#5 - fixed interpolation & rollback

modules/server/src/ZoneServer.cpp

@@ -62,6 +62,9 @@ void ZoneServer::player_update_handler(SessionId session_id, mmo::PlayerMoveMess
     if (it == m_session_zone.end()) return;
 
     if (auto* session = m_player_session_registry->session(session_id)) {
+        if(session->last_received_frame >= message.frame_idx()) {
+            return;
+        }
         session->last_received_frame = message.frame_idx();
     }
 
@@ -141,7 +144,7 @@ void ZoneServer::run() {
                 }
             }
 
-            m_replicator->replicate(zone->registry(), zone->interest());
+            m_replicator->replicate(frame_idx, zone->registry(), zone->interest());
         }
 
         m_network_receiver->update();

modules/server/src/replication/StateReplicator.hpp

@@ -29,8 +29,8 @@ class StateReplicator {
     // Per-client backing buffers reused every frame.
     std::vector<tw::serial::BinaryBuffer> m_frames;
 
-    // Header(16) + spawn_hdr(4) + despawn_hdr(4) + 512 entities × 16 bytes
-    static constexpr std::size_t kHeaderCapacity  = 24;
+    // Header(20) + spawn_hdr(4) + despawn_hdr(4) + 512 entities × 16 bytes
+    static constexpr std::size_t kHeaderCapacity  = 28;
     static constexpr std::size_t kInitialCapacity = kHeaderCapacity + 512 * 16;
 
 public:
@@ -46,6 +46,7 @@ public:
      * Replicates the current world state for one zone to its connected clients.
      */
     void replicate(
+            uint32_t frame_idx,
             const entt::registry& registry,
             const im::InterestSystem<Backend>* interest_manager
     ) {
@@ -88,7 +89,8 @@ public:
 
                 m_frames[i].reserve(needed);
                 writers[i].reset();
-                writers[i].begin(session->last_received_frame, Message<mmo::WorldStateMessage>::value);
+                writers[i].begin(session->last_received_frame, frame_idx,
+                    Message<mmo::WorldStateMessage>::value);
                 writers[i].write_spawns(state->spawn());
                 writers[i].write_despawns(state->despawn());