implement BB EXP share

src/HTTPServer.cc

@@ -579,6 +579,7 @@ JSON HTTPServer::generate_lobby_json_st(shared_ptr<const Lobby> l, shared_ptr<co
       ret.emplace("Mode", name_for_mode(l->mode));
       ret.emplace("Difficulty", name_for_difficulty(l->difficulty));
       ret.emplace("BaseEXPMultiplier", l->base_exp_multiplier);
+      ret.emplace("EXPShareMultiplier", l->exp_share_multiplier);
       ret.emplace("AllowedDropModes", l->allowed_drop_modes);
       switch (l->drop_mode) {
         case Lobby::DropMode::DISABLED:

src/Lobby.cc

@@ -149,6 +149,7 @@ Lobby::Lobby(shared_ptr<ServerState> s, uint32_t id, bool is_game)
       mode(GameMode::NORMAL),
       difficulty(0),
       base_exp_multiplier(1),
+      exp_share_multiplier(0.5),
       challenge_exp_multiplier(1.0f),
       random_seed(random_object<uint32_t>()),
       drop_mode(DropMode::CLIENT),

src/Lobby.hh

@@ -123,6 +123,7 @@ struct Lobby : public std::enable_shared_from_this<Lobby> {
   GameMode mode;
   uint8_t difficulty; // 0-3
   uint16_t base_exp_multiplier;
+  float exp_share_multiplier;
   float challenge_exp_multiplier;
   std::string password;
   std::string name;

src/Map.cc

@@ -678,10 +678,10 @@ Map::Enemy::Enemy(
       wave_number(wave_number),
       type(type),
       floor(floor),
-      state_flags(0) {}
+      server_flags(0) {}
 
 string Map::Enemy::str() const {
-  return string_printf("[Map::Enemy E-%hX source %zX %s%s floor=%02hhX section=%04hX wave_number=%04hX flags=%02hhX]",
+  return string_printf("[Map::Enemy E-%hX source %zX %s%s floor=%02hhX section=%04hX wave_number=%04hX server_flags=%02hhX]",
       this->enemy_id,
       this->source_index,
       name_for_enum(this->type),
@@ -689,7 +689,7 @@ string Map::Enemy::str() const {
       this->floor,
       this->section,
       this->wave_number,
-      this->state_flags);
+      this->server_flags);
 }
 
 string Map::Event::str() const {

src/Map.hh

@@ -233,11 +233,11 @@ struct Map {
 
   struct Enemy {
     enum Flag {
-      EXP_REQUESTED_BY_PLAYER0 = 0x01,
-      EXP_REQUESTED_BY_PLAYER1 = 0x02,
-      EXP_REQUESTED_BY_PLAYER2 = 0x04,
-      EXP_REQUESTED_BY_PLAYER3 = 0x08,
-      ITEM_DROPPED = 0x10,
+      LAST_HIT_MASK = 0x03,
+      EXP_GIVEN = 0x04,
+      ITEM_DROPPED = 0x08,
+      ALL_HITS_MASK_FIRST = 0x10,
+      ALL_HITS_MASK = 0xF0,
     };
     size_t source_index;
     size_t set_index;
@@ -248,7 +248,7 @@ struct Map {
     uint16_t wave_number;
     EnemyType type;
     uint8_t floor;
-    uint8_t state_flags;
+    uint8_t server_flags;
 
     Enemy(
         uint16_t enemy_id,
@@ -260,6 +260,16 @@ struct Map {
         EnemyType type);
 
     std::string str() const;
+
+    inline bool ever_hit_by_client_id(uint8_t client_id) const {
+      return this->server_flags & (Flag::ALL_HITS_MASK_FIRST << client_id);
+    }
+    inline bool last_hit_by_client_id(uint8_t client_id) const {
+      return (this->server_flags & Flag::LAST_HIT_MASK) == client_id;
+    }
+    inline void set_last_hit_by_client_id(uint8_t client_id) {
+      this->server_flags = (this->server_flags & (~Flag::LAST_HIT_MASK)) | (Flag::ALL_HITS_MASK_FIRST << client_id) | (client_id & 3);
+    }
   };
 
