@tool
class_name TerrainInstance3D extends GeometryInstance3D

var _mesh := ArrayMesh.new()

var _material: ShaderMaterial = (func ():
	var material := ShaderMaterial.new()

	material.shader = preload("res://terrain_shader.gdshader")

	return material).call()

##
##
##
@export
var size: Vector2i = Vector2i.ZERO:
	get:
		return size

	set(value):
		self._mesh.clear_surfaces()

		var width := value.x
		var height := value.y

		if (width != 0) and (height != 0):
			if (width != size.x) or (height != size.y):
				var surface_tool := SurfaceTool.new()

				surface_tool.begin(Mesh.PRIMITIVE_TRIANGLES)

				var center_x := width / 2.0
				var center_y := height / 2.0

				for y in height + 1:
					for x in width + 1:
						surface_tool.set_uv(Vector2(x / float(width), y / float(height)))
						surface_tool.set_color(Color(0.0, 0.0, 0.0, 0.0))
						surface_tool.set_normal(Vector3.UP)
						surface_tool.add_vertex(Vector3(x - center_x, 0.0, y - center_y))

				var vert := 0

				for y in height:
					for x in width:
						surface_tool.add_index(vert + width + 2)
						surface_tool.add_index(vert + width + 1)
						surface_tool.add_index(vert + 1)
						surface_tool.add_index(vert + 1)
						surface_tool.add_index(vert + width + 1)
						surface_tool.add_index(vert + 0)

						vert += 1

					vert += 1

				RenderingServer.instance_set_base(self.get_instance(),
					surface_tool.commit(self._mesh).get_rid())

				self._material.set_shader_parameter("AREA", Vector2(value))
				self._mesh.surface_set_material(0, self._material)

		size = value

##
##
##
@export
var layer_1_albedo: Texture2D = null:
	get:
		return layer_1_albedo

	set(value):
		self._material.set_shader_parameter("LAYER_1_ALBEDO", value)

		layer_1_albedo = value

##
##
##
@export
var layer_1_normal_map: Texture2D = null:
	get:
		return layer_1_normal_map

	set(value):
		self._material.set_shader_parameter("LAYER_1_NORMAL_MAP", value)

		layer_1_normal_map = value

##
##
##
@export
var layer_2_albedo: Texture2D = null:
	get:
		return layer_2_albedo

	set(value):
		self._material.set_shader_parameter("LAYER_2_ALBEDO", value)

		layer_2_albedo = value

##
##
##
@export
var layer_2_normal_map: Texture2D = null:
	get:
		return layer_2_normal_map

	set(value):
		self._material.set_shader_parameter("LAYER_2_NORMAL_MAP", value)

		layer_2_normal_map = value

##
##
##
@export
var layer_3_albedo: Texture2D = null:
	get:
		return layer_3_albedo

	set(value):
		self._material.set_shader_parameter("LAYER_3_ALBEDO", value)

		layer_3_albedo = value

##
##
##
@export
var layer_3_normal_map: Texture2D = null:
	get:
		return layer_3_normal_map

	set(value):
		self._material.set_shader_parameter("LAYER_3_NORMAL_MAP", value)

		layer_3_normal_map = value

##
##
##
@export
var layer_4_albedo: Texture2D = null:
	get:
		return layer_4_albedo

	set(value):
		self._material.set_shader_parameter("LAYER_4_ALBEDO", value)

		layer_4_albedo = value

##
##
##
@export
var layer_4_normal_map: Texture2D = null:
	get:
		return layer_4_normal_map

	set(value):
		self._material.set_shader_parameter("LAYER_4_NORMAL_MAP", value)

		layer_4_normal_map = value

##
##
##
@export
var terrain_map: Texture2D = null:
	get:
		return terrain_map

	set(value):
		self._material.set_shader_parameter("TERRAIN_MAP", value)

		terrain_map = value

##
##
##
@export
var max_height := 100.0:
	get:
		return max_height

	set(value):
		self._material.set_shader_parameter("MAX_HEIGHT", value)

		max_height = max(value, 0.0)

func _init() -> void:
	RenderingServer.instance_set_base(self.get_instance(), self._mesh)