Class: Zif::Scene Abstract

Inherits:
Object
  • Object
show all
Includes:
Serializable
Defined in:
lib/zif/scene.rb

Overview

This class is abstract.

Subclass and override at least #perform_tick.

A Scene is a full-screen view of your game. The concept is to show one scene at a time.

Each scene in your game should be a subclass of Scene which overrides at least #perform_tick.

Using the structure in Game, #perform_tick comes after input handling and before updating Actions::Actionables.

Your subclass should use #perform_tick to add/remove Clickables/Actions::Actionables, and respond to any detected input. #prepare_scene and #unload_scene will be called before and after scene transition.

Switching scenes is handled in Game, based on the return value of #perform_tick.

Examples:

An example scene:

class OpeningScene < Zif::Scene
  def initialize
    # If OpeningScene is registered by symbol using Zif::Game#register_scene, this initialize will happen each
    # time the game switches to this scene.  Otherwise you could instantiate this scene somewhere and simply
    # return it from another scene's #perform_tick
    @dragon = Zif::Sprite.new # ....
    @hello = Zif::UI::Label.new("Hello World!").tap do |label|
      label.x = 100
      label.y = 100
    end
    @current_scene_tick_count = 0
  end

  def prepare_scene
    # You probably want to remove the things registered with the services when scenes change
    # You can remove items explicitly using #remove_.., but #reset_.. will clear everything
    # You can also do this when a scene is being changed away from, using the #unload_scene method.
    $game.services[:action_service].reset_actionables
    $game.services[:input_service].reset
    $gtk.args.outputs.static_sprites.clear
    $gtk.args.outputs.static_labels.clear

    # Now you can use this to do one-time setup code.
    $game.services[:action_service].register_actionable(@dragon)
    $game.services[:input_service].register_clickable(@dragon)

    # Best practice is to use static outputs, this gives you a lot more performance and there is no need to append
    # to the array inside #perform_tick.
    # The only downside is that you have to manage this list manually.  You can remove sprites at any time in
    # #perform_tick.
    $gtk.args.outputs.static_sprites << @dragon
    $gtk.args.outputs.static_labels << @hello
  end

  def perform_tick
    @current_scene_tick_count += 1
    @hello.text = "Hello World! #{@current_scene_tick_count}"

    # Tell Zif::Game to attempt to switch to the scene registered with the name :rainbow_road after some time
    return :rainbow_road if @current_scene_tick_count > 200
  end
end

See Also:

Instance Method Summary collapse

Methods included from Serializable

#exclude_from_serialize, #inspect, #serialize, #to_s

Instance Method Details

#perform_tick ⇒ Symbol, ...

Your Scene subclass must override this method.

Returns:

  • (Symbol, Zif::Scene, nil) —

    Direction to Game about scene transition.

    nil if we are staying on this scene

    Symbol if one has been registered using Game#register_scene

    Zif::Scene subclass instance to transition directly

See Also:



74
75
76
 
# File 'lib/zif/scene.rb', line 74

def perform_tick
  raise "Zif::Scene#perform_tick: Please override #perform_tick for #{self.class}"
end

#prepare_scene ⇒ void

This method returns an undefined value.

Optional - Your scene can use this for setup code before the scene is displayed. You could register sprites with input service, etc.



81
 
# File 'lib/zif/scene.rb', line 81

def prepare_scene; end

#unload_scene ⇒ void

This method returns an undefined value.

Optional - Your scene can use this for tear-down code when the scene is being transitioned away. You could reset input service clickables, etc



86
 
# File 'lib/zif/scene.rb', line 86

def unload_scene; end