class World:
def __init__(self):
self._em = EventManager()
self._entities = []
self._systems = {} # Maps system type to system itself.
self._time = 0
def addEntity(self, entity, delayEvent = False):
"""Adds a new entity to the world. Unless explicitly asked to do so through
delayEvent, an event is generated. It is useful to delay event signalling
if some preprocessing on the entity is required."""
self._entities.append(entity)
for _, system in self._systems.items():
if system.applicable(entity):
system.addEntity(entity)
if not delayEvent:
self.throwEntityCreatedEvent(entity)
def entityUpdatedComponents(self, entity, oldComponentTypeList):
"""The method takes the old components of the entity, and the entity with
components removed/added. It will update systems."""
for _, system in self._systems.items():
if (system.applicable(entity) and
not system.applicableComponents(oldComponentTypeList)):
system.addEntity(entity)
elif (not system.applicable(entity) and
system.applicableComponents(oldComponentTypeList)):
system.removeEntity(entity)
def throwEntityCreatedEvent(self, entity):
"""Signals that entity has been created."""
event = Event(self._time, Event.ENTITY_ADDED)
event.entity = entity
self._em.handleEvent(event)
def removeEntity(self, entity):
self._entities.remove(entity)
for _, system in self._systems.items():
if system.applicable(entity):
system.removeEntity(entity)
event = Event(self._time, Event.ENTITY_REMOVED)
event.entity = entity
entity._em.handleEvent(event)
self._em.handleEvent(event)
def addSystem(self, system):
self._systems[type(system)] = system
def removeSystem(self, system):
del self._systems[type(system)]
def tick(self, dt):
self._time = self._time + dt
for system in self._systems.values():
system.tick(dt)
def __init__(self):
self._em = EventManager()
self._entities = []
self._systems = {} # Maps system type to system itself.
self._time = 0
