scripts/avatar/avatar_catalog.gd

@@ -0,0 +1,173 @@
+## AvatarCatalog - Asset catalog management.
+##
+## Manages the mapping of asset IDs to their metadata and resource paths.
+## Loads the catalog manifest from disk and provides lookup by ID and slot.
+##
+## The catalog is loaded from `res://assets/avatars/catalog.json` which follows
+## the format specified in avatar.md §7.2.
+
+class_name AvatarCatalog
+extends RefCounted
+
+
+## Emitted when the catalog is loaded successfully.
+signal catalog_loaded
+
+## Emitted when the catalog fails to load.
+signal catalog_load_failed(error_message: String)
+
+## Catalog manifest structure:
+## { "assets": { "id": { "type", "slot", "path", "version", ... } } }
+var _catalog: Dictionary = {}
+var _loaded: bool = false
+var _catalog_path: String = "res://assets/avatars/catalog.json"
+
+
+# ---------------------------------------------------------------------------
+# Public API
+# ---------------------------------------------------------------------------
+
+## Load the catalog from disk. Call this before any lookups.
+func load_catalog(path: String = _catalog_path) -> Error:
+	_catalog_path = path
+	_catalog = {}
+
+	var file = FileAccess.open(path, FileAccess.READ)
+	if file == null:
+		var err = FileAccess.get_open_error()
+		catalog_load_failed.emit("Cannot open catalog: %s (error %d)" % [path, err])
+		return err
+
+	var json_text: String = file.get_as_text()
+	file.close()
+
+	var json: JSONParseResult = JSON.parse_string(json_text)
+	if json == null:
+		catalog_load_failed.emit("Invalid JSON in catalog: %s" % path)
+		return ERR_PARSE_ERROR
+
+	if not json is Dictionary or not json.has("assets"):
+		catalog_load_failed.emit("Catalog missing 'assets' key")
+		return ERR_INVALID_DATA
+
+	_catalog = json["assets"]
+	_loaded = true
+	catalog_loaded.emit()
+	return OK
+
+
+## Get the metadata for an asset by its ID.
+## Returns a Dictionary with keys: type, slot, path, version, etc.
+## Returns null if the asset ID is not found.
+func get_asset(id: String) -> Dictionary:
+	if not _loaded:
+		return {}
+	return _catalog.get(id, {})
+
+
+## Check if an asset ID exists in the catalog.
+func has_asset(id: String) -> bool:
+	if not _loaded:
+		return false
+	return _catalog.has(id)
+
+
+## Get all assets that belong to a given slot.
+## Returns an array of asset ID strings.
+func get_assets_by_slot(slot: String) -> Array[String]:
+	if not _loaded:
+		return []
+	var result: Array[String] = []
+	for id in _catalog:
+		var asset: Dictionary = _catalog[id]
+		if asset.get("slot") == slot:
+			result.append(id)
+	return result
+
+
+## Get all asset IDs in the catalog.
+func get_all_asset_ids() -> Array[String]:
+	if not _loaded:
+		return []
+	return _catalog.keys()
+
+
+## Validate a loadout against the catalog.
+## Returns a Dictionary with "valid" (bool) and "errors" (Array[String]).
+func validate_loadout(loadout: AvatarLoadout) -> Dictionary:
+	var errors: Array[String] = []
+
+	# Check base_body
+	if loadout.base_body.is_empty():
+		errors.append("Loadout missing base_body")
+	elif not has_asset(loadout.base_body):
+		errors.append("Unknown base_body asset: %s" % loadout.base_body)
+	else:
+		var base: Dictionary = get_asset(loadout.base_body)
+		if base.get("type") != "base_body":
+			errors.append("base_body asset '%s' is not type 'base_body'" % loadout.base_body)
+
+	# Check each slot
+	for slot_id in loadout.slots:
+		var slot_value = loadout.slots[slot_id]
+
+		if slot_value == null:
+			continue
+
+		if slot_id == "accessory":
+			# Accessory is an array
+			if not slot_value is Array:
+				errors.append("Slot '%s' must be an array" % slot_id)
+				continue
+			for item_id in slot_value:
+				if not has_asset(item_id):
+					errors.append("Unknown accessory asset: %s" % item_id)
+				else:
+					var asset: Dictionary = get_asset(item_id)
+					if asset.get("slot") != slot_id:
+						errors.append("Accessory '%s' slot '%s' does not match slot '%s'" % [
+							item_id, asset.get("slot"), slot_id
+						])
+		else:
+			# Exclusive slot - single value
+			if not slot_value is String:
+				errors.append("Slot '%s' must be a string or null" % slot_id)
+				continue
+			if not has_asset(slot_value):
+				errors.append("Unknown asset in slot '%s': %s" % [slot_id, slot_value])
+			else:
+				var asset: Dictionary = get_asset(slot_value)
+				if asset.get("slot") != slot_id:
+					errors.append("Asset '%s' slot '%s' does not match slot '%s'" % [
+						slot_value, asset.get("slot"), slot_id
+					])
+
+	return {
+		"valid": errors.is_empty(),
+		"errors": errors
+	}
+
+
+## Compute a hash of the loadout for change detection.
+## Returns a uint32 hash.
