From 107c6a7382b0b1fa28869ce3ded4d622576ecc2a Mon Sep 17 00:00:00 2001
From: Ritchie Cunningham <ritchie@ritchiecunningham.co.uk>
Date: Wed, 17 Sep 2025 20:07:02 +0100
Subject: [PATCH] [Add] Dynamic world chunk loading.

---
 srv/game/game.h                    |  4 +++-
 srv/game/game_chunk_management.cpp | 22 ++++++++++++++++++++++
 srv/game/game_send_chunks.cpp      |  8 ++++----
 srv/game/player.cpp                |  4 +++-
 srv/game/player.h                  |  7 +++++++
 srv/main.cpp                       |  5 +++--
 6 files changed, 42 insertions(+), 8 deletions(-)
 create mode 100644 srv/game/game_chunk_management.cpp

diff --git a/srv/game/game.h b/srv/game/game.h
index 0c5340e..0c88a00 100644
--- a/srv/game/game.h
+++ b/srv/game/game.h
@@ -12,7 +12,7 @@ public:
   Player* add_player(BettolaLib::Network::TCPSocket* socket);
   void remove_player(unsigned int player_id);
 
-  void send_initial_chunks(Player* player);
+  void update_player_chunks(void);
 
   void process_udp_message(const char* buffer, size_t size, const sockaddr_in& from_addr);
   void broadcast_game_state(BettolaLib::Network::UDPSocket& udp_socket);
@@ -21,6 +21,8 @@ public:
   Player* get_player_by_id(unsigned int id);
 
 private:
+  void _send_chunks_around(Player* player, int chunk_x, int chunk_z);
+
   std::vector<Player*> _players;
   World _world;
 };
diff --git a/srv/game/game_chunk_management.cpp b/srv/game/game_chunk_management.cpp
new file mode 100644
index 0000000..e34125e
--- /dev/null
+++ b/srv/game/game_chunk_management.cpp
@@ -0,0 +1,22 @@
+#include <cmath>
+#include "game.h"
+#include "bettola/game/chunk.h"
+
+void Game::update_player_chunks(void) {
+  const int chunk_width   = BettolaLib::Game::CHUNK_WIDTH   - 1;
+  const int chunk_height  = BettolaLib::Game::CHUNK_HEIGHT  - 1;
+
+  for(Player* player : _players)  {
+    const auto& pos = player->get_position();
+
+    /* Calculate player's current chunk coords. */
+    int chunk_x = floor(pos.x / chunk_width);
+    int chunk_z = floor(pos.z / chunk_height);
+
+    /* If they have moved into a new chunk, send them the new surrounding chunks. */
+    if(chunk_z != player->get_chunk_x() || chunk_z != player->get_chunk_z()) {
+      player->set_chunk_pos(chunk_x, chunk_z);
+      _send_chunks_around(player, chunk_x, chunk_z);
+    }
+  }
+}
diff --git a/srv/game/game_send_chunks.cpp b/srv/game/game_send_chunks.cpp
index bee1e47..8ddf370 100644
--- a/srv/game/game_send_chunks.cpp
+++ b/srv/game/game_send_chunks.cpp
@@ -5,14 +5,14 @@
 #include "bettola/network/message.h"
 #include "player.h"
 
-void Game::send_initial_chunks(Player* player) {
+void Game::_send_chunks_around(Player* player, int center_x, int center_z) {
   BettolaLib::Network::MessageHeader header;
   header.type = BettolaLib::Network::MessageType::ChunkData;
   header.size = sizeof(BettolaLib::Network::ChunkMessage);
 
-  /* Send a 3x3 grid of chunks around the origin. */
-  for(int x = -1; x <=1; ++x) {
-    for(int z = -1; z <= 1; ++z) {
+  /* Send a 3x3 grid of chunks around the player's current chunk. */
+  for(int x = center_x; x <= center_x+1; ++x) {
+    for(int z = center_z-1; z <= center_z+1; ++z) {
       BettolaLib::Game::Chunk& chunk = _world.get_chunk(x, z);
 
       BettolaLib::Network::ChunkMessage msg;
diff --git a/srv/game/player.cpp b/srv/game/player.cpp
index d0f9f3f..b914f9d 100644
--- a/srv/game/player.cpp
+++ b/srv/game/player.cpp
@@ -8,7 +8,9 @@
 Player::Player(BettolaLib::Network::TCPSocket* socket) :
       PlayerBase(),
       _socket(socket),
-      _has_udp_addr(false) {
+      _has_udp_addr(false),
+      _chunk_x(INT_MAX),
+      _chunk_z(INT_MAX) {
 
   _last_processed_sequence = 0;
   memset(&_udp_addr, 0, sizeof(_udp_addr));
diff --git a/srv/game/player.h b/srv/game/player.h
index d34734f..50d62a3 100644
--- a/srv/game/player.h
+++ b/srv/game/player.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <limits.h>
 #include <netinet/in.h>
 
 #include "bettola/network/tcpsocket.h"
@@ -19,9 +20,15 @@ public:
   void set_last_processed_sequence(unsigned int sequence) { _last_processed_sequence = sequence; }
   unsigned int get_last_processed_sequence(void) const { return _last_processed_sequence; }
 
+  int get_chunk_x(void) const      { return _chunk_x; }
+  int get_chunk_z(void) const      { return _chunk_z; }
+  void set_chunk_pos(int x, int z) { _chunk_x = x; _chunk_z = z; }
+
 private:
   BettolaLib::Network::TCPSocket* _socket;
   sockaddr_in _udp_addr;
   bool _has_udp_addr;
   unsigned int _last_processed_sequence;
+  int _chunk_x;
+  int _chunk_z;
 };
diff --git a/srv/main.cpp b/srv/main.cpp
index 0b6cc52..8b510af 100644
--- a/srv/main.cpp
+++ b/srv/main.cpp
@@ -112,8 +112,6 @@ int main(void) {
           unsigned int id = new_player->get_id();
           client_socket->send(&id, sizeof(id));
 
-          game.send_initial_chunks(new_player);
-
           int client_flags = fcntl(client_socket->get_sockfd(), F_GETFL, 0);
           fcntl(client_socket->get_sockfd(), F_SETFL, client_flags | O_NONBLOCK);
 
@@ -165,6 +163,9 @@ int main(void) {
       }
     }
 
+    /* Update dynamic game state, like chunk loading for players. */
+    game.update_player_chunks();
+
     /* Broadcase game state. */
     game.broadcast_game_state(udp_socket);