ime::SceneManager Class Reference

Manages game scenes. More...

#include <SceneManager.h>

Public Types
using	ScenePtr = std::shared_ptr< Scene >

Public Member Functions
void	pushScene (ScenePtr scene, bool enterScene=false)
	Add a Scene. More...
void	popScene ()
	Remove the current active scene. More...
std::size_t	getSceneCount () const
	Get the current number of scenes. More...
void	enterTopScene () const
	Enter the scene at the top of the stack. More...
void	clear ()
	Destroy all scenes. More...
bool	isEmpty () const
	Check if the scene manager is empty or not. More...
void	render (Window &window)
	Render the current scene. More...
void	preUpdate (Time deltaTime)
	Update the scene manager. More...
void	update (Time deltaTime)
	Update the current scene using a variable time step. More...
void	fixedUpdate (Time deltaTime)
	Update the current scene using a fixed time step. More...
void	handleEvent (Event event)
	Handle a system event. More...
void	forEachScene (const Callback< const ScenePtr & > &callback)
	Execute a callback for every scene in the scene manager. More...

Detailed Description

Manages game scenes.

The transition between scenes is managed using the Last In First Out (LIFO) technique (The same way std::stack works). Therefore you cannot transition between scenes at random. The order in which scenes are added to the Engine is important.

For example, if while in the "gameplay" scene, you push a "pause" scene to the game engine, the "gameplay" scene will be paused (onPause called) and the "pause" scene will be entered (onEnter called on the pause scene instance) and the "pause" scene will become the active scene (gets system events, updates and rendered). If you pop the "pause" scene, the engine will destroy it (onExit called on the pause scene instance) and return to the "gameplay" scene (onResume called on the gameplay scene instance). However, if you push (transition to) another scene while in the "pause" scene, the process repeats; the "pause" scene gets paused and the the new scene becomes active)

This class is used internally and it is not meant to be instantiated directly. However, it is available to be used if you want to implement some sort of scene management within a scene (sub scenes within the main scene; maybe instead of having the pause scene as a standalone scene, you make it a sub scene of the gameplay scene. This functionality is not supported in IME. All scenes are standalone and have no knowledge of each other)

Definition at line 66 of file SceneManager.h.

Member Function Documentation

clear()

void ime::SceneManager::clear

(

)

Destroy all scenes.

enterTopScene()

void ime::SceneManager::enterTopScene

(

)

const

Enter the scene at the top of the stack.

This function will enter the last scene to be added and set it as the active scene. This function has no effect if the scene is already entered or the manager has no scenes to manage

fixedUpdate()

void ime::SceneManager::fixedUpdate

(

Time

deltaTime

)

Update the current scene using a fixed time step.

Parameters

deltaTime

Time passed since last update

forEachScene()

void ime::SceneManager::forEachScene

(

const Callback< const ScenePtr & > &

callback

)

Execute a callback for every scene in the scene manager.

Parameters

callback

The callback to be executed

getSceneCount()

std::size_t ime::SceneManager::getSceneCount

(

)

const

Get the current number of scenes.

Returns

The current number of scenes

handleEvent()

void ime::SceneManager::handleEvent

(

Event

event

)

Handle a system event.

Parameters

event

Event to be handled

isEmpty()

bool ime::SceneManager::isEmpty

(

)

const

Check if the scene manager is empty or not.

Returns

True if the scene manager is empty, otherwise false

popScene()

void ime::SceneManager::popScene

(

)

Remove the current active scene.

preUpdate()

void ime::SceneManager::preUpdate

(

Time

deltaTime

)

Update the scene manager.

Parameters

deltaTime

Time passed since last update

This function is called by the engine before event/input handling and scene update takes place

pushScene()

void ime::SceneManager::pushScene	(	ScenePtr	scene,
		bool	enterScene = false
	)

Add a Scene.

Parameters

scene	Scene to be added
enterScene	True to immediately enter the scene or false to delay entry

The scene maybe be added and entered immediately or delayed. By default the scene is delayed. This option allows multiple scenes to be pushed at once to the game engine

for example you may want to add multiple scenes in one frame but only enter the last one first as follows:

sceneManager.pushScene(MainMenu);
sceneManager.pushScene(Loading);
sceneManager.pushScene(Splash, true);
 
// Because of LIFO, the scenes will be arranged in reverse order:
//   Splash -> Loading -> MainMenu.
//
// Because the enter flag is set to true when pushing the "Splash"
// scene, the scene will be added and entered immediately. Let's
// assume that the "Splash" and the "Loading" scenes pop themselves
// from the game engine when ready. The game flow will be as follows:
//
// The "Splash" scene shows for some time then pops/removes itself
// from the game engine, this triggers the engine to check for the
// next available scene. It finds the "Loading" scene and enters it.
// After the "Loading" scene has finished (say, loading some resources),
// it pops/removes itself. This again triggers the engine to check
// for the next available scene, it finds the "MainMenu" scene and
// enters it. From here the user may transition to the "Gameplay"
// or "Quit" scene

Note

A scene can only belong to one scene manager and it cannot be added more than once to the scene manager that owns it

Warning

The pointer must not be null

See also

enterTopScene

render()

void ime::SceneManager::render

(

Window &

window

)

Render the current scene.

Parameters

window

The window to render the scene on

update()

void ime::SceneManager::update

(

Time

deltaTime

)

Update the current scene using a variable time step.

Parameters

deltaTime

Time passed since last update

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The documentation for this class was generated from the following file:

• SceneManager.h