fixes outpost baseturfs

code/modules/mapping/map_template.dm

@@ -7,7 +7,11 @@
 	var/datum/parsed_map/cached_map
 	var/keep_cached_map = FALSE
 
-	///if true, turfs loaded from this template are placed on top of the turfs already there, defaults to TRUE
+	/// Defaults to TRUE.
+	/// If TRUE, the baseturfs of the new turfs (ignoring baseturf_bottom and space) are added
+	/// to the top of the pre-existing baseturf lists, in accordance with the behavior of PlaceOnTop.
+	/// If FALSE, the old turfs are replaced entirely, including their baseturfs.
+	/// Note that FALSE-case behavior is altered from the original implementation, which ignored baseturfs entirely; it was intended for holodecks, which have been removed.
 	var/should_place_on_top = TRUE
 
 	///if true, creates a list of all atoms created by this template loading, defaults to FALSE

code/modules/mapping/reader.dm

@@ -494,14 +494,15 @@ GLOBAL_LIST_EMPTY(map_model_default)
 		if(members_attributes[index] != default_list)
 			world.preloader_setup(members_attributes[index], members[index])
 
+		var/turf/new_turf_type = members[index]
 		// Note: we make the assertion that the last path WILL be a turf. if it isn't, this will fail.
 		var/old_virtual_z = crds.virtual_z
 		if(placeOnTop)
-			instance = crds.PlaceOnTop(null, members[index], CHANGETURF_DEFER_CHANGE | (no_changeturf ? CHANGETURF_SKIP : NONE))
+			instance = crds.PlaceOnTop(null, new_turf_type, CHANGETURF_DEFER_CHANGE | (no_changeturf ? CHANGETURF_SKIP : NONE))
 		else if(!no_changeturf)
-			instance = crds.ChangeTurf(members[index], null, CHANGETURF_DEFER_CHANGE)
+			instance = crds.ChangeTurf(new_turf_type, initial(new_turf_type.baseturfs), CHANGETURF_DEFER_CHANGE)
 		else
-			instance = create_turf(members[index], crds , old_virtual_z)//first preloader pass
+			instance = create_turf(new_turf_type, crds , old_virtual_z)//first preloader pass
 		var/turf/new_turf = instance
 		new_turf.virtual_z = old_virtual_z //UNDER NO CIRCUMSTANCES LOOSE THIS VARIABLE
 

code/modules/overmap/objects/outpost/outpost_types.dm

@@ -3,9 +3,6 @@
 */
 
 /datum/map_template/outpost
-	// ! TODO: change build_coordinate so that placeOnTop == FALSE passes new turf's baseturfs to ChangeTurf.
-	// ! this would cause maploading a should_place_on_top == FALSE template to reset the baseturfs to those of the turf instead of
-	// ! causing it to CLEAR the turf's baseturfs. this will require a holodeck removal, as they're the main thing that uses should_place_on_top == FALSE
 	// Necessary to stop planetary outposts from having space underneath all their turfs.
 	// They were being "placed on top", so instead of their baseturf, there was just space underneath.
 	// (Interestingly, this is much less of a problem for ruins: PlaceOnTop ignores the top closed turf in the baseturfs stack