   struct Event {

src/ReceiveCommands.cc

@@ -4257,9 +4257,8 @@ shared_ptr<Lobby> create_game_generic(
     game->battle_player = battle_player;
     battle_player->set_lobby(game);
   }
-  if (game->base_version == Version::BB_V4) {
-    game->base_exp_multiplier = s->bb_global_exp_multiplier;
-  }
+  game->base_exp_multiplier = s->bb_global_exp_multiplier;
+  game->exp_share_multiplier = s->exp_share_multiplier;
 
   const unordered_map<uint16_t, IntegralExpression>* quest_flag_rewrites;
   switch (game->base_version) {

src/ReceiveSubcommands.cc

@@ -2625,11 +2625,11 @@ DropReconcileResult reconcile_drop_request_with_map(
       }
     }
     if (map_enemy) {
-      if (map_enemy->state_flags & Map::Enemy::Flag::ITEM_DROPPED) {
+      if (map_enemy->server_flags & Map::Enemy::Flag::ITEM_DROPPED) {
         log.info("Drop check has already occurred for E-%04hX; skipping it", map_enemy->enemy_id);
         res.should_drop = false;
       } else {
-        map_enemy->state_flags |= Map::Enemy::Flag::ITEM_DROPPED;
+        map_enemy->server_flags |= Map::Enemy::Flag::ITEM_DROPPED;
       }
     }
   }
@@ -3190,6 +3190,7 @@ static void on_update_enemy_state(shared_ptr<Client> c, uint8_t command, uint8_t
     auto& enemy = l->map->enemies[cmd.enemy_index];
     enemy.game_flags = is_big_endian(c->version()) ? bswap32(cmd.flags) : cmd.flags.load();
     enemy.total_damage = cmd.total_damage;
+    enemy.set_last_hit_by_client_id(c->lobby_client_id);
     l->log.info("E-%hX updated to damage=%hu game_flags=%08" PRIX32, cmd.enemy_index.load(), enemy.total_damage, enemy.game_flags);
   }
 
@@ -3397,10 +3398,6 @@ static void on_enemy_exp_request_bb(shared_ptr<Client> c, uint8_t, uint8_t, void
   auto s = c->require_server_state();
   auto l = c->require_lobby();
 
-  if (l->base_version != Version::BB_V4) {
-    throw runtime_error("BB-only command sent in non-BB game");
-  }
-
   const auto& cmd = check_size_t<G_EnemyEXPRequest_BB_6xC8>(data, size);
 
   if (!l->is_game()) {
@@ -3421,66 +3418,85 @@ static void on_enemy_exp_request_bb(shared_ptr<Client> c, uint8_t, uint8_t, void
   string e_str = e.str();
   c->log.info("EXP requested for E-%hX => %s", cmd.enemy_index.load(), e_str.c_str());
 
-  uint8_t state_flag = Map::Enemy::Flag::EXP_REQUESTED_BY_PLAYER0 << c->lobby_client_id;
-  if (e.state_flags & state_flag) {
+  // If the requesting player never hit this enemy, they are probably cheating;
+  // ignore the command. Also, each player sends a 6xC8 if they ever hit the
+  // enemy; we only react to the first 6xC8 for each enemy (and give all
+  // relevant players EXP then, if they deserve it).
+  if (!e.ever_hit_by_client_id(c->lobby_client_id) || (e.server_flags & Map::Enemy::Flag::EXP_GIVEN)) {
+    return;
+  }
+  e.server_flags |= Map::Enemy::Flag::EXP_GIVEN;
+
+  double base_exp = 0.0;
+  try {
+    const auto& bp_table = s->battle_params->get_table(l->mode == GameMode::SOLO, l->episode);
+    uint32_t bp_index = battle_param_index_for_enemy_type(l->episode, e.type);
+    base_exp = bp_table.stats[l->difficulty][bp_index].experience;
+  } catch (const exception& e) {
     if (c->config.check_flag(Client::Flag::DEBUG_ENABLED)) {
-      send_text_message_printf(c, "$C5E-%hX __CHECKED__", cmd.enemy_index.load());
+      send_text_message_printf(c, "$C5E-%hX __MISSING__\n%s", cmd.enemy_index.load(), e.what());
+    } else {
+      send_text_message_printf(c, "$C4Unknown enemy killed:\n%s", e.what());
+    }
+  }
+
+  for (size_t client_id = 0; client_id < 4; client_id++) {
+    auto lc = l->clients[client_id];
+    if (!lc) {
+      continue;
     }
 
