@tool
extends Node3D
# Киберпанк-птицы кружат вокруг цели. Один MultiMesh, взмахи крыльев считает шейдер.

@export var target_path: NodePath

var target: Node3D
@export var count := 12
@export var min_radius := 55.0
@export var max_radius := 100.0
@export var min_height := 15.0
@export var max_height := 150.0
@export var speed_range := Vector2(0.15, 0.35)  # рад/с вокруг цели
@export var bird_scale := 1.6
@export var seed_value := 7

const SHADER := """
shader_type spatial;
render_mode cull_disabled, unshaded, fog_disabled;
uniform float flap_speed = 9.0;
uniform float flap_amp = 0.9;
varying vec3 col;
void vertex() {
	float ph = INSTANCE_CUSTOM.x;
	// COLOR.r — вес крыла (0 у тела, 1 на кончике)
	VERTEX.y += sin(TIME * flap_speed * (0.8 + INSTANCE_CUSTOM.y * 0.4) + ph) * flap_amp * COLOR.r;
	VERTEX.z += COLOR.r * 0.25 * cos(TIME * flap_speed + ph);
	col = INSTANCE_CUSTOM.z > 0.5 ? vec3(1.0, 0.1, 0.8) : vec3(0.0, 0.95, 1.0);
}
void fragment() {
	// Светлее к кончикам крыльев — HDR для свечения
	ALBEDO = col * (5.0 + 3.0 * COLOR.r);
}
"""

var _mm: MultiMesh
var _orbit: Array[Dictionary] = []

func _ready() -> void:
	target = get_node_or_null(target_path) as Node3D
	_build()

func _build() -> void:
	var rng := RandomNumberGenerator.new()
	rng.seed = seed_value

	var mat := ShaderMaterial.new()
	var sh := Shader.new()
	sh.code = SHADER
	mat.shader = sh

	_mm = MultiMesh.new()
	_mm.transform_format = MultiMesh.TRANSFORM_3D
	_mm.use_custom_data = true
	_mm.mesh = _make_mesh()
	_mm.mesh.surface_set_material(0, mat)
	_mm.instance_count = count
	for i in count:
		_orbit.append({
			"r": rng.randf_range(min_radius, max_radius),
			"h": rng.randf_range(min_height, max_height),
			"w": rng.randf_range(speed_range.x, speed_range.y) * (1.0 if rng.randf() > 0.3 else -1.0),
			"a": rng.randf() * TAU,
			"bob": rng.randf() * TAU,
		})
		_mm.set_instance_custom_data(i, Color(rng.randf() * TAU, rng.randf(), 1.0 if rng.randf() < 0.3 else 0.0, 0.0))

	var mmi := MultiMeshInstance3D.new()
	mmi.name = "Flock"
	mmi.multimesh = _mm
	mmi.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	mmi.custom_aabb = AABB(Vector3(-400, -50, -400), Vector3(800, 400, 800))
	mmi.top_level = true  # координаты глобальные
	add_child(mmi)
	_update(0.0)

# Угловатая птица: тело-ромб, хвост и два крыла-«клинка» (вес крыла в цвете вершины)
func _make_mesh() -> ArrayMesh:
	var st := SurfaceTool.new()
	st.begin(Mesh.PRIMITIVE_TRIANGLES)
	var tris := [
		# [вершина, вес крыла]
		# тело (носом в -Z)
		[Vector3(0, 0, -1.2), 0.0], [Vector3(-0.25, 0, 0.3), 0.0], [Vector3(0.25, 0, 0.3), 0.0],
		[Vector3(0, 0.2, 0.0), 0.0], [Vector3(-0.25, 0, 0.3), 0.0], [Vector3(0, 0, -1.2), 0.0],
		[Vector3(0, 0.2, 0.0), 0.0], [Vector3(0, 0, -1.2), 0.0], [Vector3(0.25, 0, 0.3), 0.0],
		# хвост
		[Vector3(-0.2, 0, 0.3), 0.0], [Vector3(0, 0, 1.4), 0.0], [Vector3(0.2, 0, 0.3), 0.0],
		# левое крыло
		[Vector3(-0.2, 0, -0.5), 0.0], [Vector3(-2.6, 0, 0.5), 1.0], [Vector3(-0.2, 0, 0.4), 0.0],
		# правое крыло
		[Vector3(0.2, 0, -0.5), 0.0], [Vector3(0.2, 0, 0.4), 0.0], [Vector3(2.6, 0, 0.5), 1.0],
	]
	for t in tris:
		st.set_color(Color(t[1], 0, 0))
		st.add_vertex(t[0])
	return st.commit()

func _process(delta: float) -> void:
	_update(delta)

func _update(delta: float) -> void:
	if _mm == null or target == null:
		return
	var c := target.global_position
	var t := Time.get_ticks_msec() * 0.001
	for i in _orbit.size():
		var o: Dictionary = _orbit[i]
		o["a"] += o["w"] * delta
		var a: float = o["a"]
		var pos := c + Vector3(cos(a) * o["r"], o["h"] + sin(t * 0.7 + o["bob"]) * 3.0, sin(a) * o["r"])
		# Летим по касательной, лёгкий крен в сторону поворота
		var dir := Vector3(-sin(a), 0, cos(a)) * signf(o["w"])
		var b := Basis.looking_at(dir, Vector3.UP)
		b = b.rotated(dir, -0.35 * signf(o["w"])).scaled(Vector3.ONE * bird_scale)
		_mm.set_instance_transform(i, Transform3D(b, pos))