add generator layers

res/generators/default.lua

@@ -1,3 +1,10 @@
+layers = {
+    {block="base:grass_block", height=1},
+    {block="base:dirt", height=1},
+    {block="base:stone", height=-1},
+    {block="base:bazalt", height=1},
+}
+
 function generate_heightmap(x, y, w, h)
     local umap = Heightmap(w, h)
     local vmap = Heightmap(w, h)

src/content/ContentBuilder.cpp

@@ -88,5 +88,9 @@ std::unique_ptr<Content> ContentBuilder::build() {
         def->rt.placingBlock = content->blocks.require(def->placingBlock).rt.id;
     }
 
+    for (auto& [name, def] : content->generators.getDefs()) {
+        def->script->prepare(content.get());
+    }
+
     return content;
 }

src/content/ContentLoader.cpp

@@ -473,7 +473,11 @@ void ContentLoader::load() {
 
             auto& def = builder.generators.create(full);
 
-            loadGenerator(def, full, name);
+            try {
+                loadGenerator(def, full, name);
+            } catch (const std::runtime_error& err) {
+                throw std::runtime_error("generator '"+full+"': "+err.what());
+            }
         }
     }
 

src/logic/scripting/lua/lua_util.hpp

@@ -496,17 +496,26 @@ namespace lua {
     }
 
     int pushvalue(lua::State*, const dynamic::Value& value);
+
+    [[nodiscard]]
     dynamic::Value tovalue(lua::State*, int idx);
 
     inline bool getfield(lua::State* L, const std::string& name, int idx = -1) {
         lua_getfield(L, idx, name.c_str());
-        if (isnil(L, -1)) {
+        if (isnil(L, idx)) {
             pop(L);
             return false;
         }
         return true;
     }
 
+    inline int requirefield(lua::State* L, const std::string& name, int idx = -1) {
+        if (getfield(L, name, idx)) {
+            return 1;
+        }
+        throw std::runtime_error("object has no member '"+name+"'");
+    }
+
     inline bool hasfield(lua::State* L, const std::string& name, int idx = -1) {
         lua_getfield(L, idx, name.c_str());
         if (isnil(L, -1)) {

src/logic/scripting/scripting.cpp

@@ -686,8 +686,11 @@ void scripting::load_entity_component(
 
 class LuaGeneratorScript : public GeneratorScript {
     scriptenv env;
+    std::vector<BlocksLayer> layers;
+    uint lastLayersHeight;
 public:
-    LuaGeneratorScript(scriptenv env) : env(std::move(env)) {}
+    LuaGeneratorScript(scriptenv env, std::vector<BlocksLayer> layers, uint lastLayersHeight)
+    : env(std::move(env)), layers(std::move(layers)), lastLayersHeight(lastLayersHeight) {}
 
     std::shared_ptr<Heightmap> generateHeightmap(
         const glm::ivec2& offset, const glm::ivec2& size
@@ -706,6 +709,20 @@ public:
         lua::pop(L);
         return std::make_shared<Heightmap>(size.x, size.y);
     }
+
+    void prepare(const Content* content) override {
+        for (auto& layer : layers) {
+            layer.rt.id = content->blocks.require(layer.block).rt.id;
+        }
+    }
+
+    const std::vector<BlocksLayer>& getLayers() const override {
+        return layers;
+    }
+
+    uint getLastLayersHeight() const override {
+        return lastLayersHeight;
+    }
 };
 
