Made GLTF importer consistent with FBX importer and implemented proper support for root motion.

Editor/Scripts/GLTFImporter.cs

@@ -107,6 +107,7 @@ private static void EnsureShadersAreLoaded()
         [SerializeField] internal CameraImportOption _importCamera = CameraImportOption.ImportAndCameraDisabled;
         [SerializeField] internal AnimationMethod _importAnimations = AnimationMethod.Mecanim;
         [SerializeField] internal bool _mecanimHumanoidFlip = false;
+        [SerializeField] internal string _nonHumanoidRootNodeName;
         [SerializeField] internal bool _addAnimatorComponent = false;
         [SerializeField] internal bool _animationLoopTime = true;
         [SerializeField] internal bool _animationLoopPose = false;
@@ -550,11 +551,17 @@ string GetUniqueName(string desiredName)
 	            //     }
                 // }
 
-                if (gltfScene && _importAnimations == AnimationMethod.MecanimHumanoid)
+                if (gltfScene)
                 {
-	                var avatar = HumanoidSetup.AddAvatarToGameObject(gltfScene, _mecanimHumanoidFlip);
-	                if (avatar)
-						ctx.AddObjectToAsset("avatar", avatar);
+                    Avatar avatar = null;
+
+                    if (_importAnimations == AnimationMethod.MecanimHumanoid)
+                        avatar = HumanoidSetup.AddAvatarToGameObject(gltfScene, _mecanimHumanoidFlip);
+                    else if (_importAnimations == AnimationMethod.Mecanim)
+                        avatar = NonHumanoidSetup.AddAvatarToGameObject(gltfScene, false, _nonHumanoidRootNodeName);
+
+                    if (avatar)
+                        ctx.AddObjectToAsset("avatar", avatar);
                 }
 
                 var renderers = gltfScene ? gltfScene.GetComponentsInChildren<Renderer>(true) : Array.Empty<Renderer>();
@@ -946,6 +953,7 @@ private void CreateGLTFScene(GLTFImportContext context, out GameObject scene,
 		    {
 			    DataLoader = new FileLoader(Path.GetDirectoryName(projectFilePath)),
 			    AnimationMethod = _importAnimations,
+                NonHumanoidRootNodeName = _nonHumanoidRootNodeName,
 			    AnimationLoopTime = _animationLoopTime,
 			    AnimationLoopPose = _animationLoopPose,
 			    ImportContext = context,

Editor/Scripts/GLTFImporterInspector.cs

@@ -164,6 +164,14 @@ private void AnimationInspectorGUI()
 				EditorGUILayout.PropertyField(flip, new GUIContent("Flip Forward", "Some formats like VRM have a different forward direction for Avatars. Enable this option if the animation looks inverted."));
 				EditorGUI.indentLevel--;
 			}
+            else if (animationMethod.enumValueIndex == (int)AnimationMethod.Mecanim)
+            {
+                var rootNodeName = serializedObject.FindProperty(nameof(GLTFImporter._nonHumanoidRootNodeName));
+                EditorGUI.indentLevel++;
+                EditorGUILayout.PropertyField(rootNodeName, new GUIContent("Root Node Name", "Transform name of the root motion transform. If empty no root motion is defined and you must take care of avatar movement yourself."));
+                EditorGUILayout.HelpBox("Enter just the name of the root node; not its path in hierarchy.", MessageType.Info);
+                EditorGUI.indentLevel--;
+            }
 			if (hasAnimationData && anim.enumValueIndex > 0)
 			{
 				var loopTime = serializedObject.FindProperty(nameof(GLTFImporter._animationLoopTime));

Editor/Scripts/Internal/HumanoidSetup.cs

@@ -106,4 +106,31 @@ static void _OpenEditor(MenuCommand command)
 	    }
 #endif
 	}
+
+    //todo: XtroTheArctic: I don't know how to add a new script file to a local package. We can fix this during PR phase.
+    internal static class NonHumanoidSetup
+    {
+        internal static Avatar AddAvatarToGameObject(GameObject gameObject, bool flipForward, string RootNode)
+        {
+            var previousRotation = gameObject.transform.rotation;
+            if (flipForward)
+                gameObject.transform.rotation *= Quaternion.Euler(0, 180, 0);
+
+            Avatar avatar = AvatarBuilder.BuildGenericAvatar(gameObject, RootNode);
+            avatar.name = gameObject.name + "Avatar";
+
+            if (flipForward)
+                gameObject.transform.rotation = previousRotation;
+
+            if (!avatar.isValid || avatar.isHuman)
+            {
+                Object.DestroyImmediate(avatar);
+                return null;
+            }
+
+            var animator = gameObject.GetComponent<Animator>();
+            if (animator) animator.avatar = avatar;
+            return avatar;
+        }
+    }
 }

Runtime/Scripts/GLTFSceneImporter.cs

@@ -52,6 +52,7 @@ public class ImportOptions
 		public AsyncCoroutineHelper AsyncCoroutineHelper = null;
 		public bool ThrowOnLowMemory = true;
 		public AnimationMethod AnimationMethod = AnimationMethod.Legacy;
+        public string NonHumanoidRootNodeName;
 		public bool AnimationLoopTime = true;
 		public bool AnimationLoopPose = false;
 		public DeduplicateOptions DeduplicateResources = DeduplicateOptions.None;
@@ -1392,7 +1393,7 @@ protected virtual async Task ConstructScene(GLTFScene scene, bool showSceneObj,
 					}
 				}
 
-				if (_options.AnimationMethod == AnimationMethod.MecanimHumanoid)
+				if (_options.AnimationMethod == AnimationMethod.MecanimHumanoid || _options.AnimationMethod == AnimationMethod.Mecanim && !string.IsNullOrEmpty(_options.NonHumanoidRootNodeName))
                 {
                     var animator = sceneObj.GetComponent<Animator>();
                     if (!animator) animator = sceneObj.AddComponent<Animator>();