From c2ea844f0c244bbf6d2de135d4e0f42f2d52f702 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 4 Mar 2026 03:33:25 +0000
Subject: [PATCH] Fix StateRootNodeIndex mapping: use (Count - 1 - index) for
 reverse ChildProperties order

Co-authored-by: LoogLong <86428208+LoogLong@users.noreply.github.com>
---
 FModel/ViewModels/AnimGraphViewModel.cs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/FModel/ViewModels/AnimGraphViewModel.cs b/FModel/ViewModels/AnimGraphViewModel.cs
index 2040cc10..7228a49e 100644
--- a/FModel/ViewModels/AnimGraphViewModel.cs
+++ b/FModel/ViewModels/AnimGraphViewModel.cs
@@ -653,6 +653,8 @@ public class AnimGraphViewModel
                     metadata.StateNames.Add(stateName);
 
                     // Mark root node via StateRootNodeIndex
+                    // UE stores node indices in reverse order relative to ChildProperties,
+                    // so the actual index into animNodeProps is (Count - 1 - stateRootIndex).
                     if (!stateStruct.TryGetValue(out int stateRootIndex, "StateRootNodeIndex") ||
                         stateRootIndex < 0 || stateRootIndex >= animNodeProps.Count)
                     {
@@ -660,7 +662,8 @@ public class AnimGraphViewModel
                         continue;
                     }
 
-                    var rootPropName = animNodeProps[stateRootIndex].name;
+                    var mappedIndex = animNodeProps.Count - 1 - stateRootIndex;
+                    var rootPropName = animNodeProps[mappedIndex].name;
                     metadata.StateRootPropNames.Add(rootPropName);
                     if (nodeByName.TryGetValue(rootPropName, out var rootNode))
                         rootNode.AdditionalProperties["BelongsToStateMachine"] = machineName;