Fix #3875

data/stk_config.xml

@@ -588,5 +588,6 @@
   <network-capabilities>
       <capabilities name="report_player"/>
       <capabilities name="color_emoji"/>
+      <capabilities name="ranking_changes"/>
   </network-capabilities>
 </config>

src/network/protocols/client_lobby.cpp

@@ -124,6 +124,7 @@ ClientLobby::~ClientLobby()
 //-----------------------------------------------------------------------------
 void ClientLobby::setup()
 {
+    m_ranking_changes.clear();
     m_spectator = false;
     m_server_send_live_load_world = false;
     m_auto_back_to_lobby_time = std::numeric_limits<uint64_t>::max();
@@ -1097,6 +1098,20 @@ void ClientLobby::raceFinished(Event* event)
         }
     }
 
+    m_ranking_changes.clear();
+    // Ranking changes from server
+    if (NetworkConfig::get()->getServerCapabilities().find("ranking_changes")
+        != NetworkConfig::get()->getServerCapabilities().end())
+    {
+        bool has_ranking_changes = (data.getUInt8() & 1) != 0;
+        if (has_ranking_changes)
+        {
+            unsigned count = data.getUInt8();
+            for (unsigned i = 0; i < count; i++)
+                m_ranking_changes.push_back(data.getFloat());
+        }
+    }
+
     // stop race protocols
     RaceEventManager::getInstance()->stop();
     ProtocolManager::lock()->findAndTerminate(PROTOCOL_GAME_EVENTS);

src/network/protocols/client_lobby.hpp

@@ -128,6 +128,8 @@ private:
 
     std::vector<LobbyPlayer> m_lobby_players;
 
+    std::vector<float> m_ranking_changes;
+
     irr::core::stringw m_total_players;
 
     void liveJoinAcknowledged(Event* event);
@@ -178,6 +180,8 @@ public:
                                       { return m_server_enabled_track_voting; }
     bool serverEnabledReportPlayer() const
                                      { return m_server_enabled_report_player; }
+    const std::vector<float>& getRankingChanges() const
+                                                  { return m_ranking_changes; }
 };
 
 #endif // CLIENT_LOBBY_HPP

src/network/protocols/server_lobby.cpp

@@ -2389,6 +2389,12 @@ void ServerLobby::checkRaceFinished()
         m_result_ns->encodeString(static_cast<LinearWorld*>(World::getWorld())
             ->getFastestLapKartName());
     }
+
+    uint8_t ranking_changes_indication = 0;
+    if (ServerConfig::m_ranked && race_manager->modeHasLaps())
+        ranking_changes_indication = 1;
+    m_result_ns->addUInt8(ranking_changes_indication);
+
     if (ServerConfig::m_ranked)
     {
         computeNewRankings();
@@ -2411,13 +2417,17 @@ void ServerLobby::computeNewRankings()
     // Would this be worth it ?
     std::vector<double> scores_change;
     std::vector<double> new_scores;
+    std::vector<double> prev_scores;
 
     unsigned player_count = race_manager->getNumPlayers();
+    m_result_ns->addUInt8((uint8_t)player_count);
     for (unsigned i = 0; i < player_count; i++)
     {
         const uint32_t id = race_manager->getKartInfo(i).getOnlineId();
-        new_scores.push_back(m_scores.at(id));
+        double prev_score = m_scores.at(id);
+        new_scores.push_back(prev_score);
         new_scores[i] += distributeBasePoints(id);
+        prev_scores.push_back(prev_score);
     }
  
     // First, update the number of ranked races
@@ -2537,6 +2547,13 @@ void ServerLobby::computeNewRankings()
         if (m_scores.at(id) > m_max_scores.at(id))
             m_max_scores.at(id) = m_scores.at(id);
     }
+
+    for (unsigned i = 0; i < player_count; i++)
+    {
+        const uint32_t id = race_manager->getKartInfo(i).getOnlineId();
+        double change = m_scores.at(id) - prev_scores[i];
+        m_result_ns->addFloat((float)change);
+    }
 }   // computeNewRankings
 
 //-----------------------------------------------------------------------------

src/states_screens/race_result_gui.cpp

@@ -735,6 +735,7 @@ void RaceResultGUI::displayCTFResults()
         int time_precision = race_manager->currentModeTimePrecision();
         bool active_gp = (race_manager->getMajorMode() == RaceManager::MAJOR_MODE_GRAND_PRIX);
 
+        auto cl = LobbyProtocol::get<ClientLobby>();
         for (unsigned int position = first_position;
         position <= race_manager->getNumberOfKarts() - sta; position++)
         {
@@ -780,6 +781,22 @@ void RaceResultGUI::displayCTFResults()
                 std::string time_string = StringUtils::timeToString(time, time_precision);
                 ri->m_finish_time_string = time_string.c_str();
             }
+            if (cl && !cl->getRankingChanges().empty())
+            {
+                unsigned kart_id = kart->getWorldKartId();
+                if (kart_id < cl->getRankingChanges().size())
+                {
+                    ri->m_finish_time_string += L" ";
+                    float ranking_change = cl->getRankingChanges()[kart_id];
+                    if (ranking_change > 0)
+                    {
+                        ri->m_finish_time_string += L"+";
+                        ri->m_finish_time_string += StringUtils::toWString(ranking_change);
+                    }
+                    else
+                        ri->m_finish_time_string += StringUtils::toWString(ranking_change);
+                }
+            }
 
             core::dimension2du rect =
                 m_font->getDimension(ri->m_kart_name.c_str());