ProjectDDD/Packages/SLUnity/Editor/Tools/AnimatorUtil.cs

using System.Collections.Generic;
using UnityEditor;
using UnityEditor.Animations;
using UnityEngine;

namespace SLUnityEditor.Tools
{
    public class AnimatorUtil
    {
        [MenuItem("Assets/Nest AnimationClips in Controller", true)]
        public static bool NestAnimClipsValidate() => Selection.activeObject != null && Selection.activeObject.GetType() == typeof(AnimatorController);

        [MenuItem("Assets/Nest AnimationClips in Controller")]
        public static void NestAnimClips()
        {
            var anim_controller = (AnimatorController)Selection.activeObject;
            if (anim_controller == null) return;

            // Get all objects currently in Controller asset, we'll destroy them later
            var objects = AssetDatabase.LoadAllAssetsAtPath(AssetDatabase.GetAssetPath(anim_controller));

            AssetDatabase.SaveAssets();

            // Add animations from all animation layers, without duplicating them
            var oldToNew = new Dictionary<AnimationClip, AnimationClip>();
            foreach (var layer in anim_controller.layers)
            {
                foreach (var state in layer.stateMachine.states)
                {
                    var old = state.state.motion as AnimationClip;
                    if (old == null) continue;

                    if (!oldToNew.ContainsKey(old))    // New animation in list - create new instance
                    {
                        var newClip = UnityEngine.Object.Instantiate(old) as AnimationClip;
                        newClip.name = old.name;
                        AssetDatabase.AddObjectToAsset(newClip, anim_controller);
                        AssetDatabase.ImportAsset(AssetDatabase.GetAssetPath(newClip));
                        oldToNew[old] = newClip;
                        Debug.Log("Nested animation clip: " + newClip.name);
                    }

                    state.state.motion = oldToNew[old];
                }
            }

            // Destroy all old AnimationClips in asset
            for (var i = 0; i < objects.Length; i++)
            {
                if (objects[i].GetType() == typeof(AnimationClip))
                {
                    UnityEngine.Object.DestroyImmediate(objects[i], true);
                }
            }
            AssetDatabase.SaveAssets();
        }
    }
}