+static func compute_loadout_hash(loadout: AvatarLoadout) -> uint32:
+	var hasher = HashingContext.new()
+	hasher.start(HashingContext.HASH_SHA256)
+
+	hasher.update(loadout.base_body.to_utf8_buffer())
+	for slot_id in loadout.slots:
+		var slot_value = loadout.slots[slot_id]
+		hasher.update(slot_id.to_utf8_buffer())
+		if slot_value is Array:
+			for item in slot_value:
+				hasher.update(item.to_utf8_buffer())
+		elif slot_value is String:
+			hasher.update(slot_value.to_utf8_buffer())
+
+	var hash_bytes = hasher.finish()
+	return hash_bytes[0] | (hash_bytes[1] << 8) | (hash_bytes[2] << 16) | (hash_bytes[3] << 24)
+
+
+## Get the catalog path.
+func get_catalog_path() -> String:
+	return _catalog_path

scripts/avatar/avatar_loader.gd

@@ -0,0 +1,561 @@
+## AvatarLoader - glTF/GLB import, skeleton merge, and skin re-targeting.
+##
+## Loads base body and attachment GLB assets, extracts skeletons and meshes,
+## and re-targets attachment skins to the canonical skeleton by bone name.
+##
+## Per the avatar architecture spec (§6.2, §6.3):
+## - The base body carries the canonical skeleton.
+## - Attachments are skinned to the same skeleton by name-based re-targeting.
+## - Static accessories are parented to their mount bone.
+## - Body-part slots hide the corresponding base mesh.
+
+class_name AvatarLoader
+extends Node
+
+
+# ---------------------------------------------------------------------------
+# Constants
+# ---------------------------------------------------------------------------
+
+## Maximum number of attachments allowed in the accessory slot.
+const MAX_ACCESSORY_COUNT := 8
+
+## Skeleton bone names that form the canonical rig (§3.1).
+const CANONICAL_BONES := [
+	"Root",
+	"Hips",
+	"Spine",
+	"Chest",
+	"Neck",
+	"Head",
+	"HeadTop",
+	"Jaw",
+	"LeftEye",
+	"RightEye",
+	"LeftShoulder",
+	"LeftUpperArm",
+	"LeftLowerArm",
+	"LeftHand",
+	"RightShoulder",
+	"RightUpperArm",
+	"RightLowerArm",
+	"RightHand",
+	"LeftUpperLeg",
+	"LeftLowerLeg",
+	"LeftFoot",
+	"RightUpperLeg",
+	"RightLowerLeg",
+	"RightFoot",
+]
+
+
+# ---------------------------------------------------------------------------
+# Signals
+# ---------------------------------------------------------------------------
+
+## Emitted when a base body has been loaded successfully.
+signal base_body_loaded(avatar_node: Node3D)
+
+## Emitted when an attachment has been loaded and merged.
+signal attachment_loaded(slot_id: String, attachment_node: Node3D)
+
+## Emitted on error during loading.
+signal load_error(error_msg: String)
+
+
+# ---------------------------------------------------------------------------
+# State
+# ---------------------------------------------------------------------------
+
+## The fully assembled avatar node (Skeleton3D + meshes + attachments).
+var avatar_node: Node3D = null
+
+## The Skeleton3D belonging to the avatar.
+var skeleton: Skeleton3D = null
+
+## Mapping of bone name -> bone index in the skeleton.
+var _bone_index_map: Dictionary = {}
+
+## Loaded base body meshes, keyed by slot id.
+var _base_meshes: Dictionary = {}
+
+## Loaded attachment nodes, keyed by slot id.
+var _attachments: Dictionary = {}
+
+## Whether the base body has been loaded.
+var is_base_loaded: bool = false
+
+## The avatar catalog reference (set by AvatarSystem).
+var catalog: AvatarCatalog = null
+
+
+# ---------------------------------------------------------------------------
+# Public API
+# ---------------------------------------------------------------------------
+
+## Initialize the loader with a reference to the avatar catalog.
+func init_loader(cat: AvatarCatalog) -> void:
+	catalog = cat
+
+
+## Load the base body asset identified by [param base_body_id].
+## Returns the AvatarNode3D on success, or null on failure.
+func load_base_body(base_body_id: String) -> Node3D:
+	if catalog == null:
+		load_error.emit("AvatarCatalog not set on AvatarLoader")
+		return null
+
+	var asset_meta = catalog.resolve(base_body_id)
+	if asset_meta == null:
+		load_error.emit("Unknown base_body asset: %s" % base_body_id)
+		return null
+
+	if asset_meta.type != "base_body":
+		load_error.emit("Asset '%s' is not a base_body, got '%s'" % [
+			base_body_id, asset_meta.type])
+		return null
+
+	var path: String = asset_meta.path
+	var glb_data: PackedByteArray = _load_file(path)
+	if glb_data.is_empty():
+		load_error.emit("Failed to read GLB file: %s" % path)
+		return null
+
+	avatar_node = _parse_glb_as_avatar(glb_data, path)
+	if avatar_node == null:
+		load_error.emit("Failed to parse GLB: %s" % path)
+		return null
+
+	skeleton = avatar_node.get_node_or_null("Skeleton3D") as Skeleton3D
+	if skeleton == null:
+		load_error.emit("No Skeleton3D found in base body: %s" % path)
+		avatar_node.queue_free()
+		return null
+
+	# Build bone index map for fast lookups.
+	_bone_index_map.clear()
+	for i in skeleton.get_bone_count():
+		var bone_name: String = skeleton.get_bone_name(i)
+		if not bone_name.is_empty():
+			_bone_index_map[bone_name] = i
+
+	# Extract base body meshes and store them.
+	_extract_base_meshes(avatar_node)
+
+	is_base_loaded = true
+	base_body_loaded.emit(avatar_node)
+	return avatar_node
+
+
+## Load and merge an attachment into the avatar.
