feat: smooth underwater shore (#3938)

* Underwater shore

* Shut up linter

data/json/overmap/overmap_terrain/overmap_terrain_waterbody.json

@@ -10,6 +10,17 @@
     "flags": [ "NO_ROTATE", "LAKE_SHORE", "SOURCE_DRINK" ],
     "mapgen": [ { "method": "builtin", "name": "lake_shore" } ]
   },
+  {
+    "type": "overmap_terrain",
+    "id": "lake_underwater_shore",
+    "copy-from": "generic_water",
+    "name": "lake shore (submerged)",
+    "sym": "#",
+    "color": "light_blue",
+    "see_cost": 1,
+    "flags": [ "NO_ROTATE", "LAKE_SHORE", "SOURCE_DRINK" ],
+    "mapgen": [ { "method": "builtin", "name": "lake_shore" } ]
+  },
   {
     "type": "overmap_terrain",
     "id": "lake_surface",

src/mapdata.cpp

@@ -697,7 +697,7 @@ ter_id t_null,
        t_fungus_mound, t_fungus, t_shrub_fungal, t_tree_fungal, t_tree_fungal_young, t_marloss_tree,
        // Water, lava, etc.
        t_water_moving_dp, t_water_moving_sh, t_water_sh, t_water_dp, t_swater_sh, t_swater_dp,
-       t_water_pool, t_sewage,
+       t_water_cube, t_lake_bed, t_water_pool, t_sewage,
        t_lava,
        // More embellishments than you can shake a stick at.
        t_sandbox, t_slide, t_monkey_bars, t_backboard,
@@ -948,6 +948,8 @@ void set_ter_ids()
     t_water_dp = ter_id( "t_water_dp" );
     t_swater_sh = ter_id( "t_swater_sh" );
     t_swater_dp = ter_id( "t_swater_dp" );
+    t_water_cube = ter_id( "t_water_cube" );
+    t_lake_bed  = ter_id( "t_lake_bed" );
     t_water_pool = ter_id( "t_water_pool" );
     t_sewage = ter_id( "t_sewage" );
     t_lava = ter_id( "t_lava" );

src/mapdata.h

@@ -711,7 +711,7 @@ extern ter_id t_null,
        t_fungus_mound, t_fungus, t_shrub_fungal, t_tree_fungal, t_tree_fungal_young, t_marloss_tree,
        // Water, lava, etc.
        t_water_moving_dp, t_water_moving_sh, t_water_sh, t_swater_sh, t_water_dp, t_swater_dp,
-       t_water_pool, t_sewage,
+       t_water_cube, t_lake_bed, t_water_pool, t_sewage,
        t_lava,
        // More embellishments than you can shake a stick at.
        t_sandbox, t_slide, t_monkey_bars, t_backboard,

src/mapgen_functions.cpp

@@ -16,6 +16,7 @@
 #include "enums.h"
 #include "field_type.h"
 #include "flood_fill.h"
+#include "game.h"
 #include "game_constants.h"
 #include "int_id.h"
 #include "line.h"
@@ -2587,7 +2588,11 @@ void mapgen_lake_shore( mapgendata &dat )
     // If we didn't extend an adjacent terrain, then just fill this entire location with the default
     // groundcover for the region.
     if( !did_extend_adjacent_terrain ) {
-        dat.fill_groundcover();
+        if( dat.zlevel() >= 0 ) {
+            dat.fill_groundcover();
+        } else {
+            fill_background( m, t_rock );
+        }
     }
 
     const oter_id river_center( "river_center" );
@@ -2867,15 +2872,27 @@ void mapgen_lake_shore( mapgendata &dat )
         }
     };
 
+    // We need to have same shoreline on different z levels, to match surface shore
+    // with submerged shore, to do so we'll jitter shore lines using deterministic
+    // random seeded with x\y coordinates
+    // NOLINTNEXTLINE(cata-determinism)
+    std::mt19937 prng( std::hash<point_abs_omt>()( dat.pos.xy() ) ^ g->get_seed() );
+
     // Given two points, return a point that is midway between the two points and then
     // jittered by a random amount in proportion to the length of the line segment.
     const auto jittered_midpoint = [&]( point  from, point  to ) {
         const int jitter = rl_dist( from, to ) / 4;
-        const point midpoint( ( from.x + to.x ) / 2 + rng( -jitter, jitter ),
-                              ( from.y + to.y ) / 2 + rng( -jitter, jitter ) );
+        std::uniform_int_distribution<int> roll( -jitter, jitter );
+        const point midpoint( ( from.x + to.x ) / 2 + roll( prng ),
+                              ( from.y + to.y ) / 2 + roll( prng ) );
         return midpoint;
     };
 