 std::unique_ptr<GeneratorScript> scripting::load_generator(
@@ -713,7 +730,46 @@ std::unique_ptr<GeneratorScript> scripting::load_generator(
 ) {
     auto env = create_environment();
     load_script(*env, "generator", file);
-    return std::make_unique<LuaGeneratorScript>(std::move(env));
+
+    auto L = lua::get_main_thread();
+    lua::pushenv(L, *env);
+
+    uint lastLayersHeight = 0;
+    bool hasResizeableLayer = false;
+
+    std::vector<BlocksLayer> layers;
+    if (lua::getfield(L, "layers")) {
+        int len = lua::objlen(L, -1);
+        for (int i = 1; i <= len; i++) {
+            try {
+                lua::rawgeti(L, i);
+                lua::requirefield(L, "block");
+                auto name = lua::require_string(L, -1);
+                lua::pop(L);
+                lua::requirefield(L, "height");
+                int height = lua::tointeger(L, -1);
+                lua::pop(L, 2);
+
+                if (hasResizeableLayer) {
+                    lastLayersHeight += height;
+                }
+                if (height == -1) {
+                    if (hasResizeableLayer) {
+                        throw std::runtime_error("only one resizeable layer allowed");
+                    }
+                    hasResizeableLayer = true;
+                }
+                layers.push_back(BlocksLayer {name, height, {}});
+            } catch (const std::runtime_error& err) {
+                lua::pop(L, 2);
+                throw std::runtime_error(
+                    "layer #"+std::to_string(i)+": "+err.what());
+            }
+        }
+        lua::pop(L);
+    }
+    lua::pop(L);
+    return std::make_unique<LuaGeneratorScript>(std::move(env), std::move(layers), lastLayersHeight);
 }
 
 void scripting::load_world_script(

src/world/generator/GeneratorDef.hpp

@@ -6,12 +6,30 @@
 #include "typedefs.hpp"
 #include "maths/Heightmap.hpp"
 
+class Content;
+
+struct BlocksLayer {
+    std::string block;
+    int height;
+
+    struct {
+        blockid_t id;
+    } rt;
+};
+
 class GeneratorScript {
 public:
     virtual ~GeneratorScript() = default;
 
     virtual std::shared_ptr<Heightmap> generateHeightmap(
         const glm::ivec2& offset, const glm::ivec2& size) = 0;
+
+    virtual const std::vector<BlocksLayer>& getLayers() const = 0;
+
+    /// @brief Total height of all layers after resizeable one
+    virtual uint getLastLayersHeight() const = 0;
+
+    virtual void prepare(const Content* content) = 0;
 };
 
 struct GeneratorDef {

src/world/generator/WorldGenerator.cpp

@@ -1,5 +1,7 @@
 #include "WorldGenerator.hpp"
 
+#include <cstring>
+
 #include "content/Content.hpp"
 #include "voxels/Block.hpp"
 #include "voxels/Chunk.hpp"
@@ -14,21 +16,32 @@ WorldGenerator::WorldGenerator(
 
 #include "util/timeutil.hpp"
 void WorldGenerator::generate(voxel* voxels, int chunkX, int chunkZ, int seed) {
-    timeutil::ScopeLogTimer log(555);
     auto heightmap = def.script->generateHeightmap(
         {chunkX*CHUNK_W, chunkZ*CHUNK_D}, {CHUNK_W, CHUNK_D}
     );
-    auto& baseStone = content->blocks.require("base:stone");
-    auto& baseWater = content->blocks.require("base:water");
+    timeutil::ScopeLogTimer log(555);
+    auto values = heightmap->getValues();
+    const auto& layers = def.script->getLayers();
+    uint lastLayersHeight = def.script->getLastLayersHeight();
+    auto baseWater = content->blocks.require("base:water").rt.id;
+
+    std::memset(voxels, 0, sizeof(voxel) * CHUNK_VOL);
+
     for (uint z = 0; z < CHUNK_D; z++) {
         for (uint x = 0; x < CHUNK_W; x++) {
-            auto height = heightmap->getValues()[z * CHUNK_W + x] * 255 + 10;
-            for (uint y = 0; y < CHUNK_H; y++) {
-                voxels[vox_index(x, y, z)].state = {};
-                if (y > height) {
-                    voxels[vox_index(x, y, z)].id = y <= 64 ? baseWater.rt.id : 0;
-                } else {
-                    voxels[vox_index(x, y, z)].id = baseStone.rt.id;
+            int height = values[z * CHUNK_W + x] * 255 + 10;
+            for (uint y = height+1; y < 64; y++) {
+                voxels[vox_index(x, y, z)].id = baseWater;
+            }
+
+            uint y = height;
+            for (const auto& layer : layers) {
+                uint layerHeight = layer.height;
+                if (layerHeight == -1) {
+                    layerHeight = y - lastLayersHeight + 1;
+                }
+                for (uint i = 0; i < layerHeight; i++, y--) {
+                    voxels[vox_index(x, y, z)].id = layer.rt.id;
                 }
             }
         }