The Cove's shore life: crabs up the beach from dusk till dawn (keep to the sand, pinch if you get close, crab meat to cook), gulls after food on the sand and fish on a smoking rack; online too

scripts/creatures/shore.gd

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+extends Node3D
+## The shore's own wildlife (0.6.0, a land whose worldlet lists "crabs" in
+## its "wildlife": the Cove). From dusk till dawn crabs come up out of the
+## sea onto the beach, a few around each player who's down on the sand, at
+## the waterline and out of the way. At dawn they go back in (crab.gd).
+## Not saved: like the other wildlife they simply carry on around you.
+##
+## On a server this runs for everyone, and players see the crabs through
+## creature_net.gd.
+
+const CrabScript = preload("res://scripts/creatures/crab.gd")
+
+const BUDGET := 5                ## per player on the beach, up to twice it
+const CHECK_EVERY := 2.0
+const RING_MIN := 14.0
+const RING_MAX := 45.0
+const NOT_WITHIN := 10.0         ## never comes up right beside anyone
+const DESPAWN := 80.0
+const BEACH_NEAR := 40.0         ## a player this close to the sand counts as on the beach
+
+var world: Node3D
+var terrain: Node3D
+var enabled := true
+var _rng := RandomNumberGenerator.new()
+var _acc := 0.0
+var _serial := 0
+
+func setup(w: Node3D) -> void:
+	world = w
+	terrain = w.terrain
+	_rng.seed = terrain.noise_seed + 1201
+
+func _physics_process(delta: float) -> void:
+	step(delta)
+
+## Dusk till dawn.
+func night() -> bool:
+	var h: float = world.day_night.hours()
+	return h >= 17.5 or h < 6.5
+
+## Living crabs.
+func alive() -> Array:
+	return get_children().filter(func(c): return is_instance_valid(c) and not c.is_queued_for_deletion() and not c.is_dead())
+
+func step(dt: float) -> void:
+	if not enabled or world.creatures == null or not world.creatures.enabled:
+		return
+	_acc += dt
+	if _acc < CHECK_EVERY:
+		return
+	_acc = 0.0
+	var everyone: Array = world.players()
+	for c in get_children():
+		if not everyone.any(func(p): return p.global_position.distance_to(c.global_position) <= DESPAWN):
+			c.queue_free()
+	if not night() or everyone.is_empty():
+		return
+	var on_beach := everyone.filter(func(p): return _near_sand(p.global_position))
+	if on_beach.is_empty():
+		return
+	if alive().size() < BUDGET * clampi(on_beach.size(), 1, 2):
+		var who: Node3D = on_beach[_rng.randi() % on_beach.size()]
+		spawn_near(who.global_position)   # (one at a time: they trickle up out of the sea)
+
+func _near_sand(p: Vector3) -> bool:
+	for a in [0.0, 1.0, 2.0, 3.0, 4.0, 5.0]:
+		var q := p + Vector3(cos(a), 0.0, sin(a)) * BEACH_NEAR * 0.5
+		if terrain.on_sand(p.x, p.z) or terrain.on_sand(q.x, q.z):
+			return true
+	return false
+
+## A spot on the sand at the waterline, RING_MIN..RING_MAX from `around`
+## and not right beside anyone, or Vector3.INF.
+func find_spot(around: Vector3) -> Vector3:
+	for _try in range(40):
+		var a := _rng.randf() * TAU
+		var r := _rng.randf_range(RING_MIN, RING_MAX)
+		var x := around.x + cos(a) * r
+		var z := around.z + sin(a) * r
+		if not terrain.inside_boundary(x, z, 6.0) or terrain.beach_weight(x, z) < 0.75:
+			continue
+		var h: float = terrain.sample_height(x, z)
+		if h < terrain.water_level + 0.25 or h > terrain.water_level + 0.9:
+			continue
+		var p := Vector3(x, h, z)
+		if world.players().any(func(pl): return pl.global_position.distance_to(p) < NOT_WITHIN):
+			continue
+		return p
+	return Vector3.INF
+
+func spawn_near(around: Vector3) -> Node3D:
+	var p := find_spot(around)
+	if p == Vector3.INF:
+		return null
+	return spawn(p)
+
+func spawn(pos: Vector3) -> Node3D:
+	var c: AnimatableBody3D = CrabScript.new()
+	_serial += 1
+	c.setup("crab", world, pos, _rng.randi() + _serial)
+	add_child(c)
+	c.global_position = Vector3(pos.x, terrain.sample_height(pos.x, pos.z), pos.z)
+	c.state = "wander"
+	c.yaw = _rng.randf() * TAU
+	c.target_yaw = c.yaw
+	return c