implement nextEntityID save/load

src/frontend/debug_panel.cpp

@@ -85,7 +85,8 @@ std::shared_ptr<UINode> create_debug_panel(
                L" visible: "+std::to_wstring(level->chunks->visible);
     }));
     panel->add(create_label([=]() {
-        return L"entities: "+std::to_wstring(level->entities->size());
+        return L"entities: "+std::to_wstring(level->entities->size())+L" next: "+
+               std::to_wstring(level->entities->peekNextID());
     }));
     panel->add(create_label([=](){
         const auto& vox = player->selection.vox;

src/objects/Entities.hpp

@@ -192,9 +192,17 @@ public:
     void despawn(entityid_t id);
     dynamic::Value serialize(const Entity& entity);
 
+    void setNextID(entityid_t id) {
+        nextID = id;
+    }
+
     inline size_t size() const {
         return entities.size();
     }
+
+    inline entityid_t peekNextID() const {
+        return nextID;
+    }
 };
 
 #endif // OBJECTS_ENTITIES_HPP_

src/world/Level.cpp

@@ -26,6 +26,7 @@ Level::Level(
     entities(std::make_unique<Entities>(this)),
 	settings(settings)
 {
+    entities->setNextID(this->world->nextEntityId);
 	auto inv = std::make_shared<Inventory>(
         this->world->getNextInventoryId(), DEF_PLAYER_INVENTORY_SIZE
     );

src/world/World.cpp

@@ -9,10 +9,12 @@
 #include "../files/WorldFiles.hpp"
 #include "../items/Inventories.hpp"
 #include "../objects/Player.hpp"
+#include "../objects/Entities.hpp"
 #include "../voxels/Chunk.hpp"
 #include "../voxels/Chunks.hpp"
 #include "../voxels/ChunksStorage.hpp"
 #include "../world/WorldGenerators.hpp"
+#include "Level.hpp"
 
 #include <memory>
 #include <glm/glm.hpp>
@@ -52,6 +54,7 @@ void World::updateTimers(float delta) {
 void World::write(Level* level) {
     const Content* content = level->content;
     level->chunks->saveAll();
+    nextEntityId = level->entities->peekNextID();
     wfile->write(this, content);
     auto playerFile = dynamic::Map();
 
@@ -193,6 +196,7 @@ void World::deserialize(dynamic::Map* root) {
         weatherobj->num("fog", fog);
     }
     nextInventoryId = root->get("next-inventory-id", 2);
+    nextEntityId = root->get("next-entity-id", 1);
 }
 
 std::unique_ptr<dynamic::Map> World::serialize() const {
@@ -215,5 +219,6 @@ std::unique_ptr<dynamic::Map> World::serialize() const {
     weatherobj.put("fog", fog);
 
     root->put("next-inventory-id", nextInventoryId);
+    root->put("next-entity-id", nextEntityId);
     return root;
 }

src/world/World.hpp

@@ -51,6 +51,8 @@ public:
     /// @brief will be replaced with weather in future 
     float fog = 0.0f;
 
+    entityid_t nextEntityId = 0;
+
     World(
         std::string name, 
         std::string generator,