def __init__(self):
# Reference to the engine that it exists in
self.engine = None
self.systems = list()
self.entity_manager = EntityManager()
# for world behavior
self.scripts = list()
# add the fundamental systems
self.add_system(PhysicsSystem())
self.add_system(RenderSystem())
# bounds - negative values means no bounds
self.width = -1
self.height = -1
self.origin = Vector2(0, 0)
self.loading_scene = False
