tr1/carrier: fix initial sector selection for falling items

This ensures that if an item is dropped exactly at the height of a
vertical portal, we get the room just above that portal first to ensure
that later the item is placed in the correct room, and hence drawn
there.

Resolves #2088.

docs/tr1/CHANGELOG.md

@@ -1,4 +1,5 @@
 ## [Unreleased](https://github.com/LostArtefacts/TRX/compare/tr1-4.7...develop) - ××××-××-××
+- fixed falling pickup items not being drawn when they land in rare cases (#2088)
 
 ## [4.7](https://github.com/LostArtefacts/TRX/compare/tr1-4.6.1...tr1-4.7) - 2024-12-20
 - added support for Wayland in binary Linux builds (#1927)

src/tr1/game/carrier.c

@@ -79,8 +79,11 @@ static void M_AnimateDrop(CARRIED_ITEM *const item)
 
     ITEM *const pickup = Item_Get(item->spawn_num);
     int16_t room_num = pickup->room_num;
-    const SECTOR *const sector =
-        Room_GetSector(pickup->pos.x, pickup->pos.y, pickup->pos.z, &room_num);
+    // For cases where a flyer has dropped an item exactly on a portal, we need
+    // to ensure that the initial sector is in the room above, hence we test
+    // slightly above the initial y position.
+    const SECTOR *const sector = Room_GetSector(
+        pickup->pos.x, pickup->pos.y - 10, pickup->pos.z, &room_num);
     const int16_t height =
         Room_GetHeight(sector, pickup->pos.x, pickup->pos.y, pickup->pos.z);
     const bool in_water = g_RoomInfo[pickup->room_num].flags & RF_UNDERWATER;