bullet.py

import pygame
from settings import BULLET_SPEED, HEIGHT

class Bullet(pygame.sprite.Sprite):
	def __init__(self, pos, size, side):
		super().__init__()
		self.x = pos[0]
		self.y = pos[1]

		# bullet info
		img_path = f'assets/bullet/{side}-bullet.png'
		self.image = pygame.image.load(img_path)
		self.image = pygame.transform.scale(self.image, (size, size))
		self.rect = self.image.get_rect(topleft = pos)
		self.mask = pygame.mask.from_surface(self.image)

		# different bullet movement direction for both player and enemy (alien)
		if side == "enemy":
			self.move_speed = BULLET_SPEED
		elif side == "player":
			self.move_speed = (- BULLET_SPEED)


	def _move_bullet(self):
		self.rect.y += self.move_speed


	def update(self):
		self._move_bullet()
		self.rect = self.image.get_rect(topleft=(self.rect.x, self.rect.y))

		# delete the bullet if it get through out of the screen
		if self.rect.bottom <= 0 or self.rect.top >= HEIGHT:
			self.kill()