+## [param slot_id] is the slot to equip into.
+## [param asset_id] is the catalog id of the attachment.
+## Returns the attachment Node3D on success, or null on failure.
+func load_attachment(slot_id: String, asset_id: String) -> Node3D:
+	if not is_base_loaded:
+		load_error.emit("Cannot load attachment: base body not loaded")
+		return null
+
+	if catalog == null:
+		load_error.emit("AvatarCatalog not set on AvatarLoader")
+		return null
+
+	var asset_meta = catalog.resolve(asset_id)
+	if asset_meta == null:
+		load_error.emit("Unknown attachment asset: %s" % asset_id)
+		return null
+
+	if asset_meta.type != "attachment":
+		load_error.emit("Asset '%s' is not an attachment, got '%s'" % [
+			asset_id, asset_meta.type])
+		return null
+
+	# Check slot exclusivity for accessory slot.
+	if slot_id == "accessory":
+		var current_accessories: Array[String] = _attachments.get("accessory", [])
+		if current_accessories.size() >= MAX_ACCESSORY_COUNT:
+			load_error.emit("Accessory slot full (%d/%d)" % [
+				MAX_ACCESSORY_COUNT, MAX_ACCESSORY_COUNT])
+			return null
+
+	var path: String = asset_meta.path
+	var glb_data: PackedByteArray = _load_file(path)
+	if glb_data.is_empty():
+		load_error.emit("Failed to read GLB file: %s" % path)
+		return null
+
+	var attachment_node = _parse_glb_as_attachment(glb_data, path, slot_id)
+	if attachment_node == null:
+		load_error.emit("Failed to parse attachment GLB: %s" % path)
+		return null
+
+	# Retarget skin to the canonical skeleton.
+	_retarget_skin(attachment_node)
+
+	# Parent static accessories to their mount bone.
+	_parent_attachment(attachment_node, slot_id, asset_meta)
+
+	# Store reference.
+	if slot_id == "accessory":
+		var list: Array[String] = _attachments.get("accessory", [])
+		list.append(asset_id)
+		_attachments["accessory"] = list
+	else:
+		_attachments[slot_id] = attachment_node
+
+	attachment_loaded.emit(slot_id, attachment_node)
+	return attachment_node
+
+
+## Remove an attachment from the given slot.
+func unload_attachment(slot_id: String) -> void:
+	if slot_id == "accessory":
+		var list: Array[String] = _attachments.get("accessory", [])
+		for asset_id in list:
+			var node = _attachments.get(asset_id)
+			if node and node is Node:
+				node.queue_free()
+		_attachments.erase("accessory")
+	else:
+		var node = _attachments.get(slot_id)
+		if node and node is Node:
+			node.queue_free()
+		_attachments.erase(slot_id)
+
+
+## Hide or show the base mesh for a given body-part slot.
+func set_base_mesh_visible(slot_id: String, visible: bool) -> void:
+	var mesh = _base_meshes.get(slot_id)
+	if mesh and mesh is Node3D:
+		mesh.visible = visible
+
+
+## Get the current loadout as a dictionary (for serialization).
+func get_current_loadout() -> Dictionary:
+	var loadout: Dictionary = {
+		"base_body": "",
+		"slots": {},
+	}
+
+	# Determine base body id from catalog.
+	if is_base_loaded and catalog != null:
+		# Walk through catalog to find which base_body loaded.
+		for id in catalog.get_all_ids():
+			var meta = catalog.resolve(id)
+			if meta and meta.type == "base_body":
+				loadout.base_body = id
+				break
+
+	# Collect equipped attachments.
+	for slot_id in _attachments:
+		if slot_id == "accessory":
+			loadout.slots[slot_id] = _attachments[slot_id] as Array
+		else:
+			var node = _attachments[slot_id]
+			if node is Node3D:
+				# Find the asset id by matching the node's name.
+				var aid: String = node.name
+				loadout.slots[slot_id] = aid
+
+	return loadout
+
+
+## Reset the avatar to an unloaded state.
+func reset() -> void:
+	if avatar_node and avatar_node is Node:
+		avatar_node.queue_free()
+
+	avatar_node = null
+	skeleton = null
+	_bone_index_map.clear()
+	_base_meshes.clear()
+	_attachments.clear()
+	is_base_loaded = false
+
+
+# ---------------------------------------------------------------------------
+# Internal: GLB Parsing
+# ---------------------------------------------------------------------------
+
+## Parse a GLB byte array into an avatar Node3D structure.
+## Creates: Avatar (Node3D) -> Skeleton3D + BodyMeshes + AttachmentPoints
+func _parse_glb_as_avatar(glb_data: PackedByteArray, path: String) -> Node3D:
+	var avatar := Node3D.new()
+	avatar.name = "Avatar"
+
+	# Create the skeleton container.
+	var skeleton_node := Skeleton3D.new()
+	skeleton_node.name = "Skeleton3D"
+	skeleton_node.position = Vector3(0, 0, 0)
+	avatar.add_child(skeleton_node)
+
+	# Create attachment points container.
+	var attach_points := Node3D.new()
+	attach_points.name = "AttachmentPoints"
+	avatar.add_child(attach_points)
+
+	# Create body meshes container.
+	var body_meshes := Node3D.new()
+	body_meshes.name = "BodyMeshes"
+	avatar.add_child(body_meshes)
+
+	# Create attachments container.
+	var attachments_container := Node3D.new()
+	attachments_container.name = "Attachments"
+	avatar.add_child(attachments_container)
+
+	# Parse the GLB and extract skeleton + meshes.
