State Machine

final class State Machine

Extends: N/A

Implements: N/A

Constructor:

Type	Parameter	Description
Time	referenceTime	Engine's physics clock
Boolean	launchOnStart	on startup, will play simulation (run state) if true, else will not play simulation (editor state)

Events

Accessibility	Type	Variable Name	Description
public, static	String	onSaveStateInfo	alert when a save point has been reached
public, static	Boolean	onStateMachineStateChange	alert when the state is changed

Fields:

Accessibility	Type	Field Name	Description
public	State	currentState	System state object controlling response to update loop
public	List	allObjects	objects that are added to the physics loop
public, static	Time	timer	Reference to the simulation engine's physics timer

Methods

Accessibility	Return Type	Method Name	Description
public	void	addEntityToList	adds an entity to objects to be updated in the physics loop
public	void	removeEntityFromList	removes an entity from objects to be updated in the physics loop
public	void	cycle	reverses the allObjects list
public	void	selectEntityWithTag	findObjectWithTag, and set this entity as "selected"
private	void	findObjectWithTag	Return the first entity with the tag specified.
public	void	changeState	move to a new state, given as input to this function.
public	void	handleSimulationToggle	manages state changes and actions when receiving input regarding simulation start/stop
public	void	clearStateMachine	removes all objects from state machine with exception of permanent objects (Settings, Camera)
public	void	loadModel	load a preset model to the simulation using ModelLoader.
public	void	deactivate	Closes major events and clears all simulation objects. Only called prior to shutdown.

State Machine and State Pattern for Data Management

States and Changing State

A state simply manages what actions will be performed during the update loop of the state machine. This way, we can easily control the program logic without having to make a cumbersome number of conditional statements. Additionally, this pattern makes the program more scalable, allowing for additional states to be created if necessary while limiting the amount of rewriting to be done to other scripts.

Simulation Timer and the Update Loop

In conjunction with the Entity class and methods, the simulation updates according to the fps set in the State Machine/ Engine timer. The diagram below shows the relationship between the object function calls, timing, and the update loop.

The Update Loop: As described in the Engine class, the timer "ticks" periodically as determined by the frames per second (fps) variable as set by the user when creating a "Time" timer object. When each of these "ticks" occurs, this leads to the state machine, and eventually the state, calling tick as well. From there, any function within tick will be called (specifically looped over objects in the allObjects list), thus leading to repeated, periodic actions being performed by objects in the state machine. This behavior typically only occurs in the Run State, check the documentation here for more specific descriptions on how this is managed.