Added Unity project files

Packages/com.vrchat.worlds/Editor/VRCSDK/SDK3/VRCSceneTemplateInitializer.cs

@@ -0,0 +1,43 @@
+using System.IO;
+using UnityEditor;
+using UnityEditor.SceneTemplate;
+using UnityEngine;
+
+/// <summary>Initialize the default VRC world scene from a template when the project is first launched</summary>
+[InitializeOnLoad]
+public class VRCSceneTemplateInitializer
+{
+    private const string SceneTemplatePath = "Packages/com.vrchat.worlds/Editor/VRCSDK/SDK3/VRCDefaultWorldScene.scenetemplate";
+    private const string ScenePath = "Assets/Scenes/VRCDefaultWorldScene.unity";
+    private const string HasRunStateKey = "VRCSceneTemplateInitializer_HasRun";
+    
+    // called on editor launch or domain reload
+    static VRCSceneTemplateInitializer()
+    {
+        // runs a single time when the project is launched
+        bool hasRun = SessionState.GetBool(HasRunStateKey, false);
+        if (!hasRun)
+        {
+            SessionState.SetBool(HasRunStateKey, true);
+
+            // wait a tick to ensure the editor allows scene editing
+            EditorApplication.delayCall += () =>
+            {
+                // init default scene if there are no other scene assets
+                if (AssetDatabase.FindAssets("t:Scene", new[] { "Assets" }).Length == 0)
+                {
+                    var template = (SceneTemplateAsset)AssetDatabase.LoadAssetAtPath(SceneTemplatePath, typeof(SceneTemplateAsset));
+                    if (template != null)
+                    {
+                        var result = SceneTemplateService.Instantiate(template, false, ScenePath);
+                        Debug.Log($"Initialized {result.sceneAsset.name}");
+                    }
+                    else
+                    {
+                        Debug.LogError($"Failed to initialize VRChat default world scene because the file does not exist or is inaccessible: {SceneTemplatePath}");
+                    }
+                }
+            };
+        }
+    }
+}