path: root/game/src/GameSession/MapView.gd

extends Node3D

signal province_selected(index : int)
signal map_view_camera_changed(near_left : Vector2, far_left : Vector2, far_right : Vector2, near_right : Vector2)

const _action_north : StringName = &"map_north"
const _action_east : StringName = &"map_east"
const _action_south : StringName = &"map_south"
const _action_west : StringName = &"map_west"
const _action_zoom_in : StringName = &"map_zoom_in"
const _action_zoom_out : StringName = &"map_zoom_out"
const _action_drag : StringName = &"map_drag"
const _action_click : StringName = &"map_click"

const _shader_param_province_index : StringName = &"province_index_tex"
const _shader_param_province_colour : StringName = &"province_colour_tex"
const _shader_param_hover_index : StringName = &"hover_index"
const _shader_param_selected_index : StringName = &"selected_index"
const _shader_param_terrain_tile_factor : StringName = &"terrain_tile_factor"

@export var _camera : Camera3D

@export var _cardinal_move_speed : float = 1.0
@export var _edge_move_threshold: float = 0.01
@export var _edge_move_speed: float = 2.5
var _drag_anchor : Vector2
var _drag_active : bool = false

var _mouse_over_viewport : bool = true

@export var _zoom_target_min : float = 0.05
@export var _zoom_target_max : float = 5.0
@export var _zoom_target_step : float = 0.1
@export var _zoom_epsilon : float = _zoom_target_step * 0.1
@export var _zoom_speed : float = 5.0
@export var _zoom_target : float = 1.0:
   get: return _zoom_target
   set(v): _zoom_target = clamp(v, _zoom_target_min, _zoom_target_max)

@export var _map_mesh_instance : MeshInstance3D
var _map_mesh : MapMesh
var _map_shader_material : ShaderMaterial
var _map_image_size : Vector2
var _map_province_index_image : Image
var _map_province_colour_image : Image
var _map_province_colour_texture : ImageTexture
var _map_mesh_corner : Vector2
var _map_mesh_dims : Vector2

var _mouse_pos_viewport : Vector2 = Vector2(0.5, 0.5)
var _mouse_pos_map : Vector2 = Vector2(0.5, 0.5)
var _viewport_dims : Vector2 = Vector2(1, 1)

# ??? Strange Godot/GDExtension Bug ???
# Upon first opening a clone of this repo with the Godot Editor,
# if GameSingleton.get_province_index_image is called before MapMesh
# is referenced in the script below, then the editor will crash due
# to a failed HashMap lookup. I'm not sure if this is a bug in the
# editor, GDExtension, my own extension, or a combination of them.
# This was an absolute pain to track down. --- hop311
func _ready():
   if _camera == null:
      push_error("MapView's _camera variable hasn't been set!")
      return
   _zoom_target = _camera.position.y
   if _map_mesh_instance == null:
      push_error("MapView's _map_mesh variable hasn't been set!")
      return

   # Shader Material
   var map_material := _map_mesh_instance.get_active_material(0)
   if map_material == null:
      push_error("Map mesh is missing material!")
      return
   if not map_material is ShaderMaterial:
      push_error("Invalid map mesh material class: ", map_material.get_class())
      return
   _map_shader_material = map_material

   # Province index texture
   _map_province_index_image = GameSingleton.get_province_index_image()
   if _map_province_index_image == null:
      push_error("Failed to get province index image!")
      return
   var province_index_texture := ImageTexture.create_from_image(_map_province_index_image)
   _map_shader_material.set_shader_parameter(_shader_param_province_index, province_index_texture)

   # Province colour texture
   _map_province_colour_image = GameSingleton.get_province_colour_image()
   if _map_province_colour_image == null:
      push_error("Failed to get province colour image!")
      return
   _map_province_colour_texture = ImageTexture.create_from_image(_map_province_colour_image)
   _map_shader_material.set_shader_parameter(_shader_param_province_colour, _map_province_colour_texture)

   if not _map_mesh_instance.mesh is MapMesh:
      push_error("Invalid map mesh class: ", _map_mesh_instance.mesh.get_class(), "(expected MapMesh)")
      return
   _map_mesh = _map_mesh_instance.mesh