-  } else {
-    e.state_flags |= state_flag;
-
-    double experience = 0.0;
-    try {
-      const auto& bp_table = s->battle_params->get_table(l->mode == GameMode::SOLO, l->episode);
-      uint32_t bp_index = battle_param_index_for_enemy_type(l->episode, e.type);
-      experience = bp_table.stats[l->difficulty][bp_index].experience;
-    } catch (const exception& e) {
-      if (c->config.check_flag(Client::Flag::DEBUG_ENABLED)) {
-        send_text_message_printf(c, "$C5E-%hX __MISSING__\n%s", cmd.enemy_index.load(), e.what());
+    if (base_exp != 0.0) {
+      // If this player killed the enemy, they get full EXP; if they tagged the
+      // enemy, they get 80% EXP; if auto EXP share is enabled and they are
+      // close enough to the monster, they get a smaller share; if none of these
+      // situations apply, they get no EXP.
+      double rate_factor;
+      if (e.last_hit_by_client_id(client_id)) {
+        rate_factor = max<double>(1.0, l->exp_share_multiplier);
+      } else if (e.ever_hit_by_client_id(client_id)) {
+        rate_factor = max<double>(0.8, l->exp_share_multiplier);
+      } else if (lc->floor == e.floor) {
+        rate_factor = l->exp_share_multiplier;
       } else {
-        send_text_message_printf(c, "$C4Unknown enemy killed:\n%s", e.what());
+        rate_factor = 0.0;
       }
-    }
 
-    if (experience != 0.0) {
-      if (c->floor != e.floor) {
-        if (c->config.check_flag(Client::Flag::DEBUG_ENABLED)) {
-          send_text_message_printf(c, "$C5E-%hX %s\n$C4FLOOR Y:%02" PRIX32 " E:%02hhX",
-              cmd.enemy_index.load(), name_for_enum(e.type), c->floor, e.floor);
-        }
-      } else {
+      if (rate_factor > 0.0) {
         // In PSOBB, Sega decided to add a 30% EXP boost for Episode 2. They could
         // have done something reasonable, like edit the BattleParamEntry files so
         // the monsters would all give more EXP, but they did something far lazier
         // instead: they just stuck an if statement in the client's EXP request
         // function. We, unfortunately, have to do the same here.
         bool is_ep2 = (l->episode == Episode::EP2);
-        uint32_t player_exp = experience *
-            (cmd.is_killer ? 1.0 : 0.8) *
+        uint32_t player_exp = base_exp *
+            rate_factor *
             l->base_exp_multiplier *
             l->challenge_exp_multiplier *
             (is_ep2 ? 1.3 : 1.0);
-        if (c->config.check_flag(Client::Flag::DEBUG_ENABLED)) {
+        if (lc->config.check_flag(Client::Flag::DEBUG_ENABLED)) {
           send_text_message_printf(
-              c, "$C5+%" PRIu32 " E-%hX %s",
+              lc, "$C5+%" PRIu32 " E-%hX %s",
               player_exp,
               cmd.enemy_index.load(),
               name_for_enum(e.type));
         }
-        if (c->character()->disp.stats.level < 199) {
-          add_player_exp(c, player_exp);
+        if (lc->character()->disp.stats.level < 199) {
+          add_player_exp(lc, player_exp);
         }
       }
     }
 
