World Management

class Level {
public:
    Dimension* dimension;
    ChunkSource* chunkSource;
    LevelData* levelData;
    shared_ptr<LevelStorage> levelStorage;
    
    bool isClientSide;
    int difficulty;
    static const int maxBuildHeight = 128;
    static const int minBuildHeight = 0;
};

class LevelChunk {
public:
    int x, z;                    // Chunk coordinates
    byte* tiles;                 // Block IDs
    NibbleArray* data;          // Block metadata
    NibbleArray* skyLight;      // Sky light levels
    NibbleArray* blockLight;    // Block light levels
    int* heightmap;             // Height map
};

LevelChunk* Level::getChunk(int x, int z) {
    return this->chunkSource->getChunk(x, z);
}

bool Level::hasChunk(int x, int z) {
    return this->chunkSource->hasChunk(x, z);
}

class ServerChunkCache : public ChunkSource {
    ChunkStorage* storage;
    ChunkSource* generator;
    map<int, LevelChunk*> chunks;
};

class MultiPlayerChunkCache : public ChunkSource {
    MultiPlayerLevel* level;
    LevelChunk* emptyChunk;
    map<int, LevelChunk*> chunkMap;
};

Dimension* Dimension::getNew(int id) {
    switch(id) {
        case 0:  return new NormalDimension();     // Overworld
        case -1: return new HellDimension();       // Nether
        case 1:  return new TheEndDimension();     // The End
    }
}

ServerLevelArray levels = ServerLevelArray(3);

for (int i = 0; i < 3; i++) {
    int dimension = (i == 1) ? -1 : (i == 2) ? 1 : 0;
    
    if (i == 0) {
        levels[i] = new ServerLevel(...);
    } else {
        levels[i] = new DerivedServerLevel(...);
    }
}

int r = 196;  // Radius in blocks

Pos* spawnPos = level->getSharedSpawnPos();

for (int x = -r; x <= r; x += 16) {
    for (int z = -r; z <= r; z += 16) {
        level->cache->create(
            (spawnPos->x + x) >> 4, 
            (spawnPos->z + z) >> 4,
            true  // Enable post-processing
        );
    }
}

m_postUpdateThread = new C4JThread(
    runPostUpdate, 
    this, 
    "Post processing",
    256*1024  // Stack size
);

m_postUpdateThread->SetProcessor(CPU_CORE_POST_PROCESSING);
m_postUpdateThread->SetPriority(THREAD_PRIORITY_ABOVE_NORMAL);

class LevelData {
public:
    long seed;                  // World seed
    long time;                  // World time
    Pos spawnPos;              // Spawn location
    bool raining;              // Weather state
    int rainTime;
    bool thundering;
    int thunderTime;
    GameType gameType;         // Survival/Creative
    bool hardcore;
    bool mapFeatures;          // Structures enabled
};

void MinecraftServer::saveAllChunks() {
    for (int i = 0; i < levels.length; i++) {
        ServerLevel* level = levels[levels.length - 1 - i];
        
        level->save(true, progressRenderer);
        
        if (i == levels.length - 1) {
            level->closeLevelStorage();
        }
    }
}

void LevelChunk::compressLighting() {
    // Compress sky and block light
}

void LevelChunk::compressBlocks() {
    // Compress block data
}

void LevelChunk::compressData() {
    // Compress metadata
}

static const int MAX_LEVEL_SIZE = dimension->getXZSize() * 16 / 2;

if (x < -MAX_LEVEL_SIZE || x >= MAX_LEVEL_SIZE) {
    return 0;  // Out of bounds
}
if (z < -MAX_LEVEL_SIZE || z >= MAX_LEVEL_SIZE) {
    return 0;  // Out of bounds
}

void Level::initCache(lightCache_t* cache) {
    cachewritten = false;
    if (cache == NULL) return;
    XMemSet128(cache, 0, 16*16*16*sizeof(lightCache_t));
}

void Level::flushCache(lightCache_t* cache, __uint64 cacheUse, 
                       LightLayer::variety layer) {
    // Write cached lighting updates
}

for (int i = 0; i < levels.length; i++) {
    ServerLevel* level = levels[i];
    
    level->difficulty = options->difficulty;
    level->setSpawnSettings(difficulty > 0, animals);
    
    if (tickCount % 20 == 0) {
        // Broadcast time update
        players->broadcastAll(
            new SetTimePacket(level->getTime())
        );
    }
    
    level->tick();       // Physics, entities
    level->tickPending(); // Scheduled updates
}

void MultiPlayerLevel::setChunkVisible(int x, int z, bool visible) {
    if (visible) {
        chunkCache->create(x, z);
    } else {
        chunkCache->drop(x, z);
        setTilesDirty(x*16, 0, z*16, x*16+15, maxBuildHeight, z*16+15);
    }
}