   # Set map mesh size and get bounds
   _map_image_size = Vector2(Vector2i(GameSingleton.get_width(), GameSingleton.get_height()))
   _map_mesh.aspect_ratio = _map_image_size.x / _map_image_size.y
   _map_shader_material.set_shader_parameter(_shader_param_terrain_tile_factor, _map_image_size.y / 64.0)
   var map_mesh_aabb := _map_mesh.get_core_aabb() * _map_mesh_instance.transform
   _map_mesh_corner = Vector2(
      min(map_mesh_aabb.position.x, map_mesh_aabb.end.x),
      min(map_mesh_aabb.position.z, map_mesh_aabb.end.z)
   )
   _map_mesh_dims = abs(Vector2(
      map_mesh_aabb.position.x - map_mesh_aabb.end.x,
      map_mesh_aabb.position.z - map_mesh_aabb.end.z
   ))

func _notification(what : int):
   match what:
      NOTIFICATION_WM_MOUSE_ENTER: # Mouse inside window
         _on_mouse_entered_viewport()
      NOTIFICATION_WM_MOUSE_EXIT: # Mouse out of window
         _on_mouse_exited_viewport()

func _update_colour_texture() -> void:
   GameSingleton.update_colour_image()
   _map_province_colour_texture.update(_map_province_colour_image)

func _world_to_map_coords(pos : Vector3) -> Vector2:
   return (Vector2(pos.x, pos.z) - _map_mesh_corner) / _map_mesh_dims

func _viewport_to_map_coords(pos_viewport : Vector2) -> Vector2:
   var ray_origin := _camera.project_ray_origin(pos_viewport)
   var ray_normal := _camera.project_ray_normal(pos_viewport)
   # Plane with normal (0,1,0) facing upwards, at a distance 0 from the origin
   var intersection = Plane(0, 1, 0, 0).intersects_ray(ray_origin, ray_normal)
   if typeof(intersection) == TYPE_VECTOR3:
      return _world_to_map_coords(intersection as Vector3)
   else:
      # Normals parallel to the xz-plane could cause null intersections,
      # but the camera's orientation should prevent such normals
      push_error("Invalid intersection: ", intersection)
      return Vector2(0.5, 0.5)

func zoom_in() -> void:
   _zoom_target -= _zoom_target_step

func zoom_out() -> void:
   _zoom_target += _zoom_target_step

# REQUIREMENTS
# * SS-31
func _unhandled_input(event : InputEvent):
   if _mouse_over_viewport and event.is_action_pressed(_action_click):
      # Check if the mouse is outside of bounds
      if _map_mesh.is_valid_uv_coord(_mouse_pos_map):
         var selected_index := GameSingleton.get_province_index_from_uv_coords(_mouse_pos_map)
         _map_shader_material.set_shader_parameter(_shader_param_selected_index, selected_index)
         province_selected.emit(selected_index)
      else:
         print("Clicked outside the map!")
   elif event.is_action_pressed(_action_drag):
      if _drag_active:
         push_warning("Drag being activated while already active!")
      _drag_active = true
      _drag_anchor = _mouse_pos_map
   elif event.is_action_released(_action_drag):
      if not _drag_active:
         push_warning("Drag being deactivated while already not active!")
      _drag_active = false
   elif event.is_action_pressed(_action_zoom_in, true):
      zoom_in()
   elif event.is_action_pressed(_action_zoom_out, true):
      zoom_out()

func _physics_process(delta : float):
   _mouse_pos_viewport = get_viewport().get_mouse_position()
   _viewport_dims = Vector2(Resolution.get_current_resolution())
   # Process movement
   _movement_process(delta)
   # Keep within map bounds
   _clamp_over_map()
   # Process zooming
   _zoom_process(delta)
   # Orient based on height
   _update_orientation()
   # Update viewport on minimap
   _update_minimap_viewport()
   # Calculate where the mouse lies on the map
   _update_mouse_map_position()

