sector * room->size.z].box;
+    int16_t item_box =
+        Room_GetWorldSector(room, g_Camera.target.x, g_Camera.target.z)->box;
     const BOX_INFO *box = &g_Boxes[item_box];
 
     int32_t left = (int32_t)box->left << WALL_SHIFT;
@@ -302,9 +301,7 @@ void Camera_SmartShift(
     int32_t bottom = ((int32_t)box->bottom << WALL_SHIFT) - 1;
 
     room = Room_Get(target->room_num);
-    z_sector = (target->z - room->pos.z) >> WALL_SHIFT;
-    x_sector = (target->x - room->pos.x) >> WALL_SHIFT;
-    int16_t camera_box = room->sectors[z_sector + x_sector * room->size.z].box;
+    int16_t camera_box = Room_GetWorldSector(room, target->x, target->z)->box;
 
     if (camera_box != NO_BOX
         && (target->z < left || target->z > right || target->x < top
diff --git a/src/tr2/game/creature.c b/src/tr2/game/creature.c
index 36c94b31f..b303dfe6c 100644
--- a/src/tr2/game/creature.c
+++ b/src/tr2/game/creature.c
@@ -95,17 +95,15 @@ void Creature_AIInfo(ITEM *const item, AI_INFO *const info)
 
     {
         const ROOM *const room = Room_Get(item->room_num);
-        const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
-        item->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+        item->box_num =
+            Room_GetWorldSector(room, item->pos.x, item->pos.z)->box;
         info->zone_num = zone[item->box_num];
     }
 
     {
         const ROOM *const room = Room_Get(enemy->room_num);
-        const int32_t z_sector = (enemy->pos.z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (enemy->pos.x - room->pos.x) >> WALL_SHIFT;
-        enemy->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+        enemy->box_num =
+            Room_GetWorldSector(room, enemy->pos.x, enemy->pos.z)->box;
         info->enemy_zone_num = zone[enemy->box_num];
     }
 
diff --git a/src/tr2/game/inject.c b/src/tr2/game/inject.c
index 11db839f6..13e8d95cf 100644
--- a/src/tr2/game/inject.c
+++ b/src/tr2/game/inject.c
@@ -148,7 +148,7 @@ static void M_FloorDataEdits(
                 LOG_WARNING(
                     "Sector [%d,%d] is invalid for room %d", x, z, room_num);
             } else {
-                sector = &room->sectors[room->size.z * x + z];
+                sector = Room_GetUnitSector(room, x, z);
             }
         }
 
diff --git a/src/tr2/game/items.c b/src/tr2/game/items.c
index 6d570c543..6a445c182 100644
--- a/src/tr2/game/items.c
+++ b/src/tr2/game/items.c
@@ -170,9 +170,8 @@ void Item_Initialise(const int16_t item_num)
     item->next_item = room->item_num;
     room->item_num = item_num;
 
-    const int32_t dx = (item->pos.x - room->pos.x) >> WALL_SHIFT;
-    const int32_t dz = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const SECTOR *const sector = &room->sectors[dx * room->size.z + dz];
+    const SECTOR *const sector =
+        Room_GetWorldSector(room, item->pos.x, item->pos.z);
     item->floor = sector->floor.height;
 
     if (g_SaveGame.bonus_flag && GF_GetCurrentLevel()->type != GFL_DEMO) {
diff --git a/src/tr2/game/lara/misc.c b/src/tr2/game/lara/misc.c
index e0780abd7..aa39a0b3b 100644
--- a/src/tr2/game/lara/misc.c
+++ b/src/tr2/game/lara/misc.c
@@ -1512,7 +1512,7 @@ int32_t Lara_GetWaterDepth(
             x_sector = room->size.x - 1;
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         if (sector->portal_room.wall == NO_ROOM) {
             break;
         }
@@ -1528,9 +1528,7 @@ int32_t Lara_GetWaterDepth(
                 sector = Room_GetSector(x, y, z, &room_num);
                 return Room_GetHeight(sector, x, y, z) - water_height;
             }
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         }
         return 0x7FFF;
     }
@@ -1542,9 +1540,7 @@ int32_t Lara_GetWaterDepth(
             sector = Room_GetSector(x, y, z, &room_num);
             return Room_GetHeight(sector, x, y, z) - water_height;
         }
-        const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetWorldSector(room, x, z);
     }
     return NO_HEIGHT;
 }
@@ -1651,7 +1647,8 @@ void Lara_WaterCurrent(COLL_INFO *const coll)
     const ROOM *const room = Room_Get(g_LaraItem->room_num);
     const int32_t z_sector = (g_LaraItem->pos.z - room->pos.z) >> WALL_SHIFT;
     const int32_t x_sector = (g_LaraItem->pos.x - room->pos.x) >> WALL_SHIFT;
-    g_LaraItem->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+    g_LaraItem->box_num =
+        Room_GetWorldSector(room, g_LaraItem->pos.x, g_LaraItem->pos.z)->box;
 
