def __init__(self, event_manager, world, area_id):
SingleListener.__init__(self, event_manager)
self.area_id = area_id
self.world = world
# Only keep weak references to the entities because they are owned by
# the World itself, not by the area. They can move between areas, or
# even be in no area at all.
self.entities = weakref.WeakValueDictionary()
# The tile map is a data structure that describes the fixed features of
# the landscape. By fix, I mean that these features cannot move.
# However, one can imagine that some of these features appear,
# disappear or change. For example, a door can open.
self.tile_map = tile.TileMap()
# The entity map is here ONLY for performance purposes. It allows a
# relatively quick access to the entities in a region. This helps us
# limiting the number of entities to look for during collisions, or
# when a creature is looking around for nearby victims.
self.entity_map = EntityMap()
# Useful for collision detection: entities are colliding if the
# distance between them is smaller than the sum of their radii. Keeping
# track of the biggest possible radius helps you delimiting the area
# containing the entities you may be colliding with. Nothing beyond
# your_radius + biggest_radius can touch you.
self._biggest_entity_radius = 0
LOGGER.debug("Area %i created.", area_id)
