Mapgen Flat: Fix and improve getSpawnLevelAtPoint() (#8756)

Previously, this wrongly returned ground level (a position containing
a solid node) as spawn level.
Return ground level + 2 (+ 2 to spawn above biome 'dust' nodes).
Improve codestyle and make more consistent with generateTerrain().

diff --git a/src/mapgen/mapgen_flat.cpp b/src/mapgen/mapgen_flat.cpp
index d859fa973012e48a5823766820d1f6c8dfa6db55..773b7b10f188556ce9e0a7cd14c8f35f065caa8f 100644 (file)
--- a/src/mapgen/mapgen_flat.cpp
+++ b/src/mapgen/mapgen_flat.cpp
@@ -143,26 +143,31 @@ void MapgenFlatParams::writeParams(Settings *settings) const
 
 int MapgenFlat::getSpawnLevelAtPoint(v2s16 p)
 {
-       s16 level_at_point = ground_level;
-       float n_terrain = 0.0f;
-       if ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS))
-               n_terrain = NoisePerlin2D(&noise_terrain->np, p.X, p.Y, seed);
+       s16 stone_level = ground_level;
+       float n_terrain = 
+               ((spflags & MGFLAT_LAKES) || (spflags & MGFLAT_HILLS)) ?
+               NoisePerlin2D(&noise_terrain->np, p.X, p.Y, seed) :
+               0.0f;
 
        if ((spflags & MGFLAT_LAKES) && n_terrain < lake_threshold) {
-               level_at_point = ground_level -
-                       (lake_threshold - n_terrain) * lake_steepness;
+               s16 depress = (lake_threshold - n_terrain) * lake_steepness;
+               stone_level = ground_level - depress;
        } else if ((spflags & MGFLAT_HILLS) && n_terrain > hill_threshold) {
-               level_at_point = ground_level +
-                       (n_terrain - hill_threshold) * hill_steepness;
+               s16 rise = (n_terrain - hill_threshold) * hill_steepness;
+               stone_level = ground_level + rise;
        }
 
-       if (ground_level < water_level)  // Ocean world, allow spawn in water
-               return MYMAX(level_at_point, water_level);
+       if (ground_level < water_level)
+               // Ocean world, may not have islands so allow spawn in water
+               return MYMAX(stone_level + 2, water_level);
 
-       if (level_at_point > water_level)
-               return level_at_point;  // Spawn on land
+       if (stone_level >= water_level)
+               // Spawn on land
+               // + 2 not + 1, to spawn above biome 'dust' nodes
+               return stone_level + 2;
 
-       return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
+       // Unsuitable spawn point
+       return MAX_MAP_GENERATION_LIMIT;
 }