Refactor WASM exports and add push-based player count events

Move WASM exports (mp_set_walk_animation, mp_set_idle_animation,
mp_trigger_emote) from multiplayer.cpp into a dedicated
wasm_exports.cpp, added to the isle target (guarded by both
EMSCRIPTEN and ISLE_EXTENSIONS) so the linker keeps the symbols.

Replace the polling mp_get_player_count export with push-based
playerCountChanged CustomEvents dispatched from NetworkManager.
The count only reflects players visible in the Isle world: null
when the local player is outside Isle, filtered by remote player
worldId when inside. Remove the now-unused GetPlayerCount() method.

CMakeLists.txt

@@ -15,8 +15,6 @@ endif()
 if (EMSCRIPTEN)
   add_compile_options(-pthread)
   add_link_options(-sUSE_WEBGL2=1 -sMIN_WEBGL_VERSION=2 -sALLOW_MEMORY_GROWTH=1 -sMAXIMUM_MEMORY=2gb -sUSE_PTHREADS=1 -sPROXY_TO_PTHREAD=1 -sOFFSCREENCANVAS_SUPPORT=1 -sPTHREAD_POOL_SIZE_STRICT=0 -sFORCE_FILESYSTEM=1 -sWASMFS=1 -sEXIT_RUNTIME=1)
-  add_link_options("-sEXPORTED_FUNCTIONS=[\"_main\",\"_mp_set_walk_animation\",\"_mp_set_idle_animation\",\"_mp_trigger_emote\",\"_mp_get_player_count\"]")
-  add_link_options("-sEXPORTED_RUNTIME_METHODS=[\"ccall\",\"cwrap\"]")
   set(SDL_PTHREADS ON CACHE BOOL "Enable SDL pthreads" FORCE)
 endif()
 
@@ -595,6 +593,11 @@ if (ISLE_BUILD_APP)
       ISLE/emscripten/messagebox.cpp
       ISLE/emscripten/window.cpp
     )
+    if(ISLE_EXTENSIONS)
+      target_sources(isle PRIVATE
+        extensions/src/multiplayer/wasm_exports.cpp
+      )
+    endif()
     target_compile_definitions(isle PRIVATE "ISLE_EMSCRIPTEN_HOST=\"${ISLE_EMSCRIPTEN_HOST}\"")
     set_property(TARGET isle PROPERTY SUFFIX ".html")
   endif()

extensions/include/extensions/multiplayer/networkmanager.h

@@ -44,7 +44,6 @@ class NetworkManager : public MxCore {
 	void SetWalkAnimation(uint8_t p_index);
 	void SetIdleAnimation(uint8_t p_index);
 	void SendEmote(uint8_t p_emoteId);
-	int GetPlayerCount() const;
 
 	void OnWorldEnabled(LegoWorld* p_world);
 	void OnWorldDisabled(LegoWorld* p_world);
@@ -71,6 +70,7 @@ class NetworkManager : public MxCore {
 	void RemoveRemotePlayer(uint32_t p_peerId);
 	void RemoveAllRemotePlayers();
 
+	void NotifyPlayerCountChanged();
 	int8_t DetectLocalVehicleType();
 
 	// Serialize and send a fixed-size message via the transport

extensions/src/multiplayer.cpp

@@ -125,42 +125,3 @@ bool Extensions::IsMultiplayerRejected()
 {
 	return Extension<MultiplayerExt>::Call(CheckRejected).value_or(FALSE);
 }
-
-#ifdef __EMSCRIPTEN__
-extern "C" {
-
-EMSCRIPTEN_KEEPALIVE void mp_set_walk_animation(int index)
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		mgr->SetWalkAnimation(static_cast<uint8_t>(index));
-	}
-}
-
-EMSCRIPTEN_KEEPALIVE void mp_set_idle_animation(int index)
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		mgr->SetIdleAnimation(static_cast<uint8_t>(index));
-	}
-}
-
-EMSCRIPTEN_KEEPALIVE void mp_trigger_emote(int index)
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		mgr->SendEmote(static_cast<uint8_t>(index));
-	}
-}
-
-EMSCRIPTEN_KEEPALIVE int mp_get_player_count()
-{
-	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
-	if (mgr) {
-		return mgr->GetPlayerCount();
-	}
-	return 0;
-}
-
-} // extern "C"
-#endif

extensions/src/multiplayer/networkmanager.cpp

@@ -11,6 +11,9 @@
 #include <SDL3/SDL_stdinc.h>
 #include <SDL3/SDL_timer.h>
 #include <vector>
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
 
 using namespace Multiplayer;
 
@@ -145,6 +148,8 @@ void NetworkManager::OnWorldEnabled(LegoWorld* p_world)
 				}
 			}
 		}
+
+		NotifyPlayerCountChanged();
 	}
 }
 