     if (g_Lara.creature == nullptr) {
         g_Lara.current_active = 0;
diff --git a/src/tr2/game/lot.c b/src/tr2/game/lot.c
index a908f9b19..e3e70e58d 100644
--- a/src/tr2/game/lot.c
+++ b/src/tr2/game/lot.c
@@ -188,9 +188,7 @@ void LOT_CreateZone(ITEM *const item)
     }
 
     const ROOM *const room = Room_Get(item->room_num);
-    const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
-    item->box_num = room->sectors[z_sector + x_sector * room->size.z].box;
+    item->box_num = Room_GetWorldSector(room, item->pos.x, item->pos.z)->box;
 
     int16_t zone_num = zone[item->box_num];
     int16_t flip_num = flip[item->box_num];
diff --git a/src/tr2/game/objects/creatures/diver.c b/src/tr2/game/objects/creatures/diver.c
index 493e649c3..38c0ea26a 100644
--- a/src/tr2/game/objects/creatures/diver.c
+++ b/src/tr2/game/objects/creatures/diver.c
@@ -38,23 +38,11 @@ static const BITE m_DiverBite = {
     .mesh_num = 18,
 };
 
-static const SECTOR *M_GetRelSector(const ROOM *room, int32_t x, int32_t z);
-
-static const SECTOR *M_GetRelSector(
-    const ROOM *const room, const int32_t x, const int32_t z)
-{
-    const XZ_32 sector_pos = {
-        .x = (x - room->pos.x) >> WALL_SHIFT,
-        .z = (z - room->pos.z) >> WALL_SHIFT,
-    };
-    return &room->sectors[sector_pos.z + room->size.z * sector_pos.x];
-}
-
 int32_t Diver_GetWaterSurface(
     const int32_t x, const int32_t y, const int32_t z, const int16_t room_num)
 {
     const ROOM *room = Room_Get(room_num);
-    const SECTOR *sector = M_GetRelSector(room, x, z);
+    const SECTOR *sector = Room_GetWorldSector(room, x, z);
 
     if ((room->flags & RF_UNDERWATER)) {
         while (sector->portal_room.sky != NO_ROOM) {
@@ -62,7 +50,7 @@ int32_t Diver_GetWaterSurface(
             if (!(room->flags & RF_UNDERWATER)) {
                 return sector->ceiling.height;
             }
-            sector = M_GetRelSector(room, x, z);
+            sector = Room_GetWorldSector(room, x, z);
         }
     } else {
         while (sector->portal_room.pit != NO_ROOM) {
@@ -70,7 +58,7 @@ int32_t Diver_GetWaterSurface(
             if ((room->flags & RF_UNDERWATER)) {
                 return sector->floor.height;
             }
-            sector = M_GetRelSector(room, x, z);
+            sector = Room_GetWorldSector(room, x, z);
         }
     }
     return NO_HEIGHT;
diff --git a/src/tr2/game/objects/general/door.c b/src/tr2/game/objects/general/door.c
index 30d270024..d8728e88a 100644
--- a/src/tr2/game/objects/general/door.c
+++ b/src/tr2/game/objects/general/door.c
@@ -32,7 +32,7 @@ static SECTOR *M_GetRoomRelSector(
         .x = ((item->pos.x - room->pos.x) >> WALL_SHIFT) + sector_dx,
         .z = ((item->pos.z - room->pos.z) >> WALL_SHIFT) + sector_dz,
     };
-    return &room->sectors[sector.x * room->size.z + sector.z];
+    return Room_GetUnitSector(room, sector.x, sector.z);
 }
 
 static void M_Initialise(
diff --git a/src/tr2/game/objects/general/window.c b/src/tr2/game/objects/general/window.c
index 4ba12277a..968147f78 100644
--- a/src/tr2/game/objects/general/window.c
+++ b/src/tr2/game/objects/general/window.c
@@ -38,10 +38,8 @@ void Window_Initialise(const int16_t item_num)
     item->mesh_bits = 1;
 
