Share online membership and game setup with the server

Profile, member join/leave and building a fresh game move into the sim library,
and the packet reader and writer into protocol.h, so the server can run lobbies
exactly as clients do.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/match.cpp

@@ -1,6 +1,7 @@
 #include "match.h"
 #include "sim.h"
 #include <algorithm>
+#include <cstring>
 
 constexpr Burst FINISH_BURST = {.gravity = 200, .life = 1, .size = 3, .speed = 240, .count = 40};
 constexpr float RACE_GRACE = 15;
@@ -746,3 +747,80 @@ void Match::leaves_take(Sim& sim)
     std::fill(std::begin(isReady), std::end(isReady), false);
     sim.cues->sound_play(SOUND_FINISH);
 }
+
+// A fighter's loadout, slots and levels as a profile, to bring it back as it was (a name and colour are added by whoever
+// knows them).
+Profile profile_get(Fighter& fighter)
+{
+    Profile profile;
+    profile.weaponSlots = fighter.weaponSlots;
+    profile.trinketSlots = fighter.trinketSlots;
+    std::copy(std::begin(fighter.weaponLoadout), std::end(fighter.weaponLoadout), profile.weaponLoadout);
+    std::copy(std::begin(fighter.trinketLoadout), std::end(fighter.trinketLoadout), profile.trinketLoadout);
+    std::copy(std::begin(fighter.weaponSlotLevels), std::end(fighter.weaponSlotLevels), profile.weaponSlotLevels);
+    std::copy(std::begin(fighter.trinketSlotLevels), std::end(fighter.trinketSlotLevels), profile.trinketSlotLevels);
+    std::copy(std::begin(fighter.weaponItemLevels), std::end(fighter.weaponItemLevels), profile.weaponItemLevels);
+    std::copy(std::begin(fighter.trinketItemLevels), std::end(fighter.trinketItemLevels), profile.trinketItemLevels);
+    return profile;
+}
+
+// Online, a member's fighter appears, set up from their profile, in the colour they asked for if it's free. Returns
+// it, or -1 when the game is full.
+int Match::member_join(Sim& sim, int member, const Profile& profile)
+{
+    if (sim.fighterCount >= MAX_FIGHTERS)
+        return -1;
+    int index = sim.fighterCount++;
+    Fighter& fighter = sim.fighters[index];
+    fighter = Fighter{};
+    fighter.init(sim, index);
+    fighter.slots_set(std::clamp(profile.weaponSlots, 1, SLOT_MAX), std::clamp(profile.trinketSlots, 1, SLOT_MAX));
+    std::copy(std::begin(profile.weaponLoadout), std::end(profile.weaponLoadout), fighter.weaponLoadout);
+    std::copy(std::begin(profile.trinketLoadout), std::end(profile.trinketLoadout), fighter.trinketLoadout);
+    std::copy(std::begin(profile.weaponSlotLevels), std::end(profile.weaponSlotLevels), fighter.weaponSlotLevels);
+    std::copy(std::begin(profile.trinketSlotLevels), std::end(profile.trinketSlotLevels), fighter.trinketSlotLevels);
+    std::copy(std::begin(profile.weaponItemLevels), std::end(profile.weaponItemLevels), fighter.weaponItemLevels);
+    std::copy(std::begin(profile.trinketItemLevels), std::end(profile.trinketItemLevels), fighter.trinketItemLevels);
+    owners[index] = member;
+    std::memcpy(names[index], profile.name, sizeof(names[index]));
+    names[index][PLAYER_NAME_MAX] = '\0';
+    bool isTaken[COLOR_COUNT] = {};
+    for (int i = 0; i < index; i++)
+        isTaken[colors[i]] = true;
+    bool isFree = profile.color >= 0 && profile.color < COLOR_COUNT && !isTaken[profile.color];
+    colors[index] = isFree ? profile.color : (std::find(isTaken, isTaken + COLOR_COUNT, false) - isTaken) % COLOR_COUNT;
+    return index;
+}
+
+// Online, a member's fighter goes with its attacks, and the fighters after it move down a place.
+void Match::member_leave(Sim& sim, int member)
+{
+    int index = fighter_find(sim, member);
+    if (index < 0)
+        return;
+    std::vector<Attack>& attacks = sim.weapons.attacks;
+    std::erase_if(attacks, [&](Attack& attack) { return attack.owner == index; });
+    for (Attack& attack : attacks)
+        attack.owner -= attack.owner > index;
+    for (int i = index; i + 1 < sim.fighterCount; i++)
+    {
+        sim.fighters[i] = sim.fighters[i + 1];
+        sim.fighters[i].index = i;
+        sim.bot.states[i] = sim.bot.states[i + 1];
+        owners[i] = owners[i + 1];
+        colors[i] = colors[i + 1];
+        std::memcpy(names[i], names[i + 1], sizeof(names[i]));
+    }
+    queue_slots_shift(index, sim.fighterCount);
+    sim.fighterCount--;
+    owners[sim.fighterCount] = -1;
+}
+
+// Which fighter a member plays, or -1 for none.
+int Match::fighter_find(Sim& sim, int member)
+{
+    for (int i = 0; i < sim.fighterCount; i++)
+        if (owners[i] == member)
+            return i;
+    return -1;
+}

