Add legacy animation creator

Author: mousedoc

Assets/Scripts/Editor/Animation.meta

@@ -0,0 +1,28 @@
+using System.IO;
+using UnityEditor;
+using UnityEngine;
+
+public class LegacyAnimationCreator
+{
+    [MenuItem("Assets/Create/Legacy Animation", priority = 402)]
+    public static void CompressSelectedAnimationClips()
+    {
+        var clip = new AnimationClip();
+        clip.legacy = true;
+        clip.name = "New Legacy Animation";
+
+        string path;
+        var selection = Selection.activeObject;
+        if (selection == null)
+            path = "Assets";
+        else
+            path = AssetDatabase.GetAssetPath(selection.GetInstanceID());
+
+        path = Path.GetDirectoryName(path);
+        path += $"/{clip.name}.anim";
+
+        ProjectWindowUtil.CreateAsset(clip, path);
+        Selection.activeObject = clip;
+        EditorUtility.SetDirty(clip);
+    }
+}