Fix the Quaternius side swap, arm swing axis, and hand-proxy position (backward-compatible)

src/game/npc_avatar.gd

@@ -420,27 +420,31 @@ func _build_skinned_body(npc_type: int) -> bool:
 	_rig.add_child(_head)
 	for side in [-1.0, 1.0]:
 		var suffix := "L" if side < 0.0 else "R"
+		# The Quaternius rig labels its joints with the opposite side (its "L" sits
+		# at +x while the project's "L" sits at −x), so the dot-suffixed names are
+		# looked up with a swapped suffix.
+		var qsuffix := "R" if side < 0.0 else "L"
 		var hip := Node3D.new()
 		hip.name = "Hip" + suffix
-		hip.position = _rest_origin(["Hip" + suffix, "UpperLeg." + suffix])
+		hip.position = _rest_origin(["Hip" + suffix, "UpperLeg." + qsuffix])
 		_rig.add_child(hip)
 		var knee := Node3D.new()
 		knee.name = "Knee"
-		knee.position = _rest_origin(["Knee" + suffix, "LowerLeg." + suffix]) - hip.position
+		knee.position = _rest_origin(["Knee" + suffix, "LowerLeg." + qsuffix]) - hip.position
 		hip.add_child(knee)
 		_legs.append(hip)
 		_knees.append(knee)
 		var shoulder := Node3D.new()
 		shoulder.name = "Shoulder" + suffix
-		shoulder.position = _rest_origin(["Shoulder" + suffix, "UpperArm." + suffix])
+		shoulder.position = _rest_origin(["Shoulder" + suffix, "UpperArm." + qsuffix])
 		_rig.add_child(shoulder)
 		var elbow := Node3D.new()
 		elbow.name = "Elbow"
-		elbow.position = _rest_origin(["Elbow" + suffix, "LowerArm." + suffix]) - shoulder.position
+		elbow.position = _rest_origin(["Elbow" + suffix, "LowerArm." + qsuffix]) - shoulder.position
 		shoulder.add_child(elbow)
 		var hand := Node3D.new()
 		hand.name = "Hand"
-		hand.position = _rest_origin(["Hand" + suffix, "Wrist." + suffix]) - elbow.position
+		hand.position = _rest_origin(["Hand" + suffix, "Wrist." + qsuffix]) - _rest_origin(["Elbow" + suffix, "LowerArm." + qsuffix])
 		elbow.add_child(hand)
 		_arms.append(shoulder)
 		_elbows.append(elbow)
@@ -514,21 +518,21 @@ func _sync_skeleton() -> void:
 	if _skeleton == null or _bone_indices.is_empty():
 		return
 	for i in 2:
-		_pose_bone_any(["UpperLeg.L", "HipL"], ["UpperLeg.R", "HipR"], i, _legs[i].rotation.x)
+		_pose_bone_any(["UpperLeg.R", "HipL"], ["UpperLeg.L", "HipR"], i, _legs[i].rotation.x)
 	for i in 2:
-		_pose_bone_any(["LowerLeg.L", "KneeL"], ["LowerLeg.R", "KneeR"], i, _knees[i].rotation.x)
+		_pose_bone_any(["LowerLeg.R", "KneeL"], ["LowerLeg.L", "KneeR"], i, _knees[i].rotation.x)
 	for i in 2:
-		_pose_bone_any(["UpperArm.L", "ShoulderL"], ["UpperArm.R", "ShoulderR"], i, _arms[i].rotation.x)
+		_pose_bone_any(["UpperArm.R", "ShoulderL"], ["UpperArm.L", "ShoulderR"], i, _arms[i].rotation.x, Vector3.LEFT)
 	for i in 2:
-		_pose_bone_any(["LowerArm.L", "ElbowL"], ["LowerArm.R", "ElbowR"], i, _elbows[i].rotation.x)
+		_pose_bone_any(["LowerArm.R", "ElbowL"], ["LowerArm.L", "ElbowR"], i, _elbows[i].rotation.x, Vector3.LEFT)
 	if _head != null:
 		_pose_bone("Head", _head.rotation.y, Vector3.UP)
 
-func _pose_bone_any(left: Array, right: Array, index: int, angle: float) -> void:
+func _pose_bone_any(left: Array, right: Array, index: int, angle: float, axis: Vector3 = Vector3.RIGHT) -> void:
 	var names: Array = left if index == 0 else right
 	for bone_name in names:
 		if _bone_indices.has(bone_name):
-			_pose_bone(bone_name, angle, Vector3.RIGHT)
+			_pose_bone(bone_name, angle, axis)
 			return
 
 func _pose_bone(bone_name: String, angle: float, axis: Vector3) -> void: