Using memory arena in the game that supports hot reload

Game/game.cpp

@@ -3,6 +3,8 @@
 #undef min
 #undef max
 
+#include <game.h>
+
 #include <Core/HAL/Filesystem/Filesystem.h>
 #include <Core/JulietInit.h>
 #include <Core/Logging/LogManager.h>
@@ -10,6 +12,12 @@
 #include <Entity/Entity.h>
 #include <Entity/EntityManager.h>
 
+GameState* gGameState = nullptr;
+GameState* GetGameState()
+{
+    return gGameState;
+}
+
 // Test code
 namespace Game
 {
@@ -26,56 +34,59 @@ namespace Game
         int Health;
     };
     DEFINE_ENTITY(Rock);
-
 } // namespace Game
 
-using namespace Juliet;
-
-extern "C" JULIET_API void GameInit(GameInitParams* params)
-{
-    // Example allocation in GameArena
-    struct GameState
-    {
-        float TotalTime;
-        int   Score;
-    };
-
-    auto* gameState      = ArenaPushStruct<GameState>(params->GameArena);
-    gameState->TotalTime = 0.0f;
-    gameState->Score     = 0;
-
-    printf("Game Arena Allocated: %p\n", static_cast<void*>(gameState));
-
-    using namespace Game;
-
-    // Entity Use case
-    InitEntityManager(params->GameArena);
-    auto& manager  = GetEntityManager();
-    Door* door     = MakeEntity<Door>(manager, 10.0f, 2.0f);
-    door->IsOpened = true;
-
-    Entity*                ent       = door->Base;
-    [[maybe_unused]] Door* stillDoor = DownCast<Door>(ent);
-    Assert(door == stillDoor);
-
-    Rock* rock   = MakeEntity<Rock>(manager, 1.f, 2.f);
-    rock->Health = 100;
-    Assert(door->Base != rock->Base);
-
-    printf("Door is %s\n", door->IsOpened ? "Opened" : "Closed");
-    printf("Rock has %d health points\n", rock->Health);
-}
-
 extern "C" JULIET_API void __cdecl GameShutdown()
 {
     printf("Shutting down game...\n");
 
+    using namespace Juliet;
     using namespace Game;
 
     ShutdownEntityManager();
 }
 
-extern "C" JULIET_API void __cdecl GameUpdate([[maybe_unused]] float deltaTime)
+extern "C" JULIET_API void __cdecl GameUpdate(Juliet::GameData* params, [[maybe_unused]] float deltaTime)
 {
+    using namespace Juliet;
+    using namespace Game;
+
+    gGameState = params->GameState;
+    if (!gGameState)
+    {
+        Arena* gameStateArena = ArenaAllocate({ .ReserveSize = Megabytes(1) } JULIET_DEBUG_PARAM("Game Total Arena"));
+        auto*  gameState      = ArenaPushStruct<GameState>(gameStateArena);
+        gGameState = params->GameState = gameState;
+        gameState->TotalArena          = gameStateArena;
+
+        gameState->TotalTime = 0.0f;
+        gameState->Score     = 0;
+
+        printf("Game Arena Allocated: %p\n", static_cast<void*>(gameState));
+
+        // Bootstrap world
+        auto*  worldArena            = ArenaAllocate({ .ReserveSize = Megabytes(1) } JULIET_DEBUG_PARAM("World Arena"));
+        World* world                 = ArenaPushStruct<World>(worldArena JULIET_DEBUG_PARAM("World"));
+        gameState->World             = world;
+        gameState->World->WorldArena = worldArena;
+
+        // Entity Use case
+        InitEntityManager(gameState->World);
+        auto& manager  = GetEntityManager();
+        Door* door     = MakeEntity<Door>(manager, 10.0f, 2.0f);
+        door->IsOpened = true;
+
+        Entity*                ent       = door->Base;
+        [[maybe_unused]] Door* stillDoor = DownCast<Door>(ent);
+        Assert(door == stillDoor);
+
+        Rock* rock   = MakeEntity<Rock>(manager, 1.f, 2.f);
+        rock->Health = 100;
+        Assert(door->Base != rock->Base);
+
+        printf("Door is %s\n", door->IsOpened ? "Opened" : "Closed");
+        printf("Rock has %d health points\n", rock->Health);
+    }
+
     // printf("Updating game...\n");
 }