extends CharacterBody3D
class_name Fragment

@export var sub: PackedScene
@export var gravity_scale: float = 1.0
@export var alive_time: float = 1.0

var velocity_min: Vector2 = Vector2(0, 2)
var velocity_max: Vector2 = Vector2(2, 4)

@onready var sprite3D: Sprite3D = %Sprite3D as Sprite3D

var gravity                  = ProjectSettings.get_setting("physics/3d/default_gravity")
var frame_rate: float        = 0.1
var frame_time: float        = 0
var fade_out_treshold: float = 0.5


func _ready():
	var dir: Vector2 = Util.angle_dir(randf_range(0, 360)) * randf_range(velocity_min.x, velocity_max.x)
	velocity.x = dir.x
	velocity.z = dir.y
	velocity.y = randf_range(velocity_min.y, velocity_max.y)
	alive_time += randf_range(0, 0.5)


func _process(delta: float) -> void:
	velocity.y -= gravity * gravity_scale * delta
	if velocity.length() > 0.01:
		var frame_count: int      = sprite3D.hframes * sprite3D.vframes
		var frame_time_all: float = frame_rate * frame_count
		frame_time += delta
		sprite3D.frame = int(frame_time / frame_rate) % frame_count
		frame_time = fmod(frame_time, frame_time_all)
	move_and_slide()
	var collision_count: int = get_slide_collision_count()
	if collision_count > 0:
		var normal: Vector3 = Vector3.ZERO
		for i in collision_count:
			var collision: KinematicCollision3D = get_slide_collision(i)
			normal += collision.get_normal()
		normal = normal.normalized()
		if sub:
			Global.effect_mgr.cast_particle(sub, global_position, normal)
			queue_free()
		#反弹
		velocity = (velocity - normal * velocity.dot(normal)) * 0.8
	alive_time -= delta
	if alive_time < fade_out_treshold:
		sprite3D.modulate.a = alive_time / fade_out_treshold
	if alive_time <= 0:
		queue_free()