DragonRuby Game Toolkit - Scene Management With Fade To Black

main.rb

class RootScene < Scene
  attr :game

  def initialize
    @game = Game.new
    $game = @game
    @world_scene = WorldScene.new
    @embark_scene = EmbarkScene.new
    @world_event_scene = WorldEventScene.new
    @battle_scene = BattleScene.new
    @game_over_scene = GameOverScene.new
    @loot_scene = LootScene.new
    @cutscene_scene = CutsceneScene.new
    @alert_scene = AlertScene.new
    @mini_world_scene = MiniWorldScene.new
    @mini_world_event_scene = MiniWorldEventScene.new
    @mini_world_loot_scene = MiniWorldLootScene.new
    $root_scene = self
  end

  def defaults
    state.scene ||= :embark_scene
    state.scene_at ||= 0
    state.fade_at ||= 0
  end

  def bg_prefab
    { x: Grid.allscreen_x,
      y: Grid.allscreen_y,
      w: Grid.allscreen_w,
      h: Grid.allscreen_h,
      path: :solid,
      r: 255,
      g: 255,
      b: 255,
      a: 255 }
  end

  def fade_prefab
    start_time = state.fade_at
    duration = 30
    spline = [
      [  0, 0.25, 0.75, 1.0],
      [1.0, 0.75, 0.25,   0]
    ]

    if Kernel.tick_count < 15
      current_progress = 1
    else
      current_progress = Easing.ease_spline(start_time, Kernel.tick_count, duration, spline)
    end

    a = 255 * current_progress
    { x: Grid.allscreen_x,
      y: Grid.allscreen_y,
      w: Grid.allscreen_w,
      h: Grid.allscreen_h,
      path: :solid,
      r: 0,
      g: 0,
      b: 0,
      a: a }
  end

  def tick
    defaults

    inputs.clear if state.queued_scene

    scene_before_tick = state.scene

    outputs.background_color = [0, 0, 0]
    outputs.primitives << bg_prefab

    scene_tick

    outputs.primitives << fade_prefab

    if state.scene != scene_before_tick
      raise "Scene change is not allowed during tick, set next_scene instead"
    end

    if state.next_scene
      if state.queued_scene
        state.next_scene = nil
        state.next_scene_metadata = nil
      else
        state.queued_scene = state.next_scene
        state.queued_scene_at = Kernel.tick_count
        state.queued_scene_metadata = state.next_scene_metadata
        state.queued_scene_callback = state.next_scene_callback
        state.next_scene = nil
        state.fade_at = Kernel.tick_count
      end
    end

    if state.queued_scene_at && state.queued_scene_at.elapsed_time >= 15 && state.queued_scene
      state.scene = state.queued_scene
      state.scene_at = Kernel.tick_count
      state.scene_metadata = state.queued_scene_metadata
      state.queued_scene_callback.call if state.queued_scene_callback
      state.queued_scene = nil
      state.queued_scene_at = nil
      state.queued_scene_metadata = nil
      state.queued_scene_callback = nil
    end
  end

  def scenes
    [
      @embark_scene,
      @world_scene,
      @world_event_scene,
      @battle_scene,
      @game_over_scene,
      @loot_scene,
      @cutscene_scene,
      @alert_scene,
      @mini_world_scene,
      @mini_world_event_scene,
      @mini_world_loot_scene
    ]
  end

  def scene_current
    scenes.find { |s| s.id == state.scene }
  end

  def scene_set_args
    scene = scene_current

    if !scene
      raise "Scene with id of #{state.scene} was not found."
    end

    scene.game = @game
    scene.args = args
    scene.metadata = state.scene_metadata || {}
    $scene = scene_current
  end

  def scene_tick
    scene_set_args

    if state.scene_at == Kernel.tick_count - 1
      scene_current.will_appear
    end

    scene_current.tick
  end
end