+	# Godot's GLTFState allows custom parsing.
+	var gltf_document := GLTFDocument.new()
+	var gltf_state := GLTFState.new()
+
+	var parse_result := gltf_document.parse(glb_data, gltf_state, "", "")
+	if parse_result != OK:
+		push_error("GLB parse error: %s" % Error.parse_error(parse_result))
+		avatar.queue_free()
+		return null
+
+	# Export the scene from GLTFState.
+	var root_nodes := gltf_state.get_nodes_as_resources()
+	if root_nodes.is_empty():
+		push_error("No root nodes in GLB: %s" % path)
+		avatar.queue_free()
+		return null
+
+	# Merge GLB nodes into our avatar structure.
+	for node_resource in root_nodes:
+		if node_resource is Node3D:
+			_merge_node_into_avatar(node_resource, avatar, body_meshes,
+				attach_points, attachments_container)
+
+	return avatar
+
+
+## Parse a GLB byte array into an attachment Node3D.
+func _parse_glb_as_attachment(glb_data: PackedByteArray, path: String,
+		slot_id: String) -> Node3D:
+
+	var gltf_document := GLTFDocument.new()
+	var gltf_state := GLTFState.new()
+
+	var parse_result := gltf_document.parse(glb_data, gltf_state, "", "")
+	if parse_result != OK:
+		push_error("GLB parse error: %s" % Error.parse_error(parse_result))
+		return null
+
+	var root_nodes := gltf_state.get_nodes_as_resources()
+	if root_nodes.is_empty():
+		push_error("No root nodes in attachment GLB: %s" % path)
+		return null
+
+	var attachment := Node3D.new()
+	attachment.name = "%s_%s" % [slot_id, path.get_file().get_basename()]
+
+	for node_resource in root_nodes:
+		if node_resource is Node3D:
+			attachment.add_child(node_resource.duplicate())
+
+	return attachment
+
+
+## Merge a GLB node tree into the avatar's container structure.
+func _merge_node_into_avatar(node: Node3D, avatar: Node3D,
+		body_meshes: Node3D, attach_points: Node3D,
+		attachments_container: Node3D) -> void:
+
+	var node_name := node.name
+
+	# Identify skeleton nodes.
+	if node is Skeleton3D:
+		var src_skel := node as Skeleton3D
+		var dst_skel := avatar.get_node_or_null("Skeleton3D") as Skeleton3D
+		if dst_skel:
+			# Copy bones from source skeleton to destination.
+			for i in src_skel.get_bone_count():
+				var bone_name := src_skel.get_bone_name(i)
+				var bone_pose := src_skel.get_bone_pose(i)
+				var parent_idx := src_skel.get_bone_parent(i)
+				if dst_skel.has_bone(bone_name):
+					# Bone already exists (canonical).
+					dst_skel.set_bone_pose(i, bone_pose)
+					if parent_idx >= 0:
+						var parent_name := src_skel.get_bone_name(parent_idx)
+						var dst_parent_idx := dst_skel.find_bone(parent_name)
+						if dst_parent_idx >= 0:
+							dst_skel.set_bone_parent(i, dst_parent_idx)
+				else:
+					# Add new bone.
+					var new_idx := dst_skel.add_bone(bone_name)
+					dst_skel.set_bone_pose(new_idx, bone_pose)
+					if parent_idx >= 0:
+						var parent_name := src_skel.get_bone_name(parent_idx)
+						var dst_parent_idx := dst_skel.find_bone(parent_name)
+						if dst_parent_idx >= 0:
+							dst_skel.set_bone_parent(new_idx, dst_parent_idx)
+		return
+
+	# Identify attachment point nodes (empty nodes named attach_*).
+	if node_name.begins_with("attach_"):
+		var cloned := node.duplicate()
+		cloned.name = node_name
+		attach_points.add_child(cloned)
+		return
+
+	# Identify mesh nodes.
+	if node is MeshInstance3D:
+		var mesh_inst := node as MeshInstance3D
+		var cloned := mesh_inst.duplicate() as MeshInstance3D
+		# Determine which container to place it in.
+		if node_name == "Body" or node_name.ends_with("_Mesh"):
+			body_meshes.add_child(cloned)
+		else:
+			attachments_container.add_child(cloned)
+		return
+
+	# For other nodes, recurse into children.
+	for child in node.get_children():
+		if child is Node3D:
+			_merge_node_into_avatar(child, avatar, body_meshes,
+				attach_points, attachments_container)
+
+
+## Extract base body meshes from the avatar and store them by slot.
+func _extract_base_meshes(avatar: Node3D) -> void:
+	var body_meshes := avatar.get_node_or_null("BodyMeshes") as Node3D
+	if body_meshes == null:
+		return
+
+	for child in body_meshes.get_children():
+		if child is MeshInstance3D:
+			var mesh_name := child.name
+			var slot_id := _mesh_name_to_slot(mesh_name)
+			if slot_id != "":
+				_base_meshes[slot_id] = child
+
+
+## Map a mesh name to a slot id based on naming conventions (§4.3).
+func _mesh_name_to_slot(mesh_name: String) -> String:
+	if mesh_name == "Body":
+		# Generic body mesh - covers torso, legs, arms.
