The_Dark_Side_of_Earth/enemies/leech.gd

extends Node2D
@export var broadth = 250
@export var move_dir = -1
@export var angular_speed = 0.25
@export var hp = 400
var angle = 0.0 if move_dir == 1 else PI

@onready var segments : Array[Node] = $Segments.get_children()
@onready var segment_count = segments.size()
var paused = false
var pause_time = 0.1
var iframes = 0.2
var iframe_time = 0

var check_grounded_delay = 8

func _ready() -> void:
	for segment in segments:
		segment.segment_damaged.connect(hurt)

func _physics_process(delta: float) -> void:
	iframe_time = max(0, iframe_time - delta)
	if not paused:
		angle -= TAU * delta * angular_speed * move_dir
		if(angle > PI or angle < 0):
			paused = true
			await get_tree().create_timer(pause_time).timeout
			paused = false
			angle = fmod(angle + PI, PI)
			var y = position.length()
			var ratio = - move_dir * broadth / (2 * y)
			var rot_angle = - 2 * asin(ratio)
			position = position.rotated(rot_angle)
		
		if(move_dir == 1 and angle < 1 or move_dir == -1 and angle > PI - 1):
			var y = position.length()
			var ratio = - move_dir * broadth / (2 * y)
			var rot_angle = - 2 * asin(ratio)
			$RayCast2D.global_position = position.rotated(rot_angle)
			$RayCast2D.rotation = rot_angle
		if(move_dir == 1 and angle < 0.5 or move_dir == -1 and angle > PI - 0.5):
			if(not $RayCast2D.has_overlapping_bodies()):
				paused = true
				await get_tree().create_timer(pause_time).timeout
				paused = false
				move_dir *= -1
			
		for i in range(segment_count):
			var segment_pos_data = calculate_segment_location_and_rotation(i)
			segments[i].position = segment_pos_data.position
			segments[i].rotation = segment_pos_data.rotation
	if check_grounded_delay > 0:
		check_grounded_delay -= delta
	elif not $RayCast2D2.has_overlapping_bodies():
		queue_free()

func calculate_segment_location_and_rotation (i) -> Dictionary:
	var aerial_end_location = Vector2.from_angle(-angle) * broadth
	var gravicenter = (aerial_end_location + Vector2(0, -broadth) + Vector2.ZERO) / 3
	var ax = gravicenter.x
	var ay = gravicenter.y
	var bx = aerial_end_location.x
	var by = aerial_end_location.y
	var cx = 0
	var cy = 0
	var d = 2 * (ax * (by - cy) + bx * (cy - ay) + cx * (ay - by))
	var ux = ((ax * ax + ay * ay) * (by - cy) + (bx * bx + by * by) * (cy - ay) + (cx * cx + cy * cy) * (ay - by)) / d
	var uy = ((ax * ax + ay * ay) * (cx - bx) + (bx * bx + by * by) * (ax - cx) + (cx * cx + cy * cy) * (bx - ax)) / d
	var center = Vector2(ux, uy)
	var radius = center.length()
	var switch_arc_dir = false
	if ux < 0:
		switch_arc_dir = !switch_arc_dir
	if center.angle() > 1:
		switch_arc_dir = !switch_arc_dir
	
	var angle1 = - PI + center.angle()
	var angle2 = - PI + (center-aerial_end_location).angle()
	if(switch_arc_dir):
		angle1 += TAU
	
	if radius < 10000000:
		return {"position": center + radius * Vector2.from_angle((i * angle1 + (segment_count - 1 - i) * angle2)/(segment_count - 1))
		, 	"rotation": (i * angle1 + (segment_count - 1 - i) * angle2)/ (segment_count - 1) + PI/2}
	else:
		return {"position" : Vector2.UP * broadth * i / (segment_count - 1),
			"rotation" : 3 * PI / 2}

func hurt(damage : int, _dir):
	if iframe_time <= 0:
		hp -= damage
		if(hp<=0):
			queue_free()
		else:
			iframe_time = iframes