W1: choose a worldlet (New World and Host Game pages, kept once an island exists), worldlet shown in the Load list; Godot .uid files

scripts/ui/title_screen.gd

@@ -370,6 +370,7 @@ func _host_page() -> Control:
 		_host_preset.add_item(n)
 	_host_preset.custom_minimum_size = Vector2(420, 36)
 	v.add_child(_host_preset)
+	_host_worldlet = _worldlet_picker(v)
 	var row := HBoxContainer.new()
 	row.add_theme_constant_override("separation", 10)
 	var c1 := VBoxContainer.new()
@@ -424,6 +425,7 @@ func _fill_host() -> void:
 	_host_seed.editable = not existing
 	_host_seed_label.text = "Seed" if not existing else "Seed (kept)"
 	_host_seed.text = "" if not existing else str(int(c.data.seed))
+	_show_host_worldlet(existing, meta_path)
 	_host_msg.text = "Your hosted island carries on where you left it." if existing else "A new island will be made."
 	_host_msg.add_theme_color_override("font_color", UITheme.TEXT_DIM)
 	_host_btn.disabled = false
@@ -439,7 +441,8 @@ func _start_host() -> void:
 	if name.is_empty():
 		name = "%s's island" % Net.get_identity().name
 	_host_btn.disabled = true
-	Net.host(name, _host_pw.text, int(port_t), PRESET_IDS[maxi(_host_preset.selected, 0)], seed)
+	Net.host(name, _host_pw.text, int(port_t), PRESET_IDS[maxi(_host_preset.selected, 0)], seed,
+		picked_worldlet(_host_worldlet))
 
 func _on_host_status(text: String, failed: bool) -> void:
 	if not _pages["host"].visible:
@@ -591,6 +594,7 @@ func _new_page() -> Control:
 		_rot_pick.add_item(t[1])
 	_rot_pick.custom_minimum_size = Vector2(360, 36)
 	v.add_child(_rot_pick)
+	_worldlet_pick = _worldlet_picker(v)
 	var h := HBoxContainer.new()
 	h.add_theme_constant_override("separation", 10)
 	h.add_child(_button("Create & Play", _create, 170))
@@ -633,7 +637,8 @@ func _fill_list() -> void:
 		info.add_child(UITheme.label(w.name, 18))
 		var played := int(w.get("play_time", 0.0))
 		var when := Time.get_datetime_string_from_unix_time(int(w.get("last_played", 0)), true)
-		info.add_child(UITheme.label("seed %d  ·  played %dh %02dm  ·  %s" % [int(w.seed), played / 3600, (played / 60) % 60, when], 13, UITheme.TEXT_DIM))
+		info.add_child(UITheme.label("%s  ·  seed %d  ·  played %dh %02dm  ·  %s" % [Terrain.worldlet_name(String(w.get("worldlet", "valley"))),
+			int(w.seed), played / 3600, (played / 60) % 60, when], 13, UITheme.TEXT_DIM))
 		h.add_child(info)
 		h.add_child(_button("Play", _play.bind(w.id), 80))
 		var del := Button.new()
@@ -681,7 +686,68 @@ func _create() -> void:
 	var seed_text := _seed_edit.text.strip_edges()
 	var seed := int(seed_text) if seed_text.is_valid_int() else (seed_text.hash() if not seed_text.is_empty() else randi())
 	var rot: String = ROT_CHOICES[maxi(_rot_pick.selected, 0)][0]
-	_play(Saves.create_world(world_name, seed, {"rot": rot}))
+	_play(Saves.create_world(world_name, seed, {"rot": rot, "worldlet": picked_worldlet(_worldlet_pick)}))
+
+# --- worldlets (docs/WORLDLETS_DESIGN.md, W1) -----------------------------------------
+
+const Terrain = preload("res://scripts/world/terrain.gd")
+var _worldlet_pick: OptionButton
+var _host_worldlet: OptionButton
+
+## "Where": the worldlets a new world can start in, with the chosen one's
+## description under it. (Only the Valley today: the others are reached on
+## the journey, so the list is short and the picker sits still.)
+func _worldlet_picker(v: VBoxContainer) -> OptionButton:
+	var starts: Array = Terrain.starting_worldlets()
+	v.add_child(UITheme.label("Where", 15, UITheme.TEXT_DIM))
+	var pick := OptionButton.new()
+	pick.custom_minimum_size = Vector2(360, 36)
+	pick.focus_mode = Control.FOCUS_NONE
+	for w in starts:
+		pick.add_item(String(w.name))
+		pick.set_item_metadata(pick.item_count - 1, String(w.id))
+	pick.disabled = starts.size() < 2
+	v.add_child(pick)
+	var about := UITheme.label(String(starts[0].description) if not starts.is_empty() else "", 13, UITheme.TEXT_DIM)
+	about.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	about.custom_minimum_size = Vector2(360, 0)
+	v.add_child(about)
+	pick.item_selected.connect(func(i: int):
+		about.text = String(Terrain.load_worldlet(String(pick.get_item_metadata(i))).get("description", "")))
+	return pick
+
+## The Host page's "Where": a hosted island keeps its worldlet, like its
+## seed, so once it exists the picker shows that one and stays put.
+func _show_host_worldlet(existing: bool, meta_path: String) -> void:
+	var id := "valley"
+	if existing:
+		var meta: Variant = JSON.parse_string(FileAccess.get_file_as_string(meta_path))
+		if meta is Dictionary:
+			id = String(meta.get("worldlet", "valley"))
+	var i := select_worldlet(_host_worldlet, id)
+	if i >= 0:
+		_host_worldlet.item_selected.emit(i)
+	_host_worldlet.disabled = existing or _host_worldlet.item_count < 2
+
+## Selects worldlet `id` in `pick`, adding it if it isn't a starting one
+## (an island made somewhere else). Returns its index, or -1.
+static func select_worldlet(pick: OptionButton, id: String) -> int:
+	for i in pick.item_count:
+		if String(pick.get_item_metadata(i)) == id:
+			pick.select(i)
+			return i
+	if Terrain.load_worldlet(id).is_empty():
+		return -1
+	pick.add_item(Terrain.worldlet_name(id))
+	pick.set_item_metadata(pick.item_count - 1, id)
+	pick.select(pick.item_count - 1)
+	return pick.item_count - 1
+
+## The id of the worldlet chosen in `pick` (the Valley if nothing is).
+static func picked_worldlet(pick: OptionButton) -> String:
+	if pick == null or pick.item_count == 0 or pick.selected < 0:
+		return "valley"
+	return String(pick.get_item_metadata(pick.selected))
 
 ## The tutorial (docs/TUTORIAL_DESIGN.md): its own world on the original
 ## island (seed 1337), made the first time and carried on after that.