+		return "torso"
+	if mesh_name == "head_Mesh":
+		return "head"
+	if mesh_name == "torso_Mesh":
+		return "torso"
+	if mesh_name == "legs_Mesh":
+		return "legs"
+	if mesh_name == "left_arm_Mesh":
+		return "left_arm"
+	if mesh_name == "right_arm_Mesh":
+		return "right_arm"
+	return ""
+
+
+# ---------------------------------------------------------------------------
+# Internal: Skin Retargeting
+# ---------------------------------------------------------------------------
+
+## Retarget the skin weights of an attachment node to the canonical skeleton.
+## Walks all MeshInstance3D children and remaps joint indices by bone name.
+func _retarget_skin(attachment_node: Node3D) -> void:
+	if skeleton == null:
+		return
+
+	for child in attachment_node.get_children():
+		if child is MeshInstance3D:
+			var mesh_inst := child as MeshInstance3D
+			var mesh := mesh_inst.mesh
+			if mesh == null:
+				continue
+
+			# Handle MultiMeshInstance3D.
+			if mesh is MultiMesh:
+				# MultiMesh doesn't have skin weights per-vertex in the same way.
+				continue
+
+			if mesh is ArrayMesh:
+				var arr_mesh := mesh as ArrayMesh
+				var surface_count := arr_mesh.get_surface_count()
+
+				for surface_idx in surface_count:
+					var arrays := arr_mesh.surface_get_arrays(surface_idx)
+					var joints_array := arrays[Mesh.ARRAY_JOINTS] as PackedInt32Array
+					var weights_array := arrays[Mesh.ARRAY_WEIGHTS] as PackedFloat32Array
+
+					if joints_array.is_empty():
+						continue
+
+					# Remap joint indices by bone name.
+					var new_joints := PackedInt32Array()
+					for i in range(0, joints_array.size(), 4):
+						for j in 4:
+							var old_joint := joints_array[i + j]
+							if old_joint < 0:
+								new_joints.append(0)
+							else:
+								var bone_name := skeleton.get_bone_name(old_joint)
+								var new_idx := _bone_index_map.get(bone_name, 0)
+								new_joints.append(new_idx)
+
+					arrays[Mesh.ARRAY_JOINTS] = new_joints
+					arr_mesh.surface_set_arrays(surface_idx, arrays)
+
+
+## Parent an attachment node to its mount bone in the skeleton.
+func _parent_attachment(attachment_node: Node3D, slot_id: String,
+		asset_meta: Dictionary) -> void:
+
+	if skeleton == null:
+		return
+
+	var mount_bone: String = asset_meta.get("mount_bone", "")
+	if mount_bone.is_empty():
+		# Try to infer from slot.
+		mount_bone = _slot_to_mount_bone(slot_id)
+
+	if mount_bone.is_empty():
+		return
+
+	var bone_idx := skeleton.find_bone(mount_bone)
+	if bone_idx < 0:
+		return
+
+	# Get the world transform of the bone at the time of attachment.
+	var bone_pose := skeleton.get_bone_pose(bone_idx)
+	var bone_transform := skeleton.global_transform * bone_pose
+
+	# Position the attachment at the bone's location.
+	attachment_node.global_transform = bone_transform
+
+
+## Convert a slot id to its canonical mount bone name (§3.2).
+func _slot_to_mount_bone(slot_id: String) -> String:
+	match slot_id:
+		"head": return "Head"
+		"hair": return "HeadTop"
+		"face": return "Jaw"
+		"torso", "chest", "back": return "Chest"
+		"left_arm": return "LeftUpperArm"
+		"right_arm": return "RightUpperArm"
+		"left_hand": return "LeftHand"
+		"right_hand": return "RightHand"
+		"legs": return "Hips"
+		"pants": return "Hips"
+		"left_foot": return "LeftFoot"
+		"right_foot": return "RightFoot"
+		"accessory": return "Root"
+		_: return ""
+
+
+# ---------------------------------------------------------------------------
+# Internal: File Loading
+# ---------------------------------------------------------------------------
+
+## Load a file from the given path as a PackedByteArray.
+func _load_file(path: String) -> PackedByteArray:
+	var file := FileAccess.open(path, FileAccess.READ)
+	if file == null:
+		return PackedByteArray()
+	var data := file.get_buffer(file.get_length())
+	file.close()
+	return data

scripts/avatar/avatar_loadout.gd

@@ -0,0 +1,225 @@
+## AvatarLoadout - Serializable loadout model + validation.
+##
+## Represents a complete avatar composition: a base body plus equipped items
+## per slot. Validates slot exclusivity and references against a catalog.
+##
+## See docs/architecture/avatar.md §5 for the loadout JSON format.
+
+extends RefCounted
+
+
+## Maximum number of accessories allowed in the accessory slot.
+const MAX_ACCESSORIES: int = 8
+
+## The base body asset ID.
+var base_body: String = ""
+
+## Equipped items per slot. Keys are slot IDs from AvatarSlotRegistry.
+## Exclusive slots hold a single asset ID (or null).
+## The "accessory" slot holds an array of asset IDs.
+var slots: Dictionary = {}
+
+## Validation errors found during the last validate() call.
+var validation_errors: Array[String] = []
+
+
+func _init() -> void:
+	validation_errors = []
+
+
+## Create a loadout from a JSON string.
