Get roofs generated for basecamps

src/map.h

@@ -2396,6 +2396,9 @@ bool generate_uniform_omt( const tripoint_abs_sm &p, const oter_id &terrain_type
 class tinymap : private map
 {
         friend class editmap;
+    protected:
+        tinymap( int mapsize, bool zlev ) : map( mapsize, zlev ) {};
+
     public:
         tinymap() : map( 2, false ) {}
         bool inbounds( const tripoint &p ) const override;
@@ -2637,4 +2640,18 @@ class fake_map : public tinymap
         ~fake_map() override;
         static constexpr int fake_map_z = -OVERMAP_DEPTH;
 };
+
+/**
+* Smallmap is similar to tinymap in that it covers a single overmap terrain (OMT) tile, but differs
+* from it in that it covers all Z levels, not just a single one. It's intended usage is for cases
+* where you need to operate on an OMT, but cannot guarantee you needs are restricted to a single
+* Z level.
+* The smallmap's natural relative reference system is the tripoint_omt_ms one.
+*/
+class smallmap : public tinymap
+{
+    public:
+        smallmap() : tinymap( 2, true ) {}
+        void add_roofs();
+};
 #endif // CATA_SRC_MAP_H

src/mapgen.cpp

@@ -7688,27 +7688,36 @@ bool update_mapgen_function_json::update_map(
         return false;
     }
 
-    std::unique_ptr<tinymap> p_update_tmap = std::make_unique<tinymap>();
-    tinymap &update_tmap = *p_update_tmap;
+    std::unique_ptr<smallmap> p_update_smap = std::make_unique<smallmap>();
+    smallmap &update_smap = *p_update_smap;
 
-    update_tmap.load( omt_pos, true );
-    update_tmap.rotate( 4 - rotation );
-    update_tmap.mirror( mirror_horizontal, mirror_vertical );
+    update_smap.load( omt_pos, true );
+    update_smap.rotate( 4 - rotation );
+    update_smap.mirror( mirror_horizontal, mirror_vertical );
 
-    mapgendata md_base( omt_pos, *update_tmap.cast_to_map(), 0.0f, calendar::start_of_cataclysm, miss );
+    mapgendata md_base( omt_pos, *update_smap.cast_to_map(), 0.0f, calendar::start_of_cataclysm, miss );
     mapgendata md( md_base, args );
 
     bool const u = update_map( md, offset, verify );
-    update_tmap.mirror( mirror_horizontal, mirror_vertical );
-    update_tmap.rotate( rotation );
+    update_smap.mirror( mirror_horizontal, mirror_vertical );
+    update_smap.rotate( rotation );
 
     if( get_map().inbounds( project_to<coords::ms>( omt_pos ) ) ) {
         // trigger main map cleanup
-        p_update_tmap.reset();
+        p_update_smap.reset();
         // trigger new traps, etc
         g->place_player( get_avatar().pos(), true );
     }
 
+    // Trigger magic to add roofs (within load) if needed.
+    if( omt_pos.z() < OVERMAP_HEIGHT ) {
+        std::unique_ptr<smallmap> p_roof_smap = std::make_unique<smallmap>();
+        smallmap &roof_smap = *p_roof_smap;
+        // The loading of the Z level above is not necessary, but looks better.
+        const tripoint_abs_omt omt_above = { omt_pos.x(), omt_pos.y(), omt_pos.z() + 1 };
+        roof_smap.load( omt_above, false );
+    }
+
     return u;
 }