src/match.h

@@ -142,8 +142,25 @@ inline int pick_encode(bool isTrinket, int slot, int item)
         {.type = EDIT_ITEM, .isTrinket = isTrinket, .index = slot, .value = item < 0 ? EDIT_EMPTY : item});
 }
 
+// A player's setup as they join online: their name, the colour they'd like (-1 for any), and their sandbox slots,
+// loadouts, levels and stacking, which their fighter starts with. Plain data, sent as it sits in memory.
+struct Profile
+{
+    char name[PLAYER_NAME_MAX + 1] = {};
+    int color = -1;
+    int weaponSlots = SLOTS_DEFAULT;
+    int trinketSlots = SLOTS_DEFAULT;
+    int weaponLoadout[SLOT_MAX] = {};
+    int trinketLoadout[SLOT_MAX] = {};
+    int weaponSlotLevels[SLOT_MAX] = {};
+    int trinketSlotLevels[SLOT_MAX] = {};
+    int weaponItemLevels[WEAPON_COUNT] = {};
+    int trinketItemLevels[TRINKET_COUNT] = {};
+};
+
 // The default rules for a mode: a best-of-three deathmatch for two, or a three minute race for four.
 Rules rules_get(int mode);
+Profile profile_get(Fighter& fighter);
 Rules rules_clean(Rules rules);
 
 // Online, a game queued in the lobby's sandbox by one of its fighters: its rules, and the area on the ground where
@@ -221,6 +238,9 @@ public:
     int queue_startable_get(Sim& sim);
     bool is_queue_set(Sim& sim, int queuer);
     void queue_slots_shift(int from, int count);
+    int member_join(Sim& sim, int member, const Profile& profile);
+    void member_leave(Sim& sim, int member);
+    int fighter_find(Sim& sim, int member);
     int humans_left_get(Sim& sim);
 
 private:

src/protocol.h

@@ -22,8 +22,10 @@
 //
 // A signal's payload is either a description {sdp, kind} or a candidate {candidate, mid}.
 
+#include <cstring>
 #include <string>
 #include <string_view>
+#include <type_traits>
 
 constexpr int PROTOCOL_VERSION = 2;
 constexpr int LOBBY_MEMBERS_MAX = 4;
@@ -36,6 +38,35 @@ constexpr int KICK_REASON_MAX = 60;
 constexpr const char SERVER_URL_DEFAULT[] = "wss://shweetz.net/smack-a-brother/ws";
 constexpr int SERVER_URL_LENGTH = 128;
 
+// Packets are plain values one after another, as they sit in memory (every platform agrees on these layouts).
+struct PacketWriter
+{
+    std::string bytes;
+
+    template <class T> PacketWriter& put(const T& value)
+    {
+        static_assert(std::is_trivially_copyable_v<T>);
+        bytes.append(reinterpret_cast<const char*>(&value), sizeof(T));
+        return *this;
+    }
+};
+
+struct PacketReader
+{
+    const std::string& bytes;
+    size_t at = 0;
+
+    template <class T> bool get(T& value)
+    {
+        static_assert(std::is_trivially_copyable_v<T>);
+        if (at + sizeof(T) > bytes.size())
+            return false;
+        std::memcpy(static_cast<void*>(&value), bytes.data() + at, sizeof(T));
+        at += sizeof(T);
+        return true;
+    }
+};
+
 // Text from elsewhere (another player, or the server) made safe to show: only printable ASCII (what the game's font
 // has; anything else, emoji included, is dropped), cut to max characters, with spaces at its ends trimmed.
 inline std::string text_clean(std::string_view raw, size_t max)

src/session.cpp

@@ -35,35 +35,6 @@ enum PacketType : Uint8
     PACKET_QUEUE
 };
 
