Scene Management

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Revision as of 17:37, 15 February 2023 by Pie (talk | contribs) (updated gideros.class(Sprite) as Core.class(Sprite))

The Ultimate Guide to Gideros Studio

Scene Management

Creating game flow and logic

Most applications and games have different scenes (e.g., menu, scoreboard, game levels, inventory, end-of-game, etc). A transition from one scene to another is usually started by user input or some other event. These transitions typically consist of the following steps:

   • Construct the new scene (e.g., load bitmaps, sprites, sounds)
   • Hide the original scene and show the new scene, often with some kind of special effect (e.g., crossfading)
   • Destroy the old scene

Luckily, a "Scene Manager" library is provided directly in Gideros. :-)

Scene Manager Usage Overview

Create a class for each of your scenes (and preferably put them into separate .lua files):

Menu = Core.class(Sprite)
Game = Core.class(Sprite)
EndScene = Core.class(Sprite)

Create a SceneManager instance passing a table with scene names as keys and your classes as values:

local sceneManager ={
   ["menu"] = Menu,
   ["game"] = Game,
   ["endScene"] = EndScene,

Change between scenes with function SceneManager:changeScene(sceneName, duration, transition, ease) like so:

sceneManager:changeScene("game", 1, SceneManager.moveFromTop, easing.linear)

SceneManager dispatches events as it makes the transition from one scene to another (enterBegin, enterEnd, exitBegin, exitEnd). You can register to listen for these events to begin/end your animations, clear your timers, save the scores, etc.

Built-in Transition Effects

The scene manager library defines the following transition effects: Move functions

   • SceneManager.moveFromLeft
   • SceneManager.moveFromRight
   • SceneManager.moveFromBottom
   • SceneManager.moveFromTop
   • SceneManager.moveFromLeftWithFade
   • SceneManager.moveFromRightWithFade
   • SceneManager.moveFromBottomWithFade
   • SceneManager.moveFromTopWithFade

Overlay functions

   • SceneManager.overFromLeft
   • SceneManager.overFromRight
   • SceneManager.overFromBottom
   • SceneManager.overFromTop
   • SceneManager.overFromLeftWithFade
   • SceneManager.overFromRightWithFade
   • SceneManager.overFromBottomWithFade
   • SceneManager.overFromTopWithFade

Fade & flip functions

   • SceneManager.fade
   • SceneManager.crossFade
   • SceneManager.flip
   • SceneManager.flipWithFade
   • SceneManager.flipWithShade

Transition Events

The scene manager dispatches the following four events:

   • enterBegin: Dispatched when your new scene is about to enter the stage. You can initialize your variables here.
   • enterEnd: Dispatched after the transition of new scene has ended. Mostly, you add listeners and start your logic here.
   • exitBegin: Dispatched when your current scene is about to leave the stage. You can remove listeners and stop timers here.
   • exitEnd: Dispatched after your current scene has left the stage.

The following code shows an example scene (“MyScene”) and how you might use the “enterEnd” and “exitBegin” events:

MyScene = Core.class(Sprite)
function MyScene:init()
	self:addEventListener("enterEnd", self.onEnterEnd, self)
	self:addEventListener("exitBegin", self.onExitBegin, self)
function MyScene:onEnterEnd()
	self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
	-- create your timers
	-- also you can add your player sprite
	-- and so on...
function MyScene:onExitBegin()
	self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
	-- stop your timers
	-- save score
	-- and so on...

PREV.: Classes in Gideros
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