extends Node2D

@export var render_width: int = 1920
@export var render_height: int = 1080

@export var decay_factor: float = 0.95

@onready var view := $View
@onready var pass_viewport := $SubViewport
@onready var pass2_viewport := $SubViewport2
@onready var agent_shader: ShaderMaterial = $SubViewport/Pass.material
@onready var trail_shader: ShaderMaterial = $SubViewport2/Pass.material

const MAX_TEXTURES: int = 2
var next_texture: int = 0
var frame_count: int = 0


func _ready():
	RenderingServer.call_on_render_thread(_initialize_render.bind(render_width, render_height))


func _process(_delta: float) -> void:
	next_texture = (next_texture + 1) % MAX_TEXTURES
	RenderingServer.call_on_render_thread(
		_render_process.bind(next_texture, frame_count, decay_factor)
	)

	frame_count = frame_count + 1


# Below is for rendering

var rd: RenderingDevice = null
var sim_texture: Texture2D = null


func _create_initial_sim_texture(width: int, height: int) -> ImageTexture:
	var sim_image := Image.create_empty(width, height, false, Image.FORMAT_RGBF)
	sim_texture = ImageTexture.create_from_image(sim_image)

	return sim_texture


func _initialize_render(width: int, height: int) -> void:
	rd = RenderingServer.get_rendering_device()

	trail_shader.set_shader_parameter("sim_texture", pass_viewport.get_texture().get_rid())
	trail_shader.set_shader_parameter("decay_factor", decay_factor)


func _render_process(next_texture: int, frame_count: int, decay_factor: float) -> void:
	if frame_count > 0:
		agent_shader.set_shader_parameter("sim_texture", pass2_viewport.get_texture().get_rid())

	trail_shader.set_shader_parameter("decay_factor", decay_factor)
	trail_shader.set_shader_parameter("sim_texture", pass_viewport.get_texture().get_rid())
	# agent_shader.set_shader_parameter("sim_texture", pass2_viewport.get_texture().get_rid())