+static func from_json(json_string: String) -> AvatarLoadout:
+	var loadout := AvatarLoadout.new()
+	var data: Variant = JSON.parse_string(json_string)
+	if data is not Dictionary:
+		loadout.validation_errors.append("Loadout JSON root is not an object")
+		return loadout
+
+	var root: Dictionary = data as Dictionary
+
+	# Parse base_body
+	if root.has("base_body"):
+		var bb = root["base_body"]
+		if typeof(bb) == TYPE_STRING:
+			loadout.base_body = bb as String
+		else:
+			loadout.validation_errors.append("base_body must be a string")
+
+	# Parse slots
+	if root.has("slots"):
+		var slots_data = root["slots"]
+		if typeof(slots_data) == TYPE_DICTIONARY:
+			loadout.slots = slots_data as Dictionary
+		else:
+			loadout.validation_errors.append("slots must be an object")
+	else:
+		loadout.validation_errors.append("Missing 'slots' in loadout JSON")
+
+	return loadout
+
+
+## Serialize this loadout to a JSON string.
+func to_json() -> String:
+	var data := {
+		"base_body": base_body,
+		"slots": {}
+	}
+
+	for slot_id in AvatarSlotRegistry.SLOT_IDS:
+		if slot_id == "accessory":
+			data.slots[slot_id] = slots.get(slot_id, [])
+		else:
+			data.slots[slot_id] = slots.get(slot_id, null)
+
+	return JSON.stringify(data, "  ")
+
+
+## Validate this loadout against the slot registry.
+## Returns true if valid; populates validation_errors if not.
+func validate() -> bool:
+	validation_errors.clear()
+
+	# Check base_body
+	if base_body.is_empty():
+		validation_errors.append("base_body is required")
+
+	# Check each slot
+	for slot_id in AvatarSlotRegistry.SLOT_IDS:
+		var slot_def = AvatarSlotRegistry.get_slot(slot_id)
+		if slot_def == null:
+			validation_errors.append("Unknown slot: %s" % slot_id)
+			continue
+
+		var value = slots.get(slot_id)
+
+		if slot_def.exclusive:
+			# Exclusive slots: must be null or a string
+			if value != null and typeof(value) != TYPE_STRING:
+				validation_errors.append(
+					"Slot '%s' must be null or a string, got %s" % [
+						slot_id, typeof(value)
+					]
+				)
+		else:
+			# Non-exclusive (accessory): must be null or an array
+			if value != null and typeof(value) != TYPE_ARRAY:
+				validation_errors.append(
+					"Slot '%s' must be null or an array, got %s" % [
+						slot_id, typeof(value)
+					]
+				)
+			elif value is Array:
+				if slot_id == "accessory":
+					if value.size() > MAX_ACCESSORIES:
+						validation_errors.append(
+							"Accessory count (%d) exceeds maximum (%d)" % [
+								value.size(), MAX_ACCESSORIES
+							]
+						)
+
+	# Check for duplicate accessories
+	if slots.has("accessory") and slots["accessory"] is Array:
+		var accessories = slots["accessory"] as Array
+		var seen := {}
+		for item in accessories:
+			if item is String:
+				if seen.has(item):
+					validation_errors.append(
+						"Duplicate accessory: %s" % item
+					)
+				seen[item] = true
+
+	return validation_errors.is_empty()
+
+
+## Check if a specific slot is equipped with a non-null item.
+func is_equipped(slot_id: String) -> bool:
+	if not AvatarSlotRegistry.has_slot(slot_id):
+		return false
+
+	var value = slots.get(slot_id)
+	if value == null:
+		return false
+
+	if typeof(value) == TYPE_STRING:
+		return not (value as String).is_empty()
+	elif typeof(value) == TYPE_ARRAY:
+		return (value as Array).size() > 0
+
+	return false
+
+
+## Get the equipped asset ID for an exclusive slot.
+## Returns empty string if not equipped or slot is not exclusive.
+func get_equipment(slot_id: String) -> String:
+	var value = slots.get(slot_id)
+	if value is String:
+		return value
+	return ""
+
+
+## Set equipment for an exclusive slot.
+func set_equipment(slot_id: String, asset_id: String) -> void:
+	if not AvatarSlotRegistry.has_slot(slot_id):
+		push_error("Unknown slot: %s" % slot_id)
+		return
+
+	var slot_def = AvatarSlotRegistry.get_slot(slot_id)
+	if slot_def and not slot_def.exclusive:
+		push_error("Slot '%s' is not exclusive" % slot_id)
+		return
+
+	if slots.has(slot_id):
+		var current = slots[slot_id]
+		if current is Array:
+			# Convert array to single value
+			slots[slot_id] = asset_id if asset_id.is_empty() else null
+		else:
+			slots[slot_id] = asset_id if not asset_id.is_empty() else null
+	else:
+		slots[slot_id] = asset_id if not asset_id.is_empty() else null
+
+
+## Add an accessory to the accessory slot.
+func add_accessory(asset_id: String) -> bool:
+	var accessories = slots.get("accessory", []) as Array
+	if accessories.size() >= MAX_ACCESSORIES:
+		return false
+	if asset_id.is_empty():
+		return false
+	if accessories.has(asset_id):
+		return false
+	accessories.append(asset_id)
+	slots["accessory"] = accessories
+	return true
+
+
+## Remove an accessory from the accessory slot.
+func remove_accessory(asset_id: String) -> bool:
+	var accessories = slots.get("accessory", []) as Array
+	if accessories.has(asset_id):
+		accessories.erase(asset_id)
+		slots["accessory"] = accessories
+		return true
+	return false
+
+
+## Compute a hash of this loadout for change detection.
+## Mirrors the server's loadout_hash concept.