+    ter_id edge_tile = dat.zlevel() >= 0 ? t_water_sh : t_rock;
+    ter_id water_tile = dat.zlevel() >= 0 ? t_water_dp :
+                        dat.zlevel() == dat.region.overmap_lake.lake_depth ? t_lake_bed :
+                        t_water_cube;
+
     // For each of our valid shoreline line segments, generate a slightly more interesting
     // set of line segments by splitting the line into four segments with jittered
     // midpoints, and then draw shallow water for four each of those.
@@ -2906,7 +2923,7 @@ void mapgen_lake_shore( mapgendata &dat )
         std::vector<point> water_points = ff::point_flood_fill_4_connected( starting_point, visited,
                                           should_fill );
         for( auto &wp : water_points ) {
-            m->ter_set( wp, t_water_dp );
+            m->ter_set( wp, water_tile );
             m->furn_set( wp, f_null );
         }
     };
@@ -2931,7 +2948,7 @@ void mapgen_lake_shore( mapgendata &dat )
 
     // We previously placed our shallow water but actually did a t_null instead to make sure that we didn't
     // pick up shallow water from our extended terrain. Now turn those nulls into t_water_sh.
-    m->translate( t_null, t_water_sh );
+    m->translate( t_null, edge_tile );
 }
 
 void mremove_trap( map *m, point p )

src/mapgendata.cpp

@@ -34,7 +34,7 @@ mapgendata::mapgendata( map &mp, dummy_settings_t )
     : density_( 0 )
     , when_( calendar::turn )
     , mission_( nullptr )
-    , zlevel_( 0 )
+    , pos( tripoint_zero )
     , region( dummy_regional_settings )
     , m( mp )
     , default_groundcover( region.default_groundcover )
@@ -50,9 +50,9 @@ mapgendata::mapgendata( const tripoint_abs_omt &over, map &mp, const float densi
     , density_( density )
     , when_( when )
     , mission_( miss )
-    , zlevel_( over.z() )
     , t_above( overmap_buffer.ter( over + tripoint_above ) )
     , t_below( overmap_buffer.ter( over + tripoint_below ) )
+    , pos( over )
     , region( overmap_buffer.get_settings( over ) )
     , m( mp )
     , default_groundcover( region.default_groundcover )

src/mapgendata.h

@@ -69,7 +69,6 @@ class mapgendata
         float density_;
         time_point when_;
         ::mission *mission_;
-        int zlevel_;
         mapgen_arguments mapgen_args_;
 
     public:
@@ -89,6 +88,7 @@ class mapgendata
 
         std::unordered_map<cube_direction, std::string> joins;
 
+        const tripoint_abs_omt pos;
         const regional_settings &region;
 
         map &m;
@@ -135,8 +135,7 @@ class mapgendata
             return mission_;
         }
         int zlevel() const {
-            // TODO: should be able to determine this from the map itself
-            return zlevel_;
+            return pos.z();
         }
 
         void set_dir( int dir_in, int val );

src/overmap.cpp

@@ -4100,6 +4100,7 @@ void overmap::place_lakes()
 
     const oter_id lake_surface( "lake_surface" );
     const oter_id lake_shore( "lake_shore" );
+    const oter_id lake_underwater_shore( "lake_underwater_shore" );
     const oter_id lake_water_cube( "lake_water_cube" );
     const oter_id lake_bed( "lake_bed" );
 
@@ -4178,6 +4179,10 @@ void overmap::place_lakes()
                         ter_set( tripoint_om_omt( p, z ), lake_water_cube );
                     }
                     ter_set( tripoint_om_omt( p, settings->overmap_lake.lake_depth ), lake_bed );
+                } else {
+                    for( int z = -1; z >= settings->overmap_lake.lake_depth; z-- ) {
+                        ter_set( tripoint_om_omt( p, z ), lake_underwater_shore );
+                    }
                 }
             }