Save an initial state at t=0 on the client, to make sure they

can always rewind (e.g. in case that an event from another client
arrives before a state from the server).

src/modes/world_status.cpp

@@ -302,6 +302,14 @@ void WorldStatus::updateTime(int ticks)
             {
                 // set phase is over, go to the next one
                 m_phase = GO_PHASE;
+                // Save one initial state on a client, in case that an event
+                // is received from a client (trieggering a rollback) before
+                // a state from the server has been received.
+                if (NetworkConfig::get()->isClient())
+                {
+                    RewindManager::get()->saveLocalState();
+                    // FIXME TODO: save state in rewind queue!
+                }
                 if (m_play_ready_set_go_sounds)
                 {
                     m_start_sound->play();

src/network/protocols/game_protocol.cpp

@@ -245,18 +245,22 @@ void GameProtocol::handleAdjustTime(Event *event)
 // ----------------------------------------------------------------------------
 /** Called by the server before assembling a new message containing the full
  *  state of the race to be sent to a client.
- * \param allow_local_save If set it allows a state to be saved on a client.
+ * \param local_save If set it allows a state to be saved on a client.
  *        This only happens at the very first time step to ensure each client
  *        has a state in case it receives an event before a server state.
  */
-void GameProtocol::startNewState(bool allow_local_save)
+void GameProtocol::startNewState(bool local_save)
 {
-    assert(allow_local_save || NetworkConfig::get()->isServer());
+    assert(local_save || NetworkConfig::get()->isServer());
 
     m_data_to_send->clear();
-    m_data_to_send->addUInt8(GP_STATE).addUInt32(World::getWorld()->getTimeTicks());
-    Log::info("GameProtocol", "Starting new state at %d.",
-              World::getWorld()->getTimeTicks());
+    // Local saves don't neet this info, they pass time directly to the
+    // RewindInfo in RewindManager::saveLocalState.
+    if (!local_save)
+    {
+        m_data_to_send->addUInt8(GP_STATE)
+                       .addUInt32(World::getWorld()->getTimeTicks());
+    }
 }   // startNewState
 
 // ----------------------------------------------------------------------------
@@ -264,9 +268,8 @@ void GameProtocol::startNewState(bool allow_local_save)
  *  is copied, so the data can be freed after this call/.
  *  \param buffer Adds the data in the buffer to the current state.
  */
-void GameProtocol::addState(bool allow_local_save, BareNetworkString *buffer)
+void GameProtocol::addState(BareNetworkString *buffer)
 {
-    assert(allow_local_save || NetworkConfig::get()->isServer());
     m_data_to_send->addUInt16(buffer->size());
     (*m_data_to_send) += *buffer;
 }   // addState

src/network/protocols/game_protocol.hpp

@@ -78,8 +78,8 @@ public:
 
     void controllerAction(int kart_id, PlayerAction action,
                           int value, int val_l, int val_r);
-    void startNewState(bool allow_local_save);
-    void addState(bool allow_local_save, BareNetworkString *buffer);
+    void startNewState(bool local_save);
+    void addState(BareNetworkString *buffer);
     void sendState();
     void adjustTimeForClient(STKPeer *peer, int ticks);
 
@@ -101,6 +101,9 @@ public:
     {
         return m_game_protocol.lock();
     }   // lock
+    // ------------------------------------------------------------------------
+    /** Returns the NetworkString in which a state was saved. */
+    NetworkString* getState() const { return m_data_to_send;  }
 
 };   // class GameProtocol
 

src/network/rewind_manager.cpp

@@ -172,10 +172,10 @@ void RewindManager::addNetworkState(BareNetworkString *buffer, int ticks)
  *  a client before a state from the serer).
  *  \param allow_local_save Do a local save.
  */
-void RewindManager::saveState(bool allow_local_save)
+void RewindManager::saveState(bool local_save)
 {
     PROFILER_PUSH_CPU_MARKER("RewindManager - save state", 0x20, 0x7F, 0x20);
-    GameProtocol::lock()->startNewState(allow_local_save);
+    GameProtocol::lock()->startNewState(local_save);
     AllRewinder::const_iterator rewinder;
     for (rewinder = m_all_rewinder.begin(); rewinder != m_all_rewinder.end(); ++rewinder)
     {
@@ -185,14 +185,33 @@ void RewindManager::saveState(bool allow_local_save)
         if (buffer && buffer->size() >= 0)
         {
             m_overall_state_size += buffer->size();
-            GameProtocol::lock()->addState(allow_local_save, buffer);
+            GameProtocol::lock()->addState(buffer);
         }   // size >= 0
         delete buffer;    // buffer can be freed
     }
     PROFILER_POP_CPU_MARKER();
-
 }   // saveState
 
+// ----------------------------------------------------------------------------
+/** Saves a state on the client. Used to save an initial state at t=0 for each
+ *  client in case that we receive an event from another client (which will
+ *  trigger a rewind) before a state from the server.
+ */
+void RewindManager::saveLocalState()
+{
+    int ticks = World::getWorld()->getTimeTicks();
+
+    saveState(/*local_state*/true);
+    NetworkString *state = GameProtocol::lock()->getState();
+
+    // Copy the data to a new string, making the buffer in
+    // GameProtocol availble for again.
+    BareNetworkString *bns =
+        new BareNetworkString(state->getCurrentData(),
+                              state->size()           );
+    m_rewind_queue.addLocalState(bns, /*confirmed*/true, ticks);
+}   // saveLocalState
+
 // ----------------------------------------------------------------------------
 /** Restores a given state by calling rewindToState for each available rewinder
  *  with its correct data.

src/network/rewind_manager.hpp

@@ -146,7 +146,8 @@ public:
                          BareNetworkString *buffer, int ticks);
     void addNetworkState(BareNetworkString *buffer, int ticks);
     void addNextTimeStep(int ticks, float dt);
-    void saveState(bool allow_local_save);
+    void saveState(bool local_save);
+    void saveLocalState();
     void restoreState(BareNetworkString *buffer);
     // ------------------------------------------------------------------------
     /** Adds a Rewinder to the list of all rewinders.