-// Packets are plain values one after another, as they sit in memory (every platform agrees on these layouts).
-struct PacketWriter
-{
-    std::string bytes;
-
-    template <class T> PacketWriter& put(const T& value)
-    {
-        static_assert(std::is_trivially_copyable_v<T>);
-        bytes.append(reinterpret_cast<const char*>(&value), sizeof(T));
-        return *this;
-    }
-};
-
-struct PacketReader
-{
-    const std::string& bytes;
-    size_t at = 0;
-
-    template <class T> bool get(T& value)
-    {
-        static_assert(std::is_trivially_copyable_v<T>);
-        if (at + sizeof(T) > bytes.size())
-            return false;
-        std::memcpy(static_cast<void*>(&value), bytes.data() + at, sizeof(T));
-        at += sizeof(T);
-        return true;
-    }
-};
-
 // Field by field, since the padding between them is whatever was in memory.
 static bool controls_same(const Controls& a, const Controls& b)
 {
@@ -125,18 +96,9 @@ Controls InputLog::guess(int at) const
 // This screen's player as they join: name, colour, and the sandbox fighter they're playing now.
 Profile Session::profile_get(Game& game)
 {
-    Profile profile;
+    Profile profile = ::profile_get(game.local_get());
-    Fighter& fighter = game.local_get();
     SDL_strlcpy(profile.name, game.settings.name, sizeof(profile.name));
     profile.color = game.settings.color_get();
-    profile.weaponSlots = fighter.weaponSlots;
-    profile.trinketSlots = fighter.trinketSlots;
-    std::copy(std::begin(fighter.weaponLoadout), std::end(fighter.weaponLoadout), profile.weaponLoadout);
-    std::copy(std::begin(fighter.trinketLoadout), std::end(fighter.trinketLoadout), profile.trinketLoadout);
-    std::copy(std::begin(fighter.weaponSlotLevels), std::end(fighter.weaponSlotLevels), profile.weaponSlotLevels);
-    std::copy(std::begin(fighter.trinketSlotLevels), std::end(fighter.trinketSlotLevels), profile.trinketSlotLevels);
-    std::copy(std::begin(fighter.weaponItemLevels), std::end(fighter.weaponItemLevels), profile.weaponItemLevels);
-    std::copy(std::begin(fighter.trinketItemLevels), std::end(fighter.trinketItemLevels), profile.trinketItemLevels);
     return profile;
 }
 
@@ -449,57 +411,10 @@ void Session::events_apply(Game& game, int at)
     {
         if (event.tick != at)
             continue;
-        if (event.type == EVENT_JOIN && game.sim.fighterCount < MAX_FIGHTERS)
+        if (event.type == EVENT_JOIN)
-        {
+            match.member_join(game.sim, event.member, event.profile);
-            int index = game.sim.fighterCount++;
-            Fighter& fighter = game.sim.fighters[index];
-            fighter = Fighter{};
-            fighter.init(game.sim, index);
-            const Profile& profile = event.profile;
-            fighter.slots_set(std::clamp(profile.weaponSlots, 1, SLOT_MAX),
-                              std::clamp(profile.trinketSlots, 1, SLOT_MAX));
-            std::copy(std::begin(profile.weaponLoadout), std::end(profile.weaponLoadout), fighter.weaponLoadout);
-            std::copy(std::begin(profile.trinketLoadout), std::end(profile.trinketLoadout), fighter.trinketLoadout);
-            std::copy(std::begin(profile.weaponSlotLevels), std::end(profile.weaponSlotLevels),
-                      fighter.weaponSlotLevels);
-            std::copy(std::begin(profile.trinketSlotLevels), std::end(profile.trinketSlotLevels),
-                      fighter.trinketSlotLevels);
-            std::copy(std::begin(profile.weaponItemLevels), std::end(profile.weaponItemLevels),
-                      fighter.weaponItemLevels);
-            std::copy(std::begin(profile.trinketItemLevels), std::end(profile.trinketItemLevels),
-                      fighter.trinketItemLevels);
-            match.owners[index] = event.member;
-            SDL_strlcpy(match.names[index], profile.name, sizeof(match.names[index]));
-            bool isTaken[COLOR_COUNT] = {};
-            for (int i = 0; i < index; i++)
-                isTaken[match.colors[i]] = true;
-            int color = profile.color >= 0 && profile.color < COLOR_COUNT && !isTaken[profile.color]
-                            ? profile.color
-                            : std::find(isTaken, isTaken + COLOR_COUNT, false) - isTaken;
-            match.colors[index] = color % COLOR_COUNT;
-        }
         if (event.type == EVENT_LEAVE)
-        {
+            match.member_leave(game.sim, event.member);
-            int index = std::find(match.owners, match.owners + game.sim.fighterCount, event.member) - match.owners;
-            if (index >= game.sim.fighterCount)
-                continue;
-            std::vector<Attack>& attacks = game.sim.weapons.attacks;
-            std::erase_if(attacks, [&](Attack& attack) { return attack.owner == index; });
-            for (Attack& attack : attacks)
-                attack.owner -= attack.owner > index;
-            for (int i = index; i + 1 < game.sim.fighterCount; i++)
-            {
-                game.sim.fighters[i] = game.sim.fighters[i + 1];
-                game.sim.fighters[i].index = i;
-                game.sim.bot.states[i] = game.sim.bot.states[i + 1];
-                match.owners[i] = match.owners[i + 1];
-                match.colors[i] = match.colors[i + 1];
-                SDL_memcpy(match.names[i], match.names[i + 1], sizeof(match.names[i]));
-            }
-            match.queue_slots_shift(index, game.sim.fighterCount);
-            game.sim.fighterCount--;
-            match.owners[game.sim.fighterCount] = -1;
-        }
         if (event.type == EVENT_QUEUE || event.type == EVENT_UNQUEUE)
         {
             int index = std::find(match.owners, match.owners + game.sim.fighterCount, event.member) - match.owners;

