#makes a background that moves and stuff
class BackgroundManager(pygame.sprite.Sprite):
	stars=[ ]
	last_stars=[ ]
	
	def __init__(self):
		for x in range(init_stars):
			self.add_star()
	
	def update(self):
		self.last_stars = [st for st in self.stars if st.top <= WIN_RESY]
		
		for counter,star in enumerate(self.stars):
			if star.top > WIN_RESY:
				del self.stars[counter]
				del self.last_stars[counter]
				self.add_star()
			else:
				star.move_ip(0,star.get_speed())
		
	
	def draw(self):
		for star in self.stars:
			surface.fill((255,255,255),star)
		return self.stars
		
	def clear(self):
		for star in self.last_stars:
			surface.fill((0,0,0),star)
			
	def add_star(self):
		size=random.randint(3,6)
		x=random.randint(0,WIN_RESX)
		rect=star(x,0,size,size)
		rect.set_speed(random.randint(8,BG_Speed))
		self.stars.append(rect)
		self.last_stars.append(rect)
		
##########################
class star(pygame.Rect):
	def set_speed(self,tspeed):
		self.speed=tspeed
	def get_speed(self):
		return self.speed