M2.2: player bodies, name tags, shared island and checked movement

- Joining loads the server's island (seed, spawn, clock); the server
  generates the same terrain from its seed and keeps a world clock that
  pauses when empty
- Other players are procedural low-poly characters in their chosen colours
  with name tags (hidden by walls, fading with distance), walk/run/swim
  animation and held items
- Movement: local and instant, sent at 20 Hz stamped with the sender's
  clock; the server refuses impossible moves (speed, rising, leaving the
  island, underground) and sends the player back; flagged respawns allowed
- Avatars drawn 100 ms behind and interpolated, with brief extrapolation
- Online: no pausing, player list in the Esc menu, Disconnect back to the
  title (with the reason); animals off and world changes local-only until
  M2.3-M2.5, shown on the HUD
- test_net_world: real server + walking and cheating bots at 100 ms +/-
  30 ms simulated latency (27 checks)

scripts/world/terrain.gd

@@ -69,9 +69,13 @@ var _heights := PackedFloat32Array()
 var _normals := PackedVector3Array()
 
 func _ready() -> void:
-	# A saved world brings its own seed; otherwise keep the exported default.
+	# On a server, its seed; in a saved world, that world's seed; otherwise
+	# keep the exported default.
+	var net := get_node_or_null("/root/Net")
 	var saves := get_node_or_null("/root/Saves")
-	if saves != null and saves.has_world():
+	if net != null and net.state == "connected" and net.world_info.has("seed"):
+		noise_seed = int(net.world_info.seed)
+	elif saves != null and saves.has_world():
 		noise_seed = saves.world_seed()
 	_build()
 

scripts/world/world.gd

@@ -26,6 +26,7 @@ const PIECES := {
 	"bed": preload("res://scripts/building/bed.gd"),
 }
 const BuildPiece = preload("res://scripts/building/build_piece.gd")
+const UITheme = preload("res://scripts/ui/theme.gd")
 
 const AUTOSAVE_SECONDS := 120.0
 
@@ -50,8 +51,13 @@ var _dropped: Node3D            ## arrows, spears and other dropped items
 var den: Node3D                 ## den.gd: the wolves' cave at the foot of the rim
 var bobber: Node3D              ## bobber.gd: the cast fishing float, if any
 var wolves: Node3D              ## wolf_pack.gd (null if this seed has no den site)
+var net_sync: Node              ## net_sync.gd when playing on a server, else null
 var has_bed_spawn := false
 var bed_spawn := Vector3.ZERO   ## position of the bed you respawn at
+
+## Playing on a server (multiplayer) rather than a local world.
+func is_online() -> bool:
+	return not menu_mode and Net.state == "connected"
 var _loading := false           ## applying a save: defer support recompute
 
 func _ready() -> void:
@@ -157,7 +163,7 @@ func _on_player_died() -> void:
 		player.inventory.load_data(Inventory.new(player.inventory.size()).to_data())
 	if hud != null:
 		hud.close_screens()
-	var bed := spawn_bed()
+	var bed := spawn_bed() if net_sync == null else null   # (online: beds aren't shared until M2.4)
 	if bed != null:
 		_respawn_at_bed(bed)
 	else:
@@ -258,6 +264,10 @@ func _on_terrain_ready() -> void:
 	player.set_physics_process(true)
 	set_physics_process(true)
 	creatures.setup(self)
+	if is_online():
+		_go_online()
+		_maybe_capture()
+		return
 	if not "--no-creatures" in OS.get_cmdline_user_args():
 		creatures.populate()
 		creatures.enabled = true
@@ -301,7 +311,13 @@ func save_now() -> bool:
 	return ok
 
 func _notification(what: int) -> void:
-	if what == NOTIFICATION_WM_CLOSE_REQUEST and Saves.has_world() and not menu_mode:
+	if what != NOTIFICATION_WM_CLOSE_REQUEST or menu_mode:
+		return
+	if net_sync != null:
+		Net.left.disconnect(_on_net_left)
+		Net.leave()
+		get_tree().quit()
+	elif Saves.has_world():
 		save_now()
 		get_tree().quit()
 
@@ -421,6 +437,8 @@ func apply_save(s: Dictionary) -> void:
 	_update_grass_cuts()
 
 func _respawn() -> void:
+	if net_sync != null:
+		net_sync.mark_teleport()   # tell the server this jump back to the spawn is legitimate
 	player.global_position = _spawn + Vector3(0.0, 1.5, 0.0)
 	player.velocity = Vector3.ZERO
 	player.rotation = Vector3(0.0, _spawn_yaw, 0.0)
@@ -498,6 +516,34 @@ func water_at(x: float, z: float) -> Dictionary:
 		return {"type": "sea", "surface": terrain.sea_level, "depth": terrain.sea_level - ground}
 	return {}
 
