Add weights to biomes (#15142)

builtin/game/features.lua

@@ -43,6 +43,7 @@ core.features = {
 	hotbar_hud_element = true,
 	bulk_lbms = true,
 	abm_without_neighbors = true,
+	biome_weights = true,
 }
 
 function core.has_feature(arg)

doc/lua_api.md

@@ -5657,6 +5657,8 @@ Utilities
       bulk_lbms = true,
       -- ABM supports field without_neighbors (5.10.0)
       abm_without_neighbors = true,
+      -- biomes have a weight parameter (5.11.0)
+      biome_weights = true,
   }
   ```
 
@@ -10709,6 +10711,10 @@ performance and computing power the practical limit is much lower.
     -- distribution of the biomes.
     -- Heat and humidity have average values of 50, vary mostly between
     -- 0 and 100 but can exceed these values.
+
+    weight = 1.0,
+    -- Relative weight of the biome in the Voronoi diagram.
+    -- A value of 0 (or less) is ignored and equivalent to 1.0.
 }
 ```
 

src/mapgen/mg_biome.cpp

@@ -39,6 +39,7 @@ BiomeManager::BiomeManager(Server *server) :
 	b->heat_point      = 0.0;
 	b->humidity_point  = 0.0;
 	b->vertical_blend  = 0;
+	b->weight          = 1.0f;
 
 	b->m_nodenames.emplace_back("mapgen_stone");
 	b->m_nodenames.emplace_back("mapgen_stone");
@@ -256,7 +257,9 @@ Biome *BiomeGenOriginal::calcBiomeFromNoise(float heat, float humidity, v3s16 po
 
 		float d_heat = heat - b->heat_point;
 		float d_humidity = humidity - b->humidity_point;
-		float dist = (d_heat * d_heat) + (d_humidity * d_humidity);
+		float dist = ((d_heat * d_heat) + (d_humidity * d_humidity));
+		if (b->weight > 0.f)
+		       dist /= b->weight;
 
 		if (pos.Y <= b->max_pos.Y) { // Within y limits of biome b
 			if (dist < dist_min) {
@@ -321,6 +324,7 @@ ObjDef *Biome::clone() const
 	obj->heat_point = heat_point;
 	obj->humidity_point = humidity_point;
 	obj->vertical_blend = vertical_blend;
+	obj->weight = weight;
 
 	return obj;
 }

src/mapgen/mg_biome.h

@@ -54,6 +54,7 @@ public:
 	float heat_point;
 	float humidity_point;
 	s16 vertical_blend;
+	float weight;
 
 	virtual void resolveNodeNames();
 };

src/script/lua_api/l_mapgen.cpp

@@ -374,6 +374,7 @@ Biome *read_biome_def(lua_State *L, int index, const NodeDefManager *ndef)
 	b->heat_point      = getfloatfield_default(L,  index, "heat_point",      0.f);
 	b->humidity_point  = getfloatfield_default(L,  index, "humidity_point",  0.f);
 	b->vertical_blend  = getintfield_default(L,    index, "vertical_blend",  0);
+	b->weight          = getfloatfield_default(L,  index, "weight",          1.f);
 	b->flags           = 0; // reserved
 
 	b->min_pos = getv3s16field_default(