Code explanation

Some non relevant code is omitted.

1. BGCollectable.cs- This script is attached to every collectable object. This script is hooked to a database by extending from BGM_Collectable class (generated by code generator), which in turn is extended from BGEntityGo- our component we use to connect GameObjects to database. When new collectable object is spawned in the scene by BGSpawner.cs, Entity field is assigned- and object become linked to a particular table row.
   This script has 4 tasks:
   1. Show gold amount on the TextMesh component. This is done by this code Text.text = "Gold:" + m_gold;. m_gold field reads/write data from/to database
   2. Add some gold to the player
   3. Play sound effect when object's collected.
   4. Remove the object when it's collected from scene and from database.

   
   public class BGCollectable : BGM_Collectable
   {
       //this callback is called then connected entity is changed
       public override void EntityChanged()
       {
           Text.text = "Gold:" + m_gold;
       }
   
       private void OnTriggerEnter(Collider other)
       {
           if (other.gameObject.CompareTag("Player"))
           {
               var player = other.GetComponent<BGPlayer>();
   
               //add gold
               player.m_gold += m_gold;
   
               //play sound
               var audioSource = player.GetComponent<AudioSource>();
               audioSource.clip = m_type.f_audio;
               audioSource.Play();
   
               //remove from database & scene
               Entity.Delete();
               Destroy(gameObject);
           }
       }
   }
           

2. BGGoToScene.cs- this script is attached to a portal to another scene. When the player collides with this portal, he's moved to another scene. This script is also hooked up to a database, namely to Scene row, pointing to a scene to load. When the player collides with this object, script read data about this scene from database, updates Player table with position and rotation from Scene table and loads target scene.

   
   public class BGGoToScene : BGM_Scene
   {
       private void OnTriggerEnter(Collider other)
       {
           if (other.gameObject.CompareTag("Player"))
           {
               //get reference to player
               var player = other.GetComponent<BGPlayer>();
   
               //set player position & rotation to scene's spawn position & rotation
               player.m_position = m_spawnPosition;
               player.m_rotation = Quaternion.Euler(m_spawnRotation);
   
               //load the scene
               SceneManager.LoadScene(Entity.Name);
           }
       }
   }
           

3. BGSpawner.cs- this script fills database with new objects and also spawn them to the scene. It hooked up to Scene table. It uses database events, to find the moment all objects are collected.

   
   public class BGSpawner :BGM_Scene
   {
       public override void  Start()
       {
           base.Start();
           Spawn();
           //use database events to keep track the moment, when all collectables are gathered
           BGRepo.I.Events.AddAnyEntityDeletedListener(BGE_Collectable.MetaDefault.Id, CheckForNewSpawns);
       }
   
       public override void OnDestroy()
       {
           base.OnDestroy();
           BGRepo.I.Events.RemoveAnyEntityDeletedListener(BGE_Collectable.MetaDefault.Id, CheckForNewSpawns);
       }
   
       //spawn unity's gameobjects - corresponding to Repo objects
       private void Spawn()
       {
           //fetch collectables from database
           var collectables = m_Collectable;
   
           //no collectables- no luck
           if (BGUtil.IsEmpty(collectables)) return;
   
           //spawn collectables objects
           foreach (BGEntity collectable in collectables)
           {
               //create collectable GameObject
               var newCollectable = Instantiate(collectable.f_type.f_prefab,
                   collectable.f_position, Quaternion.identity);
   
               //we know - collectable prefab has BGCollectable script attached
               // so hook it up to table's row
               newCollectable.GetComponent<BGCollectable>().Entity = collectable;
           }
       }
   
       //This method create new collectables randomly for all scenes if all objects are collected
       public void CheckForNewSpawns(object sender, BGEventArgsAnyEntity args)
       {
           //there are still some collectables
           if (BGE_Collectable.CountEntities > 0) return;
   
           //ok, we gathered all objects- lets spawn new ones
           BGE_Scene.ForEachEntity(scene =>
           {
   
               //number of collectables for one scene
               var count = Random.Range(3, 6);
               for (var i = 0; i < count; i++)
               {
                   //nested meta has utility method, which auto assign new collectable to owner entity (scene)
                   var newCollectable = BGE_Collectable.NewEntity(scene);
   
                   //set gold
                   newCollectable.f_gold = Random.Range(1, 10);
   
                   //bounds determines scene's frontiers
                   var bounds = scene.f_bounds;
                   //set position
                   newCollectable.f_position = new Vector3(Random.Range(bounds.min.x, bounds.max.x),
                       bounds.center.y, Random.Range(bounds.min.z, bounds.max.z));
   
                   //set type
                   newCollectable.f_type = BGE_CollectableType.GetEntity(Random.Range(0, BGE_CollectableType.CountEntities));
               }
           });
   
           //spawn GameObjects for current scene
           Spawn();
       }
   }
           

4. BGPlayer.cs- this script is attached to the player and hooked up to a first row of Player table via extending from BGM_Player.
   1. It initializes its position and rotation from database in the Start method
   2. It implements BGAddonSaveLoad.BeforeSaveReciever interface to ensure OnBeforeSave method is called before saving. In this method it saves its own position and amount of gold to the database, so while saving those values will be put to the save file.

   
   public class BGPlayer : BGM_Player, BGAddonSaveLoad.BeforeSaveReciever
   {
       public override void Start()
       {
           base.Start();
           //get pos and rotation from the table
           transform.position = m_position;
           transform.rotation = m_rotation;
       }
   
       //this method is called before saving
       void BGAddonSaveLoad.BeforeSaveReciever.OnBeforeSave()
       {
           //save current position, rotation and scene to the database
           m_position = transform.position;
           m_rotation = transform.rotation;
           m_scene = BGE_Scene.FindEntity(scene => string.Equals(scene.Name, SceneManager.GetActiveScene().name));
       }
   }
           

5. BGSavingLoading.cs It Provides Save/Load functions via SaveLoad addon. More information about Save/Load addon can be found here

   
   public class BGSavingLoading : MonoBehaviour
   {
       //... some code is omitted
       public void Save()
       {
           //save
           var bytes = BGRepo.I.Addons.Get<BGAddonSaveLoad>().Save();
           File.WriteAllBytes(SaveFilePath, bytes);
       }
   
       public void Load()
       {
           //load
           if (!HasSavedFile) return;
   
           var content = File.ReadAllBytes(SaveFilePath);
   
           BGRepo.I.Addons.Get<BGAddonSaveLoad>().Load(content);
   
           //load saved scene
           SceneManager.LoadScene(R.Player.d_scene.Get(PlayerEntity).Name);
       }
   }