feat(#141): add game manager

Assets/Scripts/Construction/BuildingSelectionUI.cs

@@ -43,8 +43,8 @@ private void Start()
             LoadButtons();
             exitButton.onClick.AddListener(Close);
             gameObject.SetActive(false);
-            playerCamera = mainCamera.GetComponent<PlayerCamera>();
-            playerConstructionHandler = player.GetComponent<PlayerConstructionHandler>();
+            playerCamera = GameManager.PlayerCamera;
+            playerConstructionHandler = GameManager.GetPlayerComponent<PlayerConstructionHandler>();
         }
 
         private void LateUpdate()

Assets/Scripts/GameManager.cs

@@ -0,0 +1,102 @@
+using System.Collections.Generic;
+using System.Linq;
+using Cosmobot.Utils;
+using UnityEngine;
+using UnityEngine.SceneManagement;
+
+namespace Cosmobot
+{
+    [DefaultExecutionOrder(ExecutionOrder.GameManager)]
+    public class GameManager : SingletonSystem<GameManager>
+    {
+        private Scene? playerScene;
+        private Transform playerTransform;
+        private PlayerController playerController;
+        private PlayerCamera playerCamera;
+
+        public static Transform PlayerTransform => SemiSafeGetPlayer(Instance.playerTransform);
+        public static PlayerController PlayerController => SemiSafeGetPlayer(Instance.playerController);
+        public static PlayerCamera PlayerCamera => SemiSafeGetPlayer(Instance.playerCamera);
+
+        public static T GetPlayerComponent<T>() where T : class
+        {
+            return SemiSafeGetPlayer(Instance.playerTransform.GetComponent<T>());
+        }
+
+        private static T SemiSafeGetPlayer<T>(T o) where T : class
+        {
+#if UNITY_EDITOR
+            Scene? scene = Instance.playerScene;
+            if (!scene.HasValue || !scene.Value.isLoaded || !Instance.playerTransform)
+            {
+                Debug.LogWarning("Accessing unloaded player!");
+                return null;
+            }
+#endif
+            return o;
+        }
+
+        protected override void SystemAwake()
+        {
+            SceneManager.sceneLoaded += OnSceneLoad;
+            SceneManager.sceneUnloaded += OnSceneUnload;
+            // first setup
+            OnSceneLoad(SceneManager.GetActiveScene(), LoadSceneMode.Single);
+        }
+
+        void OnSceneLoad(Scene _, LoadSceneMode _1)
+        {
+            SetupPlayer();
+        }
+
+        void OnSceneUnload(Scene scene)
+        {
+            if (scene.IsValid() && scene.isLoaded && scene != playerScene) return;
+            ClearPlayer();
+        }
+
+        void ClearPlayer()
+        {
+            playerScene = null;
+            playerTransform = null;
+            playerController = null;
+            playerCamera = null;
+        }
+
+        void SetupPlayer()
+        {
+            if (playerTransform) // will also check if object is valid
+            {
+                return;
+            }
+
+            GameObject[] playerObjects = GameObject.FindGameObjectsWithTag(Tags.Player);
+            List<GameObject> playerCandidates = playerObjects.Where(IsValidPlayerCandidate).ToList();
+            if (playerCandidates.Count == 0)
+            {
+                return;
+            }
+
+            GameObject selectedPlayer = playerCandidates[0];
+            if (playerCandidates.Count > 1)
+            {
+                string playerObjectsNames = playerObjects.Skip(1).Select(g => g.name).Aggregate((a, b) => $"{a}, '{b}'");
+                Debug.LogWarning($"Found multiple GameObject that appear to be an Player GameObjects" +
+                                 $"Using first one (click to select used object)." +
+                                 $"Other found objects: {playerObjectsNames}", selectedPlayer);
+            }
+
+            playerTransform = selectedPlayer.transform;
+            playerController = selectedPlayer.GetComponent<PlayerController>();
+            playerCamera = selectedPlayer.GetComponentInChildren<PlayerCamera>();
+            playerScene = selectedPlayer.scene; // use accusal GO scene
+        }
+
+        bool IsValidPlayerCandidate(GameObject playerCandidate)
+        {
+            return playerCandidate
+                && playerCandidate.GetComponent<PlayerController>()
+                && playerCandidate.GetComponentInChildren<PlayerCamera>();
+        }
+    }
+}

Assets/Scripts/Utils/SingletonSystem.cs

@@ -1,3 +1,4 @@
+using UnityEditor;
 using UnityEngine;
 
 namespace Cosmobot.Utils
@@ -27,6 +28,10 @@ protected virtual void OnDisable()
         {
             if (!ReferenceEquals(Instance, this)) return;
 
+#if UNITY_EDITOR
+            // prevent log warning (and keeping enabled) when exiting playmode
+            if (Application.exitCancellationToken.IsCancellationRequested) return;
+#endif
             enabled = true;
             Debug.LogWarning($"SingletonSystem {typeof(T).Name} cannot be disabled", this);
         }
@@ -37,6 +42,10 @@ protected void OnDestroy()
             {
                 SystemOnDestroy();
                 Instance = null;
+#if UNITY_EDITOR
+                // prevent log warning when exiting playmode
+                if (Application.exitCancellationToken.IsCancellationRequested) return;
+#endif
                 Debug.LogWarning($"SingletonSystem {typeof(T).Name} unregistered", this);
             }
         }

Assets/Scripts/Utils/Tags.cs

@@ -4,5 +4,6 @@ public static class Tags
     {
         public const string Item = "Item";
         public const string Enemy = "Enemy";
+        public const string Player = "Player";
     }
 }