Preserve local transform when rebinding humanoid avatar

Editor/PluginDefinition/PluginDefinition.cs

@@ -81,19 +81,7 @@ namespace nadena.dev.modular_avatar.core.editor.plugin
                     FixupExpressionsMenuPass.FixupExpressionsMenu(maContext);
                 });
 #endif
-                seq.Run("Rebind humanoid avatar", ctx =>
-                {
-                    // workaround problem with avatar matching
-                    // https://github.com/bdunderscore/modular-avatar/issues/430
-                    var animator = ctx.AvatarRootObject.GetComponent<Animator>();
-                    if (animator)
-                    {
-                        var avatar = animator.avatar;
-                        animator.avatar = null;
-                        // ReSharper disable once Unity.InefficientPropertyAccess
-                        animator.avatar = avatar;
-                    }
-                });
+                seq.Run(RebindHumanoidAvatarPass.Instance);
                 seq.Run("Purge ModularAvatar components", ctx =>
                 {
                     foreach (var component in ctx.AvatarRootTransform.GetComponentsInChildren<AvatarTagComponent>(true))
@@ -253,6 +241,14 @@ namespace nadena.dev.modular_avatar.core.editor.plugin
     }
 #endif
 
+    class RebindHumanoidAvatarPass : MAPass<RebindHumanoidAvatarPass>
+    {
+        protected override void Execute(ndmf.BuildContext context)
+        {
+            new RebindHumanoidAvatar(context).Process();
+        }
+    }
+
     class GCGameObjectsPluginPass : MAPass<GCGameObjectsPluginPass>
     {
         protected override void Execute(ndmf.BuildContext context)

Editor/RebindHumanoidAvatar.cs

@@ -0,0 +1,68 @@
+using System.Linq;
+using UnityEngine;
+
+namespace nadena.dev.modular_avatar.core.editor.plugin
+{
+    // workaround problem with avatar matching
+    // https://github.com/bdunderscore/modular-avatar/issues/430
+    internal class RebindHumanoidAvatar
+    {
+        private readonly ndmf.BuildContext _buildContext;
+
+        public RebindHumanoidAvatar(ndmf.BuildContext context)
+        {
+            _buildContext = context;
+        }
+
+        public void Process()
+        {
+            var avatarAnimator = _buildContext.AvatarRootObject.GetComponent<Animator>();
+            if (avatarAnimator == null) return;
+
+            var localTransformValues = _buildContext.AvatarRootObject
+                .GetComponentsInChildren<Transform>(true)
+                .ToDictionary((t) => t, LocalTransformValue.FromTransform);
+
+            var boundAvatar = avatarAnimator.avatar;
+            avatarAnimator.avatar = null;
+            // ReSharper disable once Unity.InefficientPropertyAccess
+            avatarAnimator.avatar = boundAvatar;
+
+            // resetting avatar also resets local transform value from avatar asset
+            // needs to restore them manually from pre-cache
+            // https://github.com/bdunderscore/modular-avatar/issues/1036
+            for (var bone = HumanBodyBones.Hips; bone < HumanBodyBones.LastBone; ++bone)
+            {
+                var boneTransform = avatarAnimator.GetBoneTransform(bone);
+                if (boneTransform == null) continue;
+                if (localTransformValues.TryGetValue(boneTransform, out var preserved))
+                {
+                    preserved.RestoreToTransform(boneTransform);
+                }
+            }
+        }
+
+        struct LocalTransformValue
+        {
+            Vector3 Position;
+            Quaternion Rotation;
+            Vector3 Scale;
+
+            internal static LocalTransformValue FromTransform(Transform t)
+            {
+                return new LocalTransformValue
+                {
+                    Position = t.localPosition,
+                    Rotation = t.localRotation,
+                    Scale = t.localScale
+                };
+            }
+
+            internal readonly void RestoreToTransform(Transform t)
+            {
+                t.SetLocalPositionAndRotation(Position, Rotation);
+                t.localScale = Scale;
+            }
+        }
+    }
+}

Editor/RebindHumanoidAvatar.cs.meta

@@ -0,0 +1,11 @@
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