     // Update kill counts on unsealable items
-    auto& inventory = c->character()->inventory;
-    for (size_t z = 0; z < inventory.num_items; z++) {
-      auto& item = inventory.items[z];
-      if ((item.flags & 0x08) &&
-          s->item_parameter_table(c->version())->is_unsealable_item(item.data)) {
-        item.data.set_kill_count(item.data.get_kill_count() + 1);
+    // TODO: Do tags count too, even if the player didn't actually strike the
+    // final blow? Here we assume tags do count.
+    if (e.ever_hit_by_client_id(client_id)) {
+      auto& inventory = lc->character()->inventory;
+      for (size_t z = 0; z < inventory.num_items; z++) {
+        auto& item = inventory.items[z];
+        if ((item.flags & 0x08) && s->item_parameter_table(lc->version())->is_unsealable_item(item.data)) {
+          item.data.set_kill_count(item.data.get_kill_count() + 1);
+        }
       }
     }
   }

src/SendCommands.cc

@@ -2710,7 +2710,7 @@ void send_game_enemy_state(shared_ptr<Client> c) {
     const auto& enemy = l->map->enemies[z];
     auto& entry = entries.emplace_back();
     entry.flags = enemy.game_flags;
-    entry.item_drop_id = (enemy.state_flags & Map::Enemy::Flag::ITEM_DROPPED) ? 0xFFFF : (0xCA0 + z);
+    entry.item_drop_id = (enemy.server_flags & Map::Enemy::Flag::ITEM_DROPPED) ? 0xFFFF : (0xCA0 + z);
     entry.total_damage = enemy.total_damage;
   }
 

src/ServerState.cc

@@ -935,6 +935,7 @@ void ServerState::load_config_early() {
   }
 
   this->bb_global_exp_multiplier = this->config_json->get_int("BBGlobalEXPMultiplier", 1);
+  this->exp_share_multiplier = this->config_json->get_float("BBEXPShareMultiplier", 0.5);
   this->server_global_drop_rate_multiplier = this->config_json->get_float("ServerGlobalDropRateMultiplier", 1);
 
   set_log_levels_from_json(this->config_json->get("LogLevels", JSON::dict()));

src/ServerState.hh

@@ -200,6 +200,7 @@ struct ServerState : public std::enable_shared_from_this<ServerState> {
   QuestF960Result quest_F960_failure_results;
   std::vector<ItemData> secret_lottery_results;
   uint16_t bb_global_exp_multiplier = 1;
+  float exp_share_multiplier = 0.5;
   double server_global_drop_rate_multiplier = 1.0;
 
   std::shared_ptr<Episode3::TournamentIndex> ep3_tournament_index;

system/config.example.json

@@ -827,6 +827,20 @@
   // EXP multiplier for BB games. This must be an integer due to a client
   // limitation, and must be at least 1.
   "BBGlobalEXPMultiplier": 1,
+  // EXP share multiplier for BB games. The logic for EXP computation is:
+  // - If the player lands the killing blow on an enemy they get full EXP (or
+  //   multiplied by this value, if this value is greater than 1).
+  // - If the player tags an enemy but doesn't kill it, they get full EXP
+  //   multiplied by 80% (or multiplied by this value, if this value is greater
+  //   than 0.8). This applies even if the player is on a different floor when
+  //   the enemy dies.
+  // - If the player is on the same floor as an enemy when it is killed but
+  //   the player never attacked it, they get full EXP multiplied by this value
+  //   (50% by default).
+  // - If the player is not on the same floor as an enemy when it is killed and
+  //   never tagged it, they get no EXP.
+  // To disable EXP share in BB games, set this to zero.
+  "BBEXPShareMultiplier": 0.5,
   // Drop rate multiplier for all server drop tables. This applies to server
   // drop modes in all game versions. If you want to scale the drop rates for
   // only some versions, use the --multiply option to the convert-rare-item-set

tests/config.json

@@ -312,6 +312,7 @@
     "031000",
   ],
   "BBGlobalEXPMultiplier": 1,
+  "BBEXPShareMultiplier": 0.5,
   "ServerGlobalDropRateMultiplier": 1.0,
   "UseGameCreatorSectionID": false,