+func compute_hash() -> int:
+	var hasher := HashingContext.new()
+	hasher.start(HashingContext.HASH_SHA256)
+	hasher.update(base_body.to_utf8_buffer())
+	for slot_id in AvatarSlotRegistry.SLOT_IDS:
+		hasher.update(slot_id.to_utf8_buffer())
+		var value = slots.get(slot_id)
+		if value is String:
+			hasher.update(value.to_utf8_buffer())
+		elif value is Array:
+			var arr_str = JSON.stringify(value)
+			hasher.update(arr_str.to_utf8_buffer())
+		else:
+			hasher.update("null".to_utf8_buffer())
+	var digest = hasher.finish()
+	# Return first 4 bytes as int for compact storage
+	return digest[0] | (digest[1] << 8) | (digest[2] << 16) | (digest[3] << 24)

scripts/avatar/avatar_visualizer.gd

@@ -0,0 +1,285 @@
+## AvatarVisualizer
+##
+## Builds the render tree from an AvatarLoadout.
+##
+## Responsibilities:
+##   - Create a root Node3D (or Node2D for 2D mode) as the avatar container.
+##   - For each slot in the loadout, call AvatarLoader.load_slot() and attach
+##     the resulting Skeleton3D / MeshInstance3D tree to the root.
+##   - Apply skin-tone overrides to all MeshInstance3D nodes.
+##   - Apply a single Skeleton3D root (the "body" skeleton) and retarget all
+##     limb skeletons to it using the bone-map from AvatarSlotRegistry.
+##   - Expose `get_root()` for the caller to attach to the scene tree.
+##   - Expose `clear()` to destroy the tree and free resources.
+##
+## Usage:
+##   var viz = AvatarVisualizer.new()
+##   viz.load_loadout(loadout)
+##   avatar_node.add_child(viz.get_root())
+##
+## The visualizer owns the Skeleton3D and MeshInstance3D trees it creates.
+## The caller owns the root node's placement in the scene tree.
+
+class_name AvatarVisualizer
+extends Object
+
+
+## Emitted when the visualizer has finished building the render tree.
+signal build_complete
+## Emitted when the visualizer has been cleared.
+signal cleared
+
+
+# ---------------------------------------------------------------------------
+# Public API
+# ---------------------------------------------------------------------------
+
+## The root node that holds the avatar render tree.
+## Set this to the desired parent before calling load_loadout().
+var root: Node3D = null
+
+## The Skeleton3D that serves as the body skeleton.
+## All limb skeletons are retargeted to this skeleton's bone hierarchy.
+var body_skeleton: Skeleton3D = null
+
+## The AvatarLoadout currently loaded (null if none).
+var current_loadout: AvatarLoadout = null
+
+## Whether the visualizer is currently building (true during load_loadout).
+var is_building: bool = false
+
+
+# ---------------------------------------------------------------------------
+# Core
+# ---------------------------------------------------------------------------
+
+## Load an AvatarLoadout and build the render tree.
+##
+## If [param root] is null, a new Node3D is created and assigned.
+## If [param loadout] is null or invalid, the current tree is cleared.
+func load_loadout(loadout: AvatarLoadout, root_node: Node3D = null) -> void:
+	# Clear any previous tree.
+	clear()
+
+	if loadout == null or not loadout.is_valid():
+		build_complete.emit()
+		return
+
+	current_loadout = loadout
+	is_building = true
+
+	# Create root if not provided.
+	if root_node != null:
+		root = root_node
+	else:
+		root = Node3D.new()
+		root.name = "AvatarVisualizer"
+
+	# Create the body skeleton.
+	body_skeleton = Skeleton3D.new()
+	body_skeleton.name = "AvatarBody"
+	root.add_child(body_skeleton)
+
+	# Build each slot's contribution.
+	for slot_def in AvatarSlotRegistry.get_slot_definitions():
+		var slot_key: String = slot_def.slot_key
+		var slot_item: AvatarLoadout.SlotItem = loadout.slots.get(slot_key)
+
+		if slot_item == null or slot_item.asset_id == "":
+			# Slot is empty — create a placeholder.
+			_add_placeholder_slot(slot_def)
+			continue
+
+		# Load the slot's asset.
+		var slot_result: AvatarLoader.SlotResult = await AvatarLoader.load_slot(
+			slot_item,
+			slot_def,
+			loadout.skin_tone,
+		)
+
+		if slot_result == null:
+			push_warning("AvatarVisualizer: failed to load slot '%s' (%s)" % [slot_key, slot_item.asset_id])
+			_add_placeholder_slot(slot_def)
+			continue
+
+		# Attach the loaded tree to the root.
+		_attach_slot_tree(slot_result, slot_def)
+
+	# Retarget limb skeletons to the body skeleton.
+	_retarget_limbs()
+
+	# Apply skin-tone override to all meshes.
+	_apply_skin_tone(loadout.skin_tone)
+
+	is_building = false
+	build_complete.emit()
+
+
+## Clear the render tree and free resources.
+func clear() -> void:
+	if root != null:
+		root.queue_free()
+		root = null
+		body_skeleton = null
+		current_loadout = null
+		cleared.emit()
+
+
+## Get the root node.
+func get_root() -> Node3D:
+	return root
+
+
+## Get a specific slot's Skeleton3D (if it has one).
+func get_slot_skeleton(slot_key: String) -> Skeleton3D:
+	if body_skeleton == null:
+		return null
+	var bones := body_skeleton.get_bone_count()
+	for i in range(bones):
+		var bone_name: String = body_skeleton.get_bone_name(i)
+		if bone_name == slot_key:
+			return body_skeleton
+	return null
+
+
+## Get all MeshInstance3D nodes in the render tree.
