Moving/copying blend tree nodes, 'raising' the root of a blend tree

Not a solution, but the closest thing I can think of is writing an editor script to change the data in an AnimatorController. https://docs.unity3d.com/ScriptReference/Animations.AnimatorController.CreateBlendTreeInController.html

As you can see, there are methods to write blend trees into an animator controller, though I'm not sure I see any way to read from them... I'll look deeper.

...

Yep! You can get a "motion" for a state. https://docs.unity3d.com/ScriptReference/Animations.AnimatorController.GetStateEffectiveMotion.html

And since blend trees inherit from motions, you'll just have to do a type check to see if you then have a blend tree. https://docs.unity3d.com/ScriptReference/Animations.BlendTree.html

And then, I don't really see any way to surgically replace that blend tree without having to copy out the entire layer's contents, and re-create it all again. https://docs.unity3d.com/ScriptReference/Animations.AnimatorController.RemoveLayer.html

So, principally, it's possible to copy out all the layer info, target the blend tree data you want to edit, stuff, then reconstruct the layer. But that sounds like at least a week of quite tough work even for an experienced dev when you factor in all the UI you'd have to do. Yikes.

Sorry that I don't have an answer, but, yeah, I would very much like someone else to make it easy to move blend tree nodes around.

I found this on another thread, asking similar question with slightly different wording. so pasting this here too since it helped me. i gives an error, but it makes the blend tree asset and one can then use this in a tree slot, allowing you to "make a parent"

 using UnityEditor;
 using UnityEngine;
 using UnityEditor.Animations;
  
 public class CreateBlendtreeAsset : MonoBehaviour {
  
 [MenuItem("AnimTools/GameObject/Asset from Blendtree")]
 static void CreateBlendtree()
 {
 string path = "Assets/";
  
 string currentPath = AssetDatabase.GetAssetPath(Selection.activeObject);
 if (currentPath != null)
 {
 path = currentPath;
 }
  
 BlendTree BT = Selection.activeObject as BlendTree;
  
 BlendTree BTcopy = Instantiate<BlendTree>(BT);
  
 AssetDatabase.CreateAsset(BTcopy, AssetDatabase.GenerateUniqueAssetPath(path + "_" + BT.name + ".asset"));
 }
 }

so put this in some (any) folder named "editor", it makes a menu to the top bar called animTools

found in https://forum.unity.com/threads/mecanim-blend-trees-copy-and-paste.180152/ posted by hareklas. the post also had some longer scripts, but this short one worked for me and didn't try the longer ones, maybe those help some too

Sorry that I don't have an answer, but, yeah, I would very much like someone else to make it easy to move blend tree nodes around.

It just so happens that is exactly what I did :) https://assetstore.unity.com/packages/tools/animation/anim-tree-editor-161217

My editor extension adds a tree view window that displays the entire contents of an animator controller and allows you to drag/drop and reorganize blend trees. It supports adding, duplicating, and disconnecting blend trees.

Saving blend trees as assets has some pretty serious issues, the unity editor isn't really setup to support that in all cases.

From the same thread that l3xxx above found that script, another response has been added, with a super simple editor script that lets you simply copy/paste trees:

https://forum.unity.com/threads/mecanim-blend-trees-copy-and-paste.180152/#post-5989277

So if your current setup is like this: BlendTreeA -> motions

And you want a setup like this: BlendTreeB -> BlendTreeA -> motions

Then first select BlendTreeA, and copy it using the new menu option. Then create a new blank setup if you need to, that has BlendTreeB -> New Blend Tree, and then go into New Blend Tree (i.e. the nested one), then use the menu to paste.

 using UnityEditor;
 using UnityEngine;
 using UnityEditor.Animations;
 using System.IO;
 
 public class CreateBlendTreeAsset
 {
     [MenuItem("Assets/Create/Animation Blend Tree", priority = 402)]
     private static void CreateBlendTree()
     {
         var directory = GetSelectedDirectory();
         var asset = new BlendTree();
         var path = Path.Combine(directory, "New Blend Tree.asset");
         // display immedate rename prompt in the project window
         ProjectWindowUtil.CreateAsset(asset, path);
     }
 
     private static string GetSelectedDirectory()
     {
         var activeObject = Selection.activeObject;
         if (activeObject == null)
         { // nothing is selected in the project window
             return "Assets";
         }
 
         var activePath = AssetDatabase.GetAssetPath(activeObject);
         if (activeObject is DefaultAsset)
         { // a folder is selected in the project window
             return activePath;
         }
 
         // an asset is selected in the project window
         return Path.GetDirectoryName(activePath);
     }
 }