com.artemis.systems

Class DelayedEntityProcessingSystem

java.lang.Object

com.artemis.EntitySystem

com.artemis.systems.DelayedEntityProcessingSystem

All Implemented Interfaces:

EntityObserver

public abstract class DelayedEntityProcessingSystem
extends EntitySystem

The purpose of this class is to allow systems to execute at varying intervals.

An example system would be an ExpirationSystem, that deletes entities after a certain lifetime. Instead of running a system that decrements a timeLeft value for each entity, you can simply use this system to execute in a future at a time of the shortest lived entity, and then reset the system to run at a time in a future at a time of the shortest lived entity, etc.

Another example system would be an AnimationSystem. You know when you have to animate a certain entity, e.g. in 300 milliseconds. So you can set the system to run in 300 ms to perform the animation.

This will save CPU cycles in some scenarios.

Implementation notes:
In order to start the system you need to override the inserted(Entity e) method, look up the delay time from that entity and offer it to the system by using the offerDelay(float delay) method. Also, when processing the entities you must also call offerDelay(float delay) for all valid entities.

Author:

Arni Arent

Field Summary

Fields inherited from class com.artemis.EntitySystem

world

Constructor Summary

Constructors

Constructor and Description
DelayedEntityProcessingSystem(Aspect aspect) Creates a new DelayedEntityProcessingSystem.

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	checkProcessing() Check if the system should be processed.
float	getInitialTimeDelay() Get the initial delay that the system was ordered to process entities after.
protected abstract float	getRemainingDelay(Entity e) Return the delay until this entity should be processed.
float	getRemainingTimeUntilProcessing() Get the time until the system is scheduled to run at.
protected void	inserted(Entity e) Called if the system has received a entity it is interested in, e.g created or a component was added to it.
boolean	isRunning() Check if the system is counting down towards processing.
void	offerDelay(float offeredDelay) Restarts the system only if the delay offered is shorter than the time that the system is currently scheduled to execute at.
protected abstract void	processDelta(Entity e, float accumulatedDelta) Process a entity this system is interested in.
protected void	processEntities(ImmutableBag<Entity> entities) Any implementing entity system must implement this method and the logic to process the given entities of the system.
protected abstract void	processExpired(Entity e)
void	restart(float delay) Deprecated. bugged and unnecessary. don't use.
void	stop() Stops the system from running, aborts current countdown.

Methods inherited from class com.artemis.EntitySystem

added, added, begin, changed, changed, check, deleted, deleted, disabled, dispose, enabled, end, getActives, initialize, isEnabled, isPassive, process, removed, setEnabled, setPassive, setWorld

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DelayedEntityProcessingSystem

public DelayedEntityProcessingSystem(Aspect aspect)

Creates a new DelayedEntityProcessingSystem.

Parameters:

aspect - the aspect to match against entities

Method Detail

processEntities

protected final void processEntities(ImmutableBag<Entity> entities)

Description copied from class: EntitySystem

Any implementing entity system must implement this method and the logic to process the given entities of the system.

Specified by:

processEntities in class EntitySystem

Parameters:

entities - the entities this system contains.

inserted

protected void inserted(Entity e)

Description copied from class: EntitySystem

Called if the system has received a entity it is interested in, e.g created or a component was added to it.

Overrides:

inserted in class EntitySystem

Parameters:

e - the entity that was added to this system

getRemainingDelay

protected abstract float getRemainingDelay(Entity e)

Return the delay until this entity should be processed.

Parameters:

e - entity

Returns:

delay

checkProcessing

protected final boolean checkProcessing()

Description copied from class: EntitySystem

Check if the system should be processed.

Overrides:

checkProcessing in class EntitySystem

Returns:

true if the system should be processed, false if not.

processDelta

protected abstract void processDelta(Entity e,
                float accumulatedDelta)

Process a entity this system is interested in.

Substract the accumulatedDelta from the entities defined delay.

Parameters:

e - the entity to process

accumulatedDelta - the delta time since this system was last executed

processExpired

protected abstract void processExpired(Entity e)

restart

@Deprecated
public void restart(float delay)

Deprecated. bugged and unnecessary. don't use.

Start processing of entities after a certain amount of delta time.

Cancels current delayed run and starts a new one.

Parameters:

delay - time delay until processing starts

offerDelay

public void offerDelay(float offeredDelay)

Restarts the system only if the delay offered is shorter than the time that the system is currently scheduled to execute at.

If the system is already stopped (not running) then the offered delay will be used to restart the system with no matter its value.

If the system is already counting down, and the offered delay is larger than the time remaining, the system will ignore it. If the offered delay is shorter than the time remaining, the system will restart itself to run at the offered delay.

Parameters:

offeredDelay - delay to offer

getInitialTimeDelay

public float getInitialTimeDelay()

Get the initial delay that the system was ordered to process entities after.

Returns:

the originally set delay

getRemainingTimeUntilProcessing

public float getRemainingTimeUntilProcessing()

Get the time until the system is scheduled to run at.

Returns zero (0) if the system is not running. Use isRunning() before checking this value.

Returns:

time when system will run at

isRunning

public boolean isRunning()

Check if the system is counting down towards processing.

Returns:

true if it's counting down, false if it's not running

stop

public void stop()

Stops the system from running, aborts current countdown.

Call offerDelay or restart to run it again.