spaceship/enemies/EnemySpawner.gd

extends Node2D

# The wave director (#100 / #97). Keeps its old node name on purpose: it is
# still "the thing that puts enemies in the world", and every test that
# wanted a quiet world already says
# `main.get_node("EnemySpawner").set_process(false)`. Renaming it would have
# changed 88 test files to say the same thing differently.
#
# What it no longer does is trickle. It used to spawn one enemy every 3-6
# seconds for ever, so there was no rhythm to the danger and nothing to
# prepare for. Now the CLOCK lives in GameState (which survives the trip to
# a planet surface) and this node only reacts to it: when a wave turns
# active, it puts the wave in the world; when the wave is dead, it says so
# and the quiet starts again.

@export var spawn_margin: float = 150.0
# Waves arrive as a ring around the fleet rather than from one bearing: a
# wave that all came from the left would be dodged by flying right.
@export var wave_spread: float = 0.55

@onready var fleet: Node2D = get_node("../Fleet")

var enemy_scene: PackedScene = preload("res://enemies/Enemy.tscn")
# The enemies this director launched, so "the wave is dead" is a question
# about THIS wave and not about every enemy on the map - a planet garrison
# or an enemy mothership's own spawns must not hold the next wave back.
var wave_enemies: Array = []


func _process(_delta: float) -> void:
	wave_enemies = wave_enemies.filter(func(e): return is_instance_valid(e))
	if GameState.wave_pending:
		_launch_wave()
		return
	if GameState.wave_phase == GameState.WAVE_PHASE_ACTIVE and wave_enemies.is_empty():
		GameState.wave_cleared()


# Public so a test can put a wave in the world without waiting out the peace.
func _launch_wave() -> void:
	if fleet == null or fleet.ships.is_empty():
		# Nothing to attack. Leave it pending rather than spending the wave
		# on an empty map - the fleet-wipe safety net rebuilds within a frame
		# and the wave arrives then.
		return
	GameState.wave_pending = false
	var composition: PackedStringArray = GameState.wave_composition(fleet.ships.size())
	var visible_rect: Rect2 = ViewUtils.get_visible_world_rect(self)
	var radius: float = visible_rect.size.length() / 2.0 + spawn_margin
	var centre: Vector2 = fleet.get_centroid()
	var bearing: float = randf() * TAU
	for i in range(composition.size()):
		# Spread around one bearing rather than scattered at random: a wave
		# should read as an attack arriving, not as the map filling up.
		var angle: float = bearing + randf_range(-wave_spread, wave_spread) \
			+ TAU * float(i) / float(maxi(composition.size(), 1)) * wave_spread
		var enemy: Node2D = enemy_scene.instantiate()
		# Before add_child: Enemy._ready() resolves enemy_id into a definition.
		enemy.enemy_id = composition[i]
		# #113: a wave is an attack on what the player has built. It converges
		# on the nearest structure from wherever it spawned rather than
		# waiting to be flown near.
		enemy.relentless = true
		enemy.position = centre + Vector2(cos(angle), sin(angle)) * radius
		get_parent().add_child(enemy)
		wave_enemies.append(enemy)