src/session.h

@@ -18,22 +18,6 @@ constexpr int SNAPSHOT_RING = 64;
 // A member's connection has no ping to show (it's this screen's own, hosting).
 constexpr float PING_NONE = -2;
 
-// A player's setup as they join online: their name, the colour they'd like (-1 for any), and their sandbox slots,
-// loadouts, levels and stacking, which their fighter starts with. Plain data, sent as it sits in memory.
-struct Profile
-{
-    char name[PLAYER_NAME_MAX + 1] = {};
-    int color = -1;
-    int weaponSlots = SLOTS_DEFAULT;
-    int trinketSlots = SLOTS_DEFAULT;
-    int weaponLoadout[SLOT_MAX] = {};
-    int trinketLoadout[SLOT_MAX] = {};
-    int weaponSlotLevels[SLOT_MAX] = {};
-    int trinketSlotLevels[SLOT_MAX] = {};
-    int weaponItemLevels[WEAPON_COUNT] = {};
-    int trinketItemLevels[TRINKET_COUNT] = {};
-};
-
 enum SessionEventType
 {
     EVENT_JOIN,

src/sim.cpp

@@ -26,6 +26,53 @@ void Sim::tick()
     world.update(*this);
 }
 
+// A fresh online game for some of a lobby's fighters (by index) to play by the rules, bots filling the rest when the
+// rules say to. Their members, names and colours come along, and it starts from the seed, so everyone builds the same
+// one. The bots keep their difficulty.
+void Sim::game_start(Match& lobby, const int* members, int count, const Rules& rules, Uint32 seed)
+{
+    int owners[MAX_FIGHTERS];
+    int colors[MAX_FIGHTERS];
+    char names[MAX_FIGHTERS][PLAYER_NAME_MAX + 1];
+    for (int k = 0; k < count; k++)
+    {
+        owners[k] = lobby.owners[members[k]];
+        colors[k] = lobby.colors[members[k]];
+        std::memcpy(names[k], lobby.names[members[k]], sizeof(names[k]));
+    }
+    int players = rules.isBotFill ? std::max(rules.players, count) : count;
+    int level = bot.level;
+    bot = Bot{};
+    bot.level = level;
+    weapons = Weapons{};
+    world = World{};
+    match = Match{};
+    match.rules = rules;
+    match.rules.players = players;
+    match.isOnline = true;
+    rng.state = seed ? seed : RNG_SEED;
+    fighterCount = players;
+
+    bool isTaken[COLOR_COUNT] = {};
+    for (int k = 0; k < count; k++)
+        isTaken[colors[k] % COLOR_COUNT] = true;
+    for (int k = 0; k < players; k++)
+    {
+        fighters[k] = Fighter{};
+        fighters[k].init(*this, k);
+        match.owners[k] = k < count ? owners[k] : -1;
+        if (k < count)
+        {
+            match.colors[k] = colors[k];
+            std::memcpy(match.names[k], names[k], sizeof(match.names[k]));
+            continue;
+        }
+        match.colors[k] = std::find(isTaken, isTaken + COLOR_COUNT, false) - isTaken;
+        isTaken[match.colors[k]] = true;
+    }
+    match.start(*this);
+}
+
 // Moves a level by a step within the levels there are, cueing whether it went up or down.
 void level_step(Sim& sim, int& level, int step)
 {

src/sim.h

@@ -56,6 +56,7 @@ struct Sim
 
     void init(Uint32 seed);
     void tick();
+    void game_start(Match& lobby, const int* members, int count, const Rules& rules, Uint32 seed);
     Snapshot snapshot_save();
     void snapshot_load(Snapshot& snapshot);
     Uint32 checksum_get();