@@ -160,6 +165,8 @@ void NetworkManager::OnWorldDisabled(LegoWorld* p_world)
 		for (auto& [peerId, player] : m_remotePlayers) {
 			player->SetVisible(false);
 		}
+
+		NotifyPlayerCountChanged();
 	}
 }
 
@@ -338,6 +345,7 @@ void NetworkManager::HandleJoin(const PlayerJoinMsg& p_msg)
 	}
 
 	CreateAndSpawnPlayer(peerId, p_msg.actorId);
+	NotifyPlayerCountChanged();
 }
 
 void NetworkManager::HandleLeave(const PlayerLeaveMsg& p_msg)
@@ -356,6 +364,7 @@ void NetworkManager::HandleState(const PlayerStateMsg& p_msg)
 		}
 
 		CreateAndSpawnPlayer(peerId, p_msg.actorId);
+		NotifyPlayerCountChanged();
 		it = m_remotePlayers.find(peerId);
 	}
 
@@ -367,12 +376,20 @@ void NetworkManager::HandleState(const PlayerStateMsg& p_msg)
 		it = m_remotePlayers.find(peerId);
 	}
 
+	int8_t oldWorldId = it->second->GetWorldId();
+
 	it->second->UpdateFromNetwork(p_msg);
 
 	bool bothInIsle = m_inIsleWorld && (p_msg.worldId == (int8_t) LegoOmni::e_act1);
 	if (it->second->IsSpawned()) {
 		it->second->SetVisible(bothInIsle);
 	}
+
+	bool wasInIsle = (oldWorldId == (int8_t) LegoOmni::e_act1);
+	bool nowInIsle = (p_msg.worldId == (int8_t) LegoOmni::e_act1);
+	if (m_inIsleWorld && wasInIsle != nowInIsle) {
+		NotifyPlayerCountChanged();
+	}
 }
 
 void NetworkManager::HandleHostAssign(const HostAssignMsg& p_msg)
@@ -413,12 +430,6 @@ void NetworkManager::SendEmote(uint8_t p_emoteId)
 	SendMessage(msg);
 }
 
-int NetworkManager::GetPlayerCount() const
-{
-	// +1 for the local player
-	return static_cast<int>(m_remotePlayers.size()) + 1;
-}
-
 void NetworkManager::HandleEmote(const EmoteMsg& p_msg)
 {
 	uint32_t peerId = p_msg.header.peerId;
@@ -434,6 +445,7 @@ void NetworkManager::RemoveRemotePlayer(uint32_t p_peerId)
 	if (it != m_remotePlayers.end()) {
 		it->second->Despawn();
 		m_remotePlayers.erase(it);
+		NotifyPlayerCountChanged();
 	}
 }
 
@@ -443,6 +455,32 @@ void NetworkManager::RemoveAllRemotePlayers()
 		player->Despawn();
 	}
 	m_remotePlayers.clear();
+	NotifyPlayerCountChanged();
+}
+
+void NetworkManager::NotifyPlayerCountChanged()
+{
+#ifdef __EMSCRIPTEN__
+	int count = -1;
+	if (m_inIsleWorld) {
+		count = 1; // local player
+		for (auto& [peerId, player] : m_remotePlayers) {
+			if (player->GetWorldId() == (int8_t) LegoOmni::e_act1) {
+				count++;
+			}
+		}
+	}
+	// clang-format off
+	MAIN_THREAD_EM_ASM({
+		var canvas = Module.canvas;
+		if (canvas) {
+			canvas.dispatchEvent(new CustomEvent('playerCountChanged', {
+				detail: { count: $0 < 0 ? null : $0 }
+			}));
+		}
+	}, count);
+	// clang-format on
+#endif
 }
 
 int8_t NetworkManager::DetectLocalVehicleType()

extensions/src/multiplayer/wasm_exports.cpp

@@ -0,0 +1,38 @@
+#ifdef __EMSCRIPTEN__
+
+#include "extensions/multiplayer.h"
+#include "extensions/multiplayer/networkmanager.h"
+
+#include <emscripten.h>
+
+using namespace Extensions;
+
+extern "C" {
+
+EMSCRIPTEN_KEEPALIVE void mp_set_walk_animation(int index)
+{
+	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
+	if (mgr) {
+		mgr->SetWalkAnimation(static_cast<uint8_t>(index));
+	}
+}
+
+EMSCRIPTEN_KEEPALIVE void mp_set_idle_animation(int index)
+{
+	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
+	if (mgr) {
+		mgr->SetIdleAnimation(static_cast<uint8_t>(index));
+	}
+}
+
+EMSCRIPTEN_KEEPALIVE void mp_trigger_emote(int index)
+{
+	Multiplayer::NetworkManager* mgr = MultiplayerExt::GetNetworkManager();
+	if (mgr) {
+		mgr->SendEmote(static_cast<uint8_t>(index));
+	}
+}
+
+} // extern "C"
+
+#endif