     const ROOM *const room = Room_Get(item->room_num);
-    const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
     const SECTOR *const sector =
-        &room->sectors[z_sector + x_sector * room->size.z];
+        Room_GetWorldSector(room, item->pos.x, item->pos.z);
     BOX_INFO *const box = &g_Boxes[sector->box];
 
     if (box->overlap_index & BOX_BLOCKABLE) {
@@ -79,10 +77,8 @@ void Window_2_Control(const int16_t item_num)
     }
 
     const ROOM *const room = Room_Get(item->room_num);
-    const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
     const SECTOR *const sector =
-        &room->sectors[z_sector + x_sector * room->size.z];
+        Room_GetWorldSector(room, item->pos.x, item->pos.z);
     BOX_INFO *const box = &g_Boxes[sector->box];
 
     if (box->overlap_index & BOX_BLOCKED) {
@@ -103,10 +99,8 @@ void Window_Smash(const int16_t item_num)
 {
     ITEM *const item = Item_Get(item_num);
     const ROOM *const room = Room_Get(item->room_num);
-    const int32_t z_sector = (item->pos.z - room->pos.z) >> WALL_SHIFT;
-    const int32_t x_sector = (item->pos.x - room->pos.x) >> WALL_SHIFT;
     const SECTOR *const sector =
-        &room->sectors[z_sector + x_sector * room->size.z];
+        Room_GetWorldSector(room, item->pos.x, item->pos.z);
     BOX_INFO *const box = &g_Boxes[sector->box];
 
     if (box->overlap_index & BOX_BLOCKABLE) {
diff --git a/src/tr2/game/room.c b/src/tr2/game/room.c
index 131b32b16..491991fc7 100644
--- a/src/tr2/game/room.c
+++ b/src/tr2/game/room.c
@@ -494,9 +494,7 @@ SECTOR *Room_GetPitSector(
 {
     while (sector->portal_room.pit != NO_ROOM) {
         const ROOM *const room = Room_Get(sector->portal_room.pit);
-        const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetWorldSector(room, x, z);
     }
 
     return (SECTOR *)sector;
@@ -507,9 +505,7 @@ SECTOR *Room_GetSkySector(
 {
     while (sector->portal_room.sky != NO_ROOM) {
         const ROOM *const room = Room_Get(sector->portal_room.sky);
-        const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-        const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetWorldSector(room, x, z);
     }
 
     return (SECTOR *)sector;
@@ -545,7 +541,7 @@ SECTOR *Room_GetSector(
             x_sector = room->size.x - 1;
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         if (sector->portal_room.wall == NO_ROOM) {
             break;
         }
@@ -558,9 +554,7 @@ SECTOR *Room_GetSector(
         while (sector->portal_room.pit != NO_ROOM) {
             *room_num = sector->portal_room.pit;
             const ROOM *const room = Room_Get(*room_num);
-            const int32_t z_sector = ((z - room->pos.z) >> WALL_SHIFT);
-            const int32_t x_sector = ((x - room->pos.x) >> WALL_SHIFT);
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
             if (y < sector->floor.height) {
                 break;
             }
@@ -569,9 +563,7 @@ SECTOR *Room_GetSector(
         while (sector->portal_room.sky != NO_ROOM) {
             *room_num = sector->portal_room.sky;
             const ROOM *const room = Room_Get(sector->portal_room.sky);
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
             if (y >= sector->ceiling.height) {
                 break;
             }
@@ -612,7 +604,7 @@ int32_t Room_GetWaterHeight(
             x_sector = room->size.x - 1;
         }
 
-        sector = &room->sectors[z_sector + x_sector * room->size.z];
+        sector = Room_GetUnitSector(room, x_sector, z_sector);
         room_num = sector->portal_room.wall;
     } while (room_num != NO_ROOM);
 
@@ -622,9 +614,7 @@ int32_t Room_GetWaterHeight(
             if (!(room->flags & RF_UNDERWATER)) {
                 break;
             }
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         }
         return sector->ceiling.height;
     } else {
@@ -633,9 +623,7 @@ int32_t Room_GetWaterHeight(
             if (room->flags & RF_UNDERWATER) {
                 return sector->floor.height;
             }
-            const int32_t z_sector = (z - room->pos.z) >> WALL_SHIFT;
-            const int32_t x_sector = (x - room->pos.x) >> WALL_SHIFT;
-            sector = &room->sectors[z_sector + x_sector * room->size.z];
+            sector = Room_GetWorldSector(room, x, z);
         }
         return NO_HEIGHT;
     }