From c3338d3881d413589d7e316eb867a3cb0eb2d7c0 Mon Sep 17 00:00:00 2001
From: ousttrue <ousttrue@gmail.com>
Date: Wed, 9 Apr 2025 15:11:04 +0900
Subject: [PATCH] Avoid resetting indexmaps causing exceptions

---
 .../VRM/Runtime/SpringBone/Logic/SpringBoneSystem.cs   | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Assets/VRM/Runtime/SpringBone/Logic/SpringBoneSystem.cs b/Assets/VRM/Runtime/SpringBone/Logic/SpringBoneSystem.cs
index a44091bf1..4942a4c11 100644
--- a/Assets/VRM/Runtime/SpringBone/Logic/SpringBoneSystem.cs
+++ b/Assets/VRM/Runtime/SpringBone/Logic/SpringBoneSystem.cs
@@ -38,7 +38,15 @@ namespace VRM.SpringBone
 
             for (int i = 0; i < m_joints.Count; ++i)
             {
-                m_jointIndexMap.Add(m_joints[i].Item1, i);
+                // #2617
+                // Keys may not be unique
+                m_jointIndexMap[m_joints[i].Item1] = i;
+
+                // this index refer m_joints
+                // if not unique,
+                // m_joints[] = { (a, a_state), (b, b_state), (a, a_state) ... };
+                // m_joints[0] and m_joints[2] is same.
+                // The above code is ok
             }
         }