From f8b1fce6e5c087787afcaf059555f902043ae7cc Mon Sep 17 00:00:00 2001
From: Sylvester Kaczmarek
 <16242628+sylvesterkaczmarek@users.noreply.github.com>
Date: Mon, 24 Aug 2026 02:37:48 +0100
Subject: [PATCH] Serialize Unity hinge reference with invariant culture

---
 unity/Runtime/Components/Joints/MjHingeJoint.cs    |  2 +-
 .../Editor/Components/Joints/MjHingeJointTests.cs  | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/unity/Runtime/Components/Joints/MjHingeJoint.cs b/unity/Runtime/Components/Joints/MjHingeJoint.cs
index 08e5958b1b0..cded0d4aa20 100644
--- a/unity/Runtime/Components/Joints/MjHingeJoint.cs
+++ b/unity/Runtime/Components/Joints/MjHingeJoint.cs
@@ -91,7 +91,7 @@ protected override XmlElement OnGenerateMjcf(XmlDocument doc) {
         throw new ArgumentException("Lower range value can't be bigger than Higher");
       }
       mjcf.SetAttribute("range", MjEngineTool.MakeLocaleInvariant($"{RangeLower} {RangeUpper}"));
-      mjcf.SetAttribute("ref", $"{Configuration}");
+      mjcf.SetAttribute("ref", MjEngineTool.MakeLocaleInvariant($"{Configuration}"));
 
       return mjcf;
     }
diff --git a/unity/Tests/Editor/Components/Joints/MjHingeJointTests.cs b/unity/Tests/Editor/Components/Joints/MjHingeJointTests.cs
index cff7529373a..9b785c27b6d 100644
--- a/unity/Tests/Editor/Components/Joints/MjHingeJointTests.cs
+++ b/unity/Tests/Editor/Components/Joints/MjHingeJointTests.cs
@@ -15,6 +15,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Xml;
 using NUnit.Framework;
 using UnityEngine;
@@ -68,6 +69,19 @@ public void GenerateLimits() {
     Assert.That(_doc.OuterXml, Does.Contain(@"range=""-20 10"""));
   }
 
+  [Test]
+  public void GenerateReferenceUsesInvariantCulture() {
+    var previousCulture = CultureInfo.CurrentCulture;
+    CultureInfo.CurrentCulture = new CultureInfo("fr-FR");
+    try {
+      _joint.Configuration = 1.5f;
+      var element = _joint.GenerateMjcf("name", _doc);
+      Assert.That(element.GetAttribute("ref"), Is.EqualTo("1.5"));
+    } finally {
+      CultureInfo.CurrentCulture = previousCulture;
+    }
+  }
+
   [Test]
   public void ParsingPosition() {
     var jointElement = (XmlElement)_doc.AppendChild(_doc.CreateElement("joint"));