Allow swapping lake terrains

For custom lake generations

Author: ehughsbaird

doc/JSON/REGION_SETTINGS.md

@@ -242,6 +242,10 @@ are interpreted.
 | `shore_extendable_overmap_terrain`         | List of overmap terrains that can be extended to the shore if adjacent.     |
 | `shore_extendable_overmap_terrain_aliases` | Overmap terrains to treat as different overmap terrain for extending shore. |
 | `invert_lakes`                             | Invert drawing of lakes. What would be a lake is land, what would be land is a lake. |
+| `shore_ter`                                | Overmap terrain id of shore terrain place on boundary with land. |
+| `surface_ter`                              | Overmap terrain id of surface terrain, placed on z = 0. |
+| `interior_ter`                             | Overmap terrain id of interior terrain, placed between surface terrain and bed terrain. |
+| `bed_ter`                                  | Overmap terrain id of bed terrain, placed on bottom of the lake. |
 
 ### Example
 

src/overmap_water.cpp

@@ -272,11 +272,6 @@ void overmap::place_lakes( const std::vector<const overmap *> &neighbor_overmaps
                settings_lake.invert_lakes ^ omt_lake_noise_threshold( origin, p, noise_threshold );
     };
 
-    const oter_id lake_surface( "lake_surface" );
-    const oter_id lake_shore( "lake_shore" );
-    const oter_id lake_water_cube( "lake_water_cube" );
-    const oter_id lake_bed( "lake_bed" );
-
     // We'll keep track of our visited lake points so we don't repeat the work.
     std::unordered_set<point_om_omt> visited;
 
@@ -357,14 +352,14 @@ void overmap::place_lakes( const std::vector<const overmap *> &neighbor_overmaps
                     }
                 }
 
-                ter_set( tripoint_om_omt( p, 0 ), shore ? lake_shore : lake_surface );
+                ter_set( tripoint_om_omt( p, 0 ), shore ? settings_lake.shore : settings_lake.surface );
 
                 // If this is not a shore, we'll make our subsurface lake cubes and beds.
                 if( !shore ) {
                     for( int z = -1; z > lake_depth; z-- ) {
-                        ter_set( tripoint_om_omt( p, z ), lake_water_cube );
+                        ter_set( tripoint_om_omt( p, z ), settings_lake.interior );
                     }
-                    ter_set( tripoint_om_omt( p, lake_depth ), lake_bed );
+                    ter_set( tripoint_om_omt( p, lake_depth ), settings_lake.bed );
                 }
             }
         }

src/regional_settings.cpp

@@ -21,6 +21,11 @@
 
 class mapgendata;
 
+static const oter_str_id oter_lake_bed( "lake_bed" );
+static const oter_str_id oter_lake_shore( "lake_shore" );
+static const oter_str_id oter_lake_surface( "lake_surface" );
+static const oter_str_id oter_lake_water_cube( "lake_water_cube" );
+
 static const weighted_string_id_reader<overmap_special_id, int> building_bin_reader( 1 );
 static const weighted_string_id_reader<furn_id, int> furn_reader( 1 );
 static const weighted_string_id_reader<ter_id, int> ter_reader( 1 );
@@ -516,6 +521,13 @@ void region_settings_overmap_connection::deserialize( const JsonObject &jo )
     optional( jo, was_loaded, "inter_city_road_connection", inter_city_road_connection );
 }
 
+region_settings_lake::region_settings_lake() :
+    surface( oter_lake_surface ),
+    shore( oter_lake_shore ),
+    interior( oter_lake_water_cube ),
+    bed( oter_lake_bed )
+{}
+
 void region_settings_lake::load( const JsonObject &jo, std::string_view )
 {
     optional( jo, was_loaded, "noise_threshold_lake", noise_threshold_lake );
@@ -527,6 +539,10 @@ void region_settings_lake::load( const JsonObject &jo, std::string_view )
     optional( jo, was_loaded, "shore_extendable_overmap_terrain_aliases",
               shore_extendable_overmap_terrain_aliases );
     optional( jo, was_loaded, "invert_lakes", invert_lakes, false );
+    optional( jo, was_loaded, "surface_ter", surface, oter_lake_surface );
+    optional( jo, was_loaded, "shore_ter", shore, oter_lake_shore );
+    optional( jo, was_loaded, "interior_ter", interior, oter_lake_water_cube );
+    optional( jo, was_loaded, "bed_ter", bed, oter_lake_bed );
 }
 
 void shore_extendable_overmap_terrain_alias::deserialize( const JsonObject &jo )

src/regional_settings.h

@@ -324,6 +324,10 @@ struct region_settings_lake {
     double noise_threshold_lake = 0.25;
     int lake_size_min = 20;
     int lake_depth = -5;
+    oter_str_id surface;
+    oter_str_id shore;
+    oter_str_id interior;
+    oter_str_id bed;
     std::vector<oter_str_id> shore_extendable_overmap_terrain;
     std::vector<shore_extendable_overmap_terrain_alias> shore_extendable_overmap_terrain_aliases;
     bool invert_lakes = false;
@@ -334,7 +338,7 @@ struct region_settings_lake {
 
     static void load_region_settings_lake( const JsonObject &jo, const std::string &src );
     static void reset();
-    region_settings_lake() = default;
+    region_settings_lake();
 };
 
 struct region_settings_ocean {