+# --- multiplayer -----------------------------------------------------------------
+
+## Joined a server: start where it says, follow its clock, show the others.
+## Animals stay off until the server runs them (M2.5): otherwise everyone
+## would see different wildlife.
+func _go_online() -> void:
+	_spawn = Net.world_info.get("island_spawn", _spawn)
+	var start: Vector3 = Net.world_info.get("spawn", _spawn)
+	player.global_position = start + Vector3(0.0, 0.05, 0.0)
+	net_sync = preload("res://scripts/net/net_sync.gd").new()
+	net_sync.name = "NetSync"
+	add_child(net_sync)
+	net_sync.setup(self)
+	Net.left.connect(_on_net_left)
+	get_tree().auto_accept_quit = false   # leave the server cleanly on window close
+	if hud != null:
+		var bar := UITheme.label("Online: %s  ·  you can see each other; building, gathering and animals aren't shared yet" \
+			% Net.server_info.get("server_name", "server"), 14, UITheme.TEXT_DIM)
+		bar.position = Vector2(16, 40)
+		$HUD.add_child(bar)
+	Actions.notify.emit("Connected to %s" % Net.server_info.get("server_name", "the server"))
+
+func _on_net_left(_reason: String) -> void:
+	if is_inside_tree():
+		get_tree().paused = false
+		get_tree().auto_accept_quit = true
+		get_tree().change_scene_to_file.call_deferred("res://scenes/title.tscn")
+
 ## Leaves `count` of an item lying in the world at `xf` (an arrow stuck in a
 ## tree, a thrown spear, meat that didn't fit). Saved with the world.
 func drop_item(id: String, count: int, xf: Transform3D) -> Node3D:
@@ -692,6 +738,50 @@ func _capture_survival(prefix: String, cam: Camera3D) -> void:
 	await _capture_weather(prefix, cam)
 	await _capture_creatures(prefix, cam)
 	await _capture_wolves_fishing(prefix, cam)
+	await _capture_players(prefix, cam)
+
+## Two sample players (as other people would see them) at the camp.
+func _capture_players(prefix: String, cam: Camera3D) -> void:
+	weather.force("clear")
+	weather.snow_cover = 0.0
+	weather.ground_wet = 0.0
+	day_night.time = 10.0 / 24.0
+	day_night.apply(true)
+	_respawn()
+	player.set_physics_process(false)
+	var fwd := -player.global_basis.z
+	var right := player.global_basis.x
+	var root := Node3D.new()
+	add_child(root)
+	var AvatarScript = preload("res://scripts/net/avatar.gd")
+	var made: Array = []
+	for d in [["Freya", {"tunic": 2, "hair": 2, "beard": false}, 3.2, -0.9, "stone_axe", 1],
+			["Old Bjorn", {"tunic": 1, "hair": 4, "beard": true}, 4.4, 1.3, "", 0]]:
+		var av: Node3D = AvatarScript.new()
+		av.setup(made.size() + 2, {"name": d[0], "appearance": d[1]})
+		root.add_child(av)
+		var p: Vector3 = player.global_position + fwd * float(d[2]) + right * float(d[3])
+		p.y = terrain.sample_height(p.x, p.z)
+		var face: float = player.rotation.y + PI + float(d[3]) * 0.3
+		av.push(0.0, p, face, 0.0, d[5], d[4])
+		av.push(1.0, p + fwd * 0.01 * d[5], face, 0.0, d[5], d[4])
+		made.append(av)
+	player.select(0)
+	cam.rotation.x = -0.12
+	for i in range(30):
+		for av in made:
+			av.update_at(0.5 + i * 0.016, 0.016)
+		await get_tree().process_frame
+	await RenderingServer.frame_post_draw
+	get_viewport().get_texture().get_image().save_png("%s_players.png" % prefix)
+	print("[world] saved %s_players.png" % prefix)
+	day_night.time = 19.2 / 24.0
+	day_night.apply(true)
+	await get_tree().create_timer(0.5).timeout
+	await RenderingServer.frame_post_draw
+	get_viewport().get_texture().get_image().save_png("%s_players_dusk.png" % prefix)
+	print("[world] saved %s_players_dusk.png" % prefix)
+	root.queue_free()
 
 ## The den by day with the pack resting, wolves stalking at night, and
 ## fishing from the lake shore.