extends Node3D

@export var tree: Mesh
@export var leaves: Mesh
@export var noise: Noise
@export var size_x: float
@export var size_z: float
@export var step: float = 1
@export var density: float
@export var position_randomness := 1.0

const TILE_SIZE := 10

func _ready():
	if !visible:
		return

	var total_count := 0
	var tile_count := 0

	var old_tile_x := NAN
	var old_tile_z := NAN

	var offsets: Array[Vector3] = []

	for x in range(-size_x, size_x, step):
		for z in range(-size_z, size_z, step):
			if noise.get_noise_2d(x, z) < 1 - density * 2:
				continue
			
			var tile_x := x / TILE_SIZE
			var tile_z := z / TILE_SIZE

			if tile_x != old_tile_x || tile_z != old_tile_z:
				if tile_count > 0:
					var tile := make_tile(old_tile_x, old_tile_z)
					tile.multimesh.instance_count = tile_count
					tile.multimesh.visible_instance_count = tile_count

					for i in range(tile_count):
						tile.multimesh.set_instance_transform(i, Transform3D(Basis(), offsets[i] - tile.position))
					
					add_child(tile)

					var tile2 := make_tile(old_tile_x, old_tile_z)
					tile2.multimesh.mesh = leaves
					tile2.multimesh.instance_count = tile_count
					tile2.multimesh.visible_instance_count = tile_count

					for i in range(tile_count):
						tile2.multimesh.set_instance_transform(i, Transform3D(Basis(), offsets[i] - tile.position))
					
					add_child(tile2)

					tile_count = 0
					offsets.resize(0)

			old_tile_x = tile_x
			old_tile_z = tile_z
			
			var offset := Vector3.ZERO
			offset.x = x + (randf() - 0.5) * position_randomness
			offset.z = z + (randf() - 0.5) * position_randomness
			offsets.append(offset)

			tile_count += 1
			total_count += 1
	
	print("Generated %d trees" % total_count)

func make_tile(x, z) -> MultiMeshInstance3D:
	prints("Tile:", x * TILE_SIZE, z * TILE_SIZE)

	var instance := MultiMeshInstance3D.new()
	instance.multimesh = MultiMesh.new()
	instance.multimesh.mesh = tree
	instance.multimesh.transform_format = MultiMesh.TRANSFORM_3D
	
	var safe_area := Vector3(0, 0, 0)
	instance.position = Vector3(x * TILE_SIZE, 0, z * TILE_SIZE)
	instance.custom_aabb.position = -safe_area
	instance.custom_aabb.size = Vector3(TILE_SIZE, 30, TILE_SIZE) + safe_area * 2
	return instance