scenebootstrapper script added to load startup scene from any scene

Assets/BossRoom/Scripts/Editor/SceneBootstrapper.cs

@@ -0,0 +1,122 @@
+using UnityEditor;
+using UnityEditor.SceneManagement;
+using UnityEngine;
+
+namespace BossRoom.Scripts.Editor
+{
+    /// <summary>
+    /// Class that permits auto-loading a bootstrap scene when the editor switches play state. This class is
+    /// initialized when Unity loads and when scripts are recompiled. This is to be able to subscribe to
+    /// EditorApplication's playModeStateChanged event, which is when we wish to open a new scene.
+    /// </summary>
+    [InitializeOnLoad]
+    public class SceneBootstrapper
+    {
+        const string k_BootstrapSceneKey = "BootstrapScene";
+        const string k_PreviousSceneKey = "PreviousScene";
+        const string k_LoadBootstrapSceneKey = "LoadBootstrapScene";
+
+        const string k_LoadBootstrapSceneOnPlay = "Boss Room/Load Bootstrap Scene On Play";
+        const string k_DoNotLoadBootstrapSceneOnPlay = "Boss Room/Don't Load Bootstrap Scene On Play";
+
+        static string BootstrapScene
+        {
+            get
+            {
+                if (!EditorPrefs.HasKey(k_BootstrapSceneKey))
+                {
+                    EditorPrefs.SetString(k_BootstrapSceneKey, EditorBuildSettings.scenes[0].path);
+                }
+                return EditorPrefs.GetString(k_BootstrapSceneKey, EditorBuildSettings.scenes[0].path);
+            }
+            set => EditorPrefs.SetString(k_BootstrapSceneKey, value);
+        }
+
+        static string PreviousScene
+        {
+            get => EditorPrefs.GetString(k_PreviousSceneKey);
+            set => EditorPrefs.SetString(k_PreviousSceneKey, value);
+        }
+
+        static bool LoadBootstrapScene
+        {
+            get
+            {
+                if (!EditorPrefs.HasKey(k_LoadBootstrapSceneKey))
+                {
+                    EditorPrefs.SetBool(k_LoadBootstrapSceneKey, true);
+                }
+                return EditorPrefs.GetBool(k_LoadBootstrapSceneKey, true);
+            }
+            set => EditorPrefs.SetBool(k_LoadBootstrapSceneKey, value);
+        }
+
+        static SceneBootstrapper()
+        {
+            EditorApplication.playModeStateChanged += EditorApplicationOnplayModeStateChanged;
+        }
+
+        [MenuItem(k_LoadBootstrapSceneOnPlay, true)]
+        static bool ShowLoadBootstrapSceneOnPlay()
+        {
+            return !LoadBootstrapScene;
+        }
+
+        [MenuItem(k_LoadBootstrapSceneOnPlay)]
+        static void EnableLoadBootstrapSceneOnPlay()
+        {
+            LoadBootstrapScene = true;
+        }
+
+        [MenuItem(k_DoNotLoadBootstrapSceneOnPlay, true)]
+        static bool ShowDoNotLoadBootstrapSceneOnPlay()
+        {
+            return LoadBootstrapScene;
+        }
+
+        [MenuItem(k_DoNotLoadBootstrapSceneOnPlay)]
+        static void DisableDoNotLoadBootstrapSceneOnPlay()
+        {
+            LoadBootstrapScene = false;
+        }
+
+        static void EditorApplicationOnplayModeStateChanged(PlayModeStateChange obj)
+        {
+            if (!LoadBootstrapScene)
+            {
+                return;
+            }
+
+            if (obj == PlayModeStateChange.ExitingEditMode)
+            {
+                // cache previous scene so we return to this scene after play session, if possible
+                PreviousScene = EditorSceneManager.GetActiveScene().path;
+
+                if (EditorSceneManager.SaveCurrentModifiedScenesIfUserWantsTo())
+                {
+                    // user either hit "Save" or "Don't Save"; open bootstrap scene
+
+                    if (!string.IsNullOrEmpty(BootstrapScene) &&
+                        System.Array.Exists(EditorBuildSettings.scenes, scene => scene.path == BootstrapScene))
+                    {
+                        // scene is included in build settings; open it
+                        EditorSceneManager.OpenScene(BootstrapScene);
+                    }
+                }
+                else
+                {
+                    // user either hit "Cancel" or exited window; don't open bootstrap scene & return to editor
+
+                    EditorApplication.isPlaying = false;
+                }
+            }
+            else if (obj == PlayModeStateChange.EnteredEditMode)
+            {
+                if (!string.IsNullOrEmpty(PreviousScene))
+                {
+                    EditorSceneManager.OpenScene(PreviousScene);
+                }
+            }
+        }
+    }
+}