fix: workaround issues with double-Armature hack (#436)

fixes: #308

Assets/_ModularAvatar/EditModeTests/AvatarObjectReferenceTest.cs

@@ -0,0 +1,21 @@
+using modular_avatar_tests;
+using nadena.dev.modular_avatar.core;
+using NUnit.Framework;
+
+public class AvatarObjectReferenceTest : TestBase
+{
+    [Test]
+    public void whenFakeArmaturePresent_bindsToRealArmature()
+    {
+        var root = CreateRoot("root");
+        var fake_armature = CreateChild(root, "Armature");
+        var real_armature = CreateChild(root, "Armature");
+        
+        var hips = CreateChild(real_armature, "Hips");
+
+        var reference = new AvatarObjectReference();
+        reference.referencePath = "Armature";
+        
+        Assert.AreEqual(real_armature, reference.Get(root.transform));
+    }
+}

Assets/_ModularAvatar/EditModeTests/AvatarObjectReferenceTest.cs.meta

@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: bb23d6c06929440e999c855d3b9f70fc
+timeCreated: 1694775902

Assets/_ModularAvatar/EditModeTests/GameObjectGC/GameObjectGC.cs

@@ -1,4 +1,5 @@
-using modular_avatar_tests;
+using System.Linq;
+using modular_avatar_tests;
 using nadena.dev.modular_avatar.core.editor;
 using NUnit.Framework;
 using UnityEngine;
@@ -38,4 +39,22 @@ public class GameObjectGC : TestBase
         Assert.True(bone2 != null);
         Assert.True(bone3 == null);
     }
+
+    [Test]
+    public void RetainArmatureHack()
+    {
+        var fake_humanoid = CreatePrefab("FakeHumanoid.prefab");
+        var avdesc = fake_humanoid.GetComponent<VRCAvatarDescriptor>();
+
+        var armature = new GameObject();
+        armature.name = "Armature";
+        armature.transform.parent = fake_humanoid.transform;
+        armature.transform.SetSiblingIndex(0);
+        
+        new GCGameObjectsPass(new BuildContext(avdesc), fake_humanoid).OnPreprocessAvatar();
+        AvatarProcessor.ProcessAvatar(fake_humanoid);
+
+        Assert.AreEqual(2,
+            avdesc.GetComponentsInChildren<Transform>().Count(t => t.gameObject.name == "Armature"));
+    }
 }

Packages/nadena.dev.modular-avatar/Editor/OptimizationPasses/GCGameObjectsPass.cs

@@ -99,6 +99,28 @@ namespace nadena.dev.modular_avatar.core.editor
                     MarkObject(t.gameObject);
                 }
             }
+            
+            // https://github.com/bdunderscore/modular-avatar/issues/308
+            // If we have duplicate Armature bones, retain them all in order to deal with some horrible hacks that are
+            // in use in the wild.
+            try
+            {
+                var trueArmature = animator?.GetBoneTransform(HumanBodyBones.Hips)?.parent;
+                if (trueArmature != null)
+                {
+                    foreach (Transform t in _root.transform)
+                    {
+                        if (t.name == trueArmature.name)
+                        {
+                            MarkObject(t.gameObject);
+                        }
+                    }
+                }
+            }
+            catch (MissingComponentException e)
+            {
+                // No animator? weird. Move on.
+            }
         }
 
         private void MarkPhysBone(VRCPhysBone pb)

Packages/nadena.dev.modular-avatar/Runtime/AvatarObjectReference.cs

@@ -39,7 +39,27 @@ namespace nadena.dev.modular_avatar.core
                 return _cachedReference;
             }
 
-            return (_cachedReference = avatar.transform.Find(referencePath)?.gameObject);
+            _cachedReference = avatar.transform.Find(referencePath)?.gameObject;
+            if (_cachedReference == null) return null;
+            
+            // https://github.com/bdunderscore/modular-avatar/issues/308
+            // Some avatars have multiple "Armature" objects in order to confuse VRChat into changing the avatar eye
+            // position. We need to be smarter than VRChat and find the "true" armature in this case.
+            var targetName = _cachedReference.name;
+            var parent = _cachedReference.transform.parent;
+            if (targetName == "Armature" && parent != null && _cachedReference.transform.childCount == 0)
+            {
+                foreach (Transform possibleTarget in parent)
+                {
+                    if (possibleTarget.gameObject.name == targetName && possibleTarget.childCount > 0)
+                    {
+                        _cachedReference = possibleTarget.gameObject;
+                        break;
+                    }
+                }
+            }
+
+            return _cachedReference;
         }
 
         public void Set(GameObject target)