implement inter-chunk structure generation

res/generators/default.lua

@@ -68,10 +68,13 @@ end
 
 function place_structures(x, z, w, d, seed)
     local placements = {}
-    local px = math.random() * w
-    local py = 200;
-    local pz = math.random() * d
-    table.insert(placements, {0, {px, py, pz}})
+    local hmap = generate_heightmap(x, z, w, d, seed)
+    for i=0,math.floor(math.random()*3)+5 do
+        local px = math.random() * w
+        local pz = math.random() * d
+        local py = hmap:at(px, pz) * 256
+        table.insert(placements, {0, {px-8, py, pz-8}})
+    end
     return placements
 end
 

src/logic/scripting/lua/usertypes/lua_type_heightmap.cpp

@@ -70,6 +70,15 @@ static int l_dump(lua::State* L) {
     return 0;
 }
 
+static int l_at(lua::State* L) {
+    if (auto heightmap = touserdata<LuaHeightmap>(L, 1)) {
+        int x = lua::tointeger(L, 2);
+        int y = lua::tointeger(L, 3);
+        return lua::pushnumber(L, heightmap->getHeightmap()->get(x, y));
+    }
+    return 0;
+}
+
 template<fnl_noise_type noise_type>
 static int l_noise(lua::State* L) {
     if (auto heightmap = touserdata<LuaHeightmap>(L, 1)) {
@@ -208,6 +217,7 @@ static std::unordered_map<std::string, lua_CFunction> methods {
     {"abs", lua::wrap<l_unaryop_func<util::abs>>},
     {"resize", lua::wrap<l_resize>},
     {"crop", lua::wrap<l_crop>},
+    {"at", lua::wrap<l_at>},
 };
 
 static int l_meta_meta_call(lua::State* L) {

src/logic/scripting/scripting_world_generation.cpp

@@ -121,6 +121,7 @@ public:
 
                     lua::rawgeti(L, 2);
                     glm::ivec3 pos = lua::tovec3(L, -1);
+                    lua::pop(L);
 
                     lua::pop(L);
 

src/util/listutil.hpp

@@ -1,15 +1,20 @@
 #pragma once
 
 #include <algorithm>
-#include <queue>
 #include <string>
 #include <vector>
 
 namespace util {
     template <class T>
-    bool contains(const std::vector<T>& vec, const T& value) {
+    inline bool contains(const std::vector<T>& vec, const T& value) {
         return std::find(vec.begin(), vec.end(), value) != vec.end();
     }
 
+    template <class T>
+    inline void concat(std::vector<T>& a, const std::vector<T>& b) {
+        a.reserve(a.size() + b.size());
+        a.insert(a.end(), b.begin(), b.end());
+    }
+
     std::string to_string(const std::vector<std::string>& vec);
 }

src/world/generator/WorldGenerator.cpp

@@ -10,6 +10,7 @@
 #include "GeneratorDef.hpp"
 #include "VoxelStructure.hpp"
 #include "util/timeutil.hpp"
+#include "util/listutil.hpp"
 #include "debug/Logger.hpp"
 
 static debug::Logger logger("world-generator");
@@ -132,15 +133,49 @@ std::unique_ptr<ChunkPrototype> WorldGenerator::generatePrototype(
     return std::make_unique<ChunkPrototype>();
 }
 
+inline AABB gen_chunk_aabb(int chunkX, int chunkZ) {
+    return AABB({chunkX * CHUNK_W, 0, chunkZ * CHUNK_D}, 
+                {(chunkX + 1)*CHUNK_W, 256, (chunkZ + 1) * CHUNK_D});
+}
+
 void WorldGenerator::generateStructures(
     ChunkPrototype& prototype, int chunkX, int chunkZ
 ) {
     if (prototype.level >= ChunkPrototypeLevel::STRUCTURES) {
         return;
     }
-    prototype.structures = def.script->placeStructures(
+    util::concat(prototype.structures, def.script->placeStructures(
         {chunkX * CHUNK_W, chunkZ * CHUNK_D}, {CHUNK_W, CHUNK_D}, seed
-    );
+    ));
+    for (const auto& placement : prototype.structures) {
+        const auto& offset = placement.position;
+        if (placement.structure < 0 || placement.structure >= structures.size()) {
+            logger.error() << "invalid structure index " << placement.structure;
+            continue;
+        }
+        auto& structure = *structures[placement.structure];
+        auto position = glm::ivec3(chunkX * CHUNK_W, 0, chunkZ * CHUNK_D)+offset;
+        auto size = structure.getSize() + glm::ivec3(0, CHUNK_H, 0);
+        AABB aabb(position, position + size);
+        for (int lcz = -1; lcz <= 1; lcz++) {
+            for (int lcx = -1; lcx <= 1; lcx++) {
+                if (lcx == 0 && lcz == 0) {
+                    continue;
+                }
+                auto& otherPrototype = requirePrototype(
+                    chunkX + lcx, chunkZ + lcz
+                );
+                auto chunkAABB = gen_chunk_aabb(chunkX + lcx, chunkZ + lcz);
+                if (chunkAABB.intersect(aabb)) {
+                    otherPrototype.structures.emplace_back(
+                        placement.structure, 
+                        placement.position - 
+                            glm::ivec3(lcx * CHUNK_W, 0, lcz * CHUNK_D)
+                    );
+                }
+            }
+        }
+    }
     prototype.level = ChunkPrototypeLevel::STRUCTURES;
 }
 
@@ -224,6 +259,7 @@ void WorldGenerator::generate(voxel* voxels, int chunkX, int chunkZ) {
     for (const auto& placement : prototype.structures) {
         if (placement.structure < 0 || placement.structure >= structures.size()) {
             logger.error() << "invalid structure index " << placement.structure;
+            continue;
         }
         auto& structure = *structures[placement.structure];
         auto& structVoxels = structure.getRuntimeVoxels();
@@ -244,8 +280,11 @@ void WorldGenerator::generate(voxel* voxels, int chunkX, int chunkZ) {
                     if (sx < 0 || sx >= CHUNK_W) {
                         continue;
                     }
-                    voxels[vox_index(sx, sy, sz)] = 
+                    const auto& structVoxel = 
                         structVoxels[vox_index(x, y, z, size.x, size.z)];
+                    if (structVoxel.id) {
+                        voxels[vox_index(sx, sy, sz)] = structVoxel;
+                    }
                 }
             }
         }