单向平台

extends Node

const SPEED: float = 320.0
const JUMP_VELOCITY: float = -900.0
const GRAVITY: float = 1600.0
const BODY_SIZE: Vector2 = Vector2(42, 60)

var player: CharacterBody2D
var start: Vector2


func _ready() -> void:
	_add_background()

	var view: Vector2 = get_viewport().get_visible_rect().size

	_add_platform(Vector2(view.x * 0.5, view.y - 30), Vector2(view.x, 60), false)
	_add_platform(Vector2(view.x * 0.5, view.y - 220), Vector2(340, 22), true)
	_add_platform(Vector2(view.x * 0.5, view.y - 400), Vector2(240, 22), true)

	start = Vector2(view.x * 0.5, view.y - 120)
	player = _add_player(start)

	print('a and d to move, space to jump, the thin platforms let you pass from below')


func _physics_process(delta: float) -> void:
	player.velocity.y += GRAVITY * delta

	if player.is_on_floor() and Input.is_key_pressed(KEY_SPACE):
		player.velocity.y = JUMP_VELOCITY

	player.velocity.x = (float(Input.is_key_pressed(KEY_D)) - float(Input.is_key_pressed(KEY_A))) * SPEED
	player.move_and_slide()

	if player.position.y > get_viewport().get_visible_rect().size.y + 200:
		player.position = start
		player.velocity = Vector2.ZERO


func _add_player(at: Vector2) -> CharacterBody2D:
	var shape: RectangleShape2D = RectangleShape2D.new()
	shape.size = BODY_SIZE

	var collision: CollisionShape2D = CollisionShape2D.new()
	collision.shape = shape

	var body: CharacterBody2D = CharacterBody2D.new()
	body.position = at
	body.add_child(_make_rect(BODY_SIZE, Color('#8eef97')))
	body.add_child(collision)
	add_child(body)

	return body


func _add_platform(center: Vector2, size: Vector2, one_way: bool) -> void:
	var shape: RectangleShape2D = RectangleShape2D.new()
	shape.size = size

	var collision: CollisionShape2D = CollisionShape2D.new()
	collision.shape = shape
	collision.one_way_collision = one_way

	var platform: StaticBody2D = StaticBody2D.new()
	platform.position = center
	platform.add_child(_make_rect(size, Color('#8da5f3') if one_way else Color('#2a2f3d')))
	platform.add_child(collision)
	add_child(platform)


func _make_rect(size: Vector2, color: Color) -> Polygon2D:
	var rect: Polygon2D = Polygon2D.new()
	rect.polygon = PackedVector2Array([-size * 0.5, Vector2(size.x, -size.y) * 0.5, size * 0.5, Vector2(-size.x, size.y) * 0.5])
	rect.color = color

	return rect


func _add_background() -> void:
	var background: ColorRect = ColorRect.new()
	background.color = Color('#12141a')
	add_child(background)
	background.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)