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| JavaECS | docs | entity | EntityManager.md
Entity Manager
| In this Section |
|---|
| About |
| Implementation |
| Constructors |
| Methods |
| Fields |
| Examples |
| Notes |
About
Controls adding and removing entities, and registration and unregistration of components to specific entities.
Implementation
Before attempting to use a system, it must be registered.
Registration requires a call to registerSystem(String systemName, ECSSystem system), with params of the String name and a object reference of the ECSSystem. Using the object reference, a system can be invoked at any time.
Constructors
protected EntityManager(){}
The default constructor initialises unusedEntities to a new queue containing maxSize (1024) unique integers.
protected EntityManager(int maxEntities){}
Initialises unusedEntities to a new queue containing maxEntities unique integers.
Methods
addEntity
protected Integer addEntity();
Pops the next available entity index off the queue, and returns its value.
Returns -1 if there is no remaining unused entities.
getMaxSize
protected Integer getMaxSize();
Gets the current maximum entity count.
getRegistrations
protected BitSet getRegistrations(int entity);
Returns the BitSet of registrations the entity has.
If the call results in an IndexOutOfBoundsError, then returns a new BitSet();
registerComponent
protected void registerComponent(int component, int entity);
Sets the bit component in entityRegistrations for entity to true.
removeEntity
protected void removeEntity(int entity);
Adds the entity's index back to the unused queue, and clears the assigned registration bits
Note
This function should not be called directly. Doing so will leave component data in memory, and will cause desynchronisation of the system registrations.
resize
protected boolean resize(int newSize, SystemManager systemManager, ComponentManager componentManager);
Resizes the currentSize of the entity manager. Moves elements above newSize if space is available.
If the current defined elements won't fit, the operation returns false and the previous state is maintained.
setRegistrations
protected void setRegistrations(int entity, BitSet registrations);
Sets the entity's registrations to the provided BitSet
unregisterComponent
protected void unregisterComponent(int component, int entity);
Sets the bit component in entityRegistrations for entity to false.
Returns true if successful.
Fields
entityRegistrations
List<BitSet> entityRegistrations;
The BitSet of registrations for each entity
maxSize
private int maxSize = 1024;
The current maximum entity count.
Default 1024
unusedEntities
Queue<Integer> unusedEntities;
The queue of unused entity values