# REQUIREMENTS
# * UIFUN-124
func _movement_process(delta : float) -> void:
   var direction : Vector2
   if _drag_active:
      direction = (_drag_anchor - _mouse_pos_map) * _map_mesh_dims
   else:
      direction = _edge_scrolling_vector() + _cardinal_movement_vector()
      # Scale movement speed with height
      direction *= _camera.position.y * delta
   _camera.position += Vector3(direction.x, 0, direction.y)

# REQUIREMENTS
# * UIFUN-125
func _edge_scrolling_vector() -> Vector2:
   if not _mouse_over_viewport:
      return Vector2()
   var mouse_vector := _mouse_pos_viewport / _viewport_dims - Vector2(0.5, 0.5)
   if abs(mouse_vector.x) < 0.5 - _edge_move_threshold and abs(mouse_vector.y) < 0.5 - _edge_move_threshold:
      mouse_vector *= 0
   return mouse_vector * _edge_move_speed

# REQUIREMENTS
# * SS-75
func _cardinal_movement_vector() -> Vector2:
   var move := Vector2(
      float(Input.is_action_pressed(_action_east)) - float(Input.is_action_pressed(_action_west)),
      float(Input.is_action_pressed(_action_south)) - float(Input.is_action_pressed(_action_north))
   )
   return move * _cardinal_move_speed

func _clamp_over_map() -> void:
   _camera.position.x = _map_mesh_corner.x + fposmod(_camera.position.x - _map_mesh_corner.x, _map_mesh_dims.x)
   _camera.position.z = clamp(_camera.position.z, _map_mesh_corner.y, _map_mesh_corner.y + _map_mesh_dims.y)

# REQUIREMENTS
# * SS-74
# * UIFUN-123
func _zoom_process(delta : float) -> void:
   var height := _camera.position.y
   var zoom := _zoom_target - height
   height += zoom * _zoom_speed * delta
   var new_zoom := _zoom_target - height
   # Set to target if height is within _zoom_epsilon of it or has overshot past it
   if abs(new_zoom) < _zoom_epsilon or sign(zoom) != sign(new_zoom):
      height = _zoom_target
   _camera.position.y = height

func _update_orientation() -> void:
   var dir := Vector3(0, -1, -exp(-_camera.position.y - 1))
   _camera.look_at(_camera.position + dir)

func _update_minimap_viewport() -> void:
   var near_left := _viewport_to_map_coords(Vector2(0, _viewport_dims.y))
   var far_left := _viewport_to_map_coords(Vector2(0, 0))
   var far_right := _viewport_to_map_coords(Vector2(_viewport_dims.x, 0))
   var near_right := _viewport_to_map_coords(_viewport_dims)
   map_view_camera_changed.emit(near_left, far_left, far_right, near_right)

func _update_mouse_map_position() -> void:
   _mouse_pos_map = _viewport_to_map_coords(_mouse_pos_viewport)
   var hover_index := GameSingleton.get_province_index_from_uv_coords(_mouse_pos_map)
   if _mouse_over_viewport:
      _map_shader_material.set_shader_parameter(_shader_param_hover_index, hover_index)

func _on_mouse_entered_viewport():
   _mouse_over_viewport = true

func _on_mouse_exited_viewport():
   _mouse_over_viewport = false

func _on_minimap_clicked(pos_clicked : Vector2):
   pos_clicked *= _map_mesh_dims
   _camera.position.x = pos_clicked.x
   _camera.position.z = pos_clicked.y
   _clamp_over_map()

func enable_processing() -> void:
   set_process_unhandled_input(true)
   set_physics_process(true)

func disable_processing() -> void:
   set_process_unhandled_input(false)
   set_physics_process(false)