Scene Management
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 = SceneManager.new{
["menu"] = Menu,
["game"] = Game,
["endScene"] = EndScene,
}
stage:addChild(sceneManager)
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)
end
function MyScene:onEnterEnd()
self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
-- create your timers
-- also you can add your player sprite
-- and so on...
end
function MyScene:onExitBegin()
self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
-- stop your timers
-- save score
-- and so on...
end
PREV.: Classes in Gideros
NEXT: Introduction to Graphics