+func get_all_mesh_instances() -> Array[MeshInstance3D]:
+	var meshes: Array[MeshInstance3D] = []
+	if root == null:
+		return meshes
+	_collect_meshes(root, meshes)
+	return meshes
+
+
+## Get all Skeleton3D nodes in the render tree.
+func get_all_skeletons() -> Array[Skeleton3D]:
+	var skeletons: Array[Skeleton3D] = []
+	if root == null:
+		return skeletons
+	_collect_skeletons(root, skeletons)
+	return skeletons
+
+
+# ---------------------------------------------------------------------------
+# Internal helpers
+# ---------------------------------------------------------------------------
+
+## Add a placeholder (empty) skeleton for a slot that has no asset.
+func _add_placeholder_slot(slot_def: AvatarSlotRegistry.SlotDefinition) -> void:
+	if body_skeleton == null:
+		return
+
+	var bone_name: String = slot_def.slot_key
+	var bone_id: int = body_skeleton.add_bone(bone_name)
+
+	# Set the bone's rest pose to identity (placeholder).
+	var rest := Transform3D()
+	rest.origin = slot_def.default_offset
+	body_skeleton.set_bone_rest(bone_id, rest)
+
+	# Set parent to root (bone 0 is the root bone).
+	body_skeleton.set_bone_parent(bone_id, 0)
+
+
+## Attach a loaded slot's tree to the root.
+func _attach_slot_tree(result: AvatarLoader.SlotResult, slot_def: AvatarSlotRegistry.SlotDefinition) -> void:
+	if result.skeleton == null:
+		return
+
+	# Add the skeleton as a child of the body skeleton.
+	# The skeleton's bones will be merged into the body skeleton during retargeting.
+	result.skeleton.name = "%s_skeleton" % slot_def.slot_key
+	result.skeleton.visible = true
+	root.add_child(result.skeleton)
+
+
+## Retarget all limb skeletons to the body skeleton.
+func _retarget_limbs() -> void:
+	if body_skeleton == null:
+		return
+
+	# Collect all child Skeleton3D nodes (limb skeletons).
+	var limb_skeletons: Array[Skeleton3D] = []
+	for child in root.get_children():
+		if child is Skeleton3D and child != body_skeleton:
+			limb_skeletons.append(child as Skeleton3D)
+
+	# For each limb skeleton, merge its bones into the body skeleton.
+	for limb in limb_skeletons:
+		_merge_skeleton_into_body(limb)
+		limb.queue_free()
+
+
+## Merge a limb skeleton's bones into the body skeleton.
+func _merge_skeleton_into_body(limb: Skeleton3D) -> void:
+	if limb == null or body_skeleton == null:
+		return
+
+	var limb_bone_count: int = limb.get_bone_count()
+	var start_id: int = body_skeleton.get_bone_count()
+
+	for i in range(limb_bone_count):
+		var bone_name: String = limb.get_bone_name(i)
+		var bone_id: int = body_skeleton.add_bone(bone_name)
+
+		# Copy the rest transform.
+		var rest: Transform3D = limb.get_bone_rest(i)
+		body_skeleton.set_bone_rest(bone_id, rest)
+
+		# Copy the parent.
+		var parent_id: int = limb.get_bone_parent(i)
+		if parent_id >= 0:
+			# Map parent ID to body skeleton.
+			if parent_id == 0:
+				# Root of limb skeleton -> parent is the body root.
+				body_skeleton.set_bone_parent(bone_id, 0)
+			else:
+				# Offset by start_id to map to body skeleton bones.
+				body_skeleton.set_bone_parent(bone_id, start_id + parent_id)
+		else:
+			body_skeleton.set_bone_parent(bone_id, 0)
+
+		# Copy custom bone data (if any).
+		var custom_data_count: int = limb.get_bone_custom_data_count(i)
+		for j in range(custom_data_count):
+			var data: Variant = limb.get_bone_custom_data(i, j)
+			body_skeleton.set_bone_custom_data(bone_id, j, data)
+
+		# Copy mesh connections.
+		var mesh_count: int = limb.get_bone_mesh_count(i)
+		for m in range(mesh_count):
+			var mesh: MeshInstance3D = limb.get_bone_mesh(i, m)
+			if mesh != null:
+				# Re-parent mesh to body skeleton.
+				mesh.skeleton = body_skeleton
+				mesh.skeleton_path = body_skeleton.get_path()
+				body_skeleton.add_bone_mesh(bone_id, mesh)
+
+
+## Apply skin-tone override to all MeshInstance3D nodes.
+func _apply_skin_tone(skin_tone: Color) -> void:
+	if skin_tone == Color.TRANSPARENT:
+		return
+
+	var meshes: Array[MeshInstance3D] = get_all_mesh_instances()
+	for mesh_instance in meshes:
+		if mesh_instance.material_override == null:
+			mesh_instance.material_override = StandardMaterial3D.new()
+		var mat: StandardMaterial3D = mesh_instance.material_override
+		mat.albedo_color = skin_tone
+
+
+## Recursively collect all MeshInstance3D nodes.
+func _collect_meshes(node: Node, result: Array[MeshInstance3D]) -> void:
+	if node is MeshInstance3D:
+		result.append(node as MeshInstance3D)
+	for child in node.get_children():
+		_collect_meshes(child, result)
+
+
+## Recursively collect all Skeleton3D nodes.
+func _collect_skeletons(node: Node, result: Array[Skeleton3D]) -> void:
+	if node is Skeleton3D:
+		result.append(node as Skeleton3D)
+	for child in node.get_children():
+		_collect_skeletons(child, result)