From 5e12d1d6f6c4864d019425f9aaa3ab24720028a7 Mon Sep 17 00:00:00 2001
From: Reina_Sakiria <rs@rs64.net>
Date: Sun, 17 Nov 2024 17:46:19 +0900
Subject: [PATCH] fix: Forget to keep the inverse root bone.

---
 Editor/MeshSettingsPass.cs | 57 +++++++++++++++++++++++++++++++++++---
 1 file changed, 53 insertions(+), 4 deletions(-)

diff --git a/Editor/MeshSettingsPass.cs b/Editor/MeshSettingsPass.cs
index 4382fc07..2a414116 100644
--- a/Editor/MeshSettingsPass.cs
+++ b/Editor/MeshSettingsPass.cs
@@ -1,4 +1,5 @@
-using System.Linq;
+using System.Collections.Generic;
+using System.Linq;
 using UnityEngine;
 
 namespace nadena.dev.modular_avatar.core.editor
@@ -144,9 +145,57 @@ namespace nadena.dev.modular_avatar.core.editor
 
                     if (newMesh) context.SaveAsset(newMesh);
                 }
-                smr.rootBone = settings.RootBone;
-                smr.localBounds = settings.Bounds;
+
+                var settingsRootBone = settings.RootBone;
+                settingsRootBone = settingsRootBone == null ? smr.transform : settingsRootBone;
+                var smrRootBone = smr.rootBone;
+                smrRootBone = smrRootBone == null ? smr.transform : smrRootBone;
+
+                if (IsInverted(smrRootBone) != IsInverted(settingsRootBone))
+                {
+                    smr.rootBone = GetInvertedRootBone(settingsRootBone);
+
+                    var bounds = settings.Bounds;
+                    var center = bounds.center;
+                    center.x *= -1;
+                    bounds.center = center;
+                    smr.localBounds = bounds;
+                }
+                else
+                {
+                    smr.rootBone = settings.RootBone;
+                    smr.localBounds = settings.Bounds;
+                }
             }
         }
+
+        private bool IsInverted(Transform bone)
+        {
+            var inverseCount = 0;
+
+            var scale = bone.lossyScale;
+            if (scale.x < 0) inverseCount += 1;
+            if (scale.y < 0) inverseCount += 1;
+            if (scale.z < 0) inverseCount += 1;
+
+            return (inverseCount % 2) != 0;
+        }
+        private Dictionary<Transform, Transform> invertedRootBoneCache = new();
+        private Transform GetInvertedRootBone(Transform rootBone)
+        {
+            if (invertedRootBoneCache.TryGetValue(rootBone, out var cache)) { return cache; }
+
+            var cloned = Object.Instantiate(rootBone.gameObject);
+            cloned.name = rootBone.gameObject.name + "-InvertedRootBone";
+            cloned.transform.SetParent(rootBone, false);
+
+            var invertedRootBone = cloned.transform;
+            var scale = invertedRootBone.localScale;
+            scale.x *= -1;
+            invertedRootBone.localScale = scale;
+
+            invertedRootBoneCache[rootBone] = invertedRootBone;
+            return invertedRootBone;
+        }
     }
-}
\ No newline at end of file
+}