add biome 'parameters' field

res/generators/default.lua

@@ -5,6 +5,10 @@ sea_level = 64
 biome_parameters = 2
 
 biome = {
+    parameters = {
+        {value=0.5, weight=1.0},
+        {value=0.5, weight=1.0},
+    },
     sea_layers = {
         {block="base:water", height=-1},
     },

src/logic/scripting/lua/lua_util.hpp

@@ -566,7 +566,7 @@ namespace lua {
     ) {
         requirefield(L, name, idx);
         auto value = require_string(L, -1);
-        lua::pop(L);
+        pop(L);
         return value;
     }
 
@@ -575,7 +575,16 @@ namespace lua {
     ) {
         requirefield(L, name, idx);
         auto value = tointeger(L, -1);
-        lua::pop(L);
+        pop(L);
+        return value;
+    }
+
+    inline Number require_number_field(
+        lua::State* L, const std::string& name, int idx=-1
+    ) {
+        requirefield(L, name, idx);
+        auto value = tonumber(L, -1);
+        pop(L);
         return value;
     }
 

src/logic/scripting/scripting_world_generation.cpp

@@ -112,9 +112,25 @@ static inline BlocksLayers load_layers(
 }
 
 static inline Biome load_biome(
-    lua::State* L, const std::string& name, int idx
+    lua::State* L, const std::string& name, uint parametersCount, int idx
 ) {
     lua::pushvalue(L, idx);
+
+    std::vector<BiomeParameter> parameters(parametersCount);
+    lua::requirefield(L, "parameters");
+    if (lua::objlen(L, -1) < parametersCount) {
+        throw std::runtime_error(
+            std::to_string(parametersCount)+" parameters expected");
+    }
+    for (uint i = 1; i <= parametersCount; i++) {
+        lua::rawgeti(L, i);
+        float value = lua::require_number_field(L, "value");
+        float weight = lua::require_number_field(L, "weight");
+        parameters.push_back(BiomeParameter {value, weight});
+        lua::pop(L);
+    }
+    lua::pop(L);
+
     BlocksLayers groundLayers;
     BlocksLayers seaLayers;
     try {
@@ -124,7 +140,11 @@ static inline Biome load_biome(
         throw std::runtime_error("biome "+name+": "+err.what());
     }
     lua::pop(L);
-    return Biome {name, std::move(groundLayers), std::move(seaLayers)};
+    return Biome {
+        name,
+        std::move(parameters),
+        std::move(groundLayers),
+        std::move(seaLayers)};
 }
 
 std::unique_ptr<GeneratorScript> scripting::load_generator(
@@ -141,7 +161,7 @@ std::unique_ptr<GeneratorScript> scripting::load_generator(
     uint biomeParameters = lua::get_integer_field(L, "biome_parameters", 0, 0, 16);
     uint seaLevel = lua::get_integer_field(L, "sea_level", 0, 0, CHUNK_H);
     lua::requirefield(L, "biome");
-    Biome biome = load_biome(L, "default", -1);
+    Biome biome = load_biome(L, "default", biomeParameters, -1);
     lua::pop(L);
 
     lua::pop(L);

src/world/generator/GeneratorDef.hpp

@@ -33,8 +33,17 @@ struct BlocksLayers {
     uint lastLayersHeight;
 };
 
+struct BiomeParameter {
+    /// @brief Central parameter value for the biome
+    float origin;
+    /// @brief Parameter score multiplier 
+    /// (the higher the value, the greater the chance of biome choosing)
+    float weight;
+};
+
 struct Biome {
     std::string name;
+    std::vector<BiomeParameter> parameters;
     BlocksLayers groundLayers;
     BlocksLayers seaLayers;
 };
@@ -67,6 +76,7 @@ public:
 
 /// @brief Generator information
 struct GeneratorDef {
+    /// @brief Generator full name - packid:name
     std::string name;
     std::unique_ptr<GeneratorScript> script;