ship.py

import pygame
from pygame.sprite import Sprite

class Ship(Sprite):
	"""A class to manage the ship."""

	def __init__(self, ai_game):
		"""Initialize the ship and set its starting position."""
		super().__init__()
		self.screen = ai_game.screen
		self.settings = ai_game.settings
		self.screen_rect = ai_game.screen.get_rect()

		# Load the ship image and get its rect.
		self.image = pygame.image.load('images/ship4.bmp')
		self.rect = self.image.get_rect()

		# Start each new ship at the bottom center of the screen."""
		self.rect.midbottom = self.screen_rect.midbottom

		# Store a decimal value for the ship's horizontal position.
		self.x = float(self.rect.x)
		self.y = float(self.rect.y)

		# Movement flag
		self.moving_right = False
		self.moving_left = False
		self.moving_up = False
		self.moving_down = False
	def update(self):
		"""Update the ship's position based on the movement flag."""
		# Update the ship's x value, not the rect.
		if self.moving_right and self.rect.right < self.screen_rect.right:
			self.x += self.settings.ship_speed
		if self.moving_left and self.rect.left > 0:
			self.x -= self.settings.ship_speed
		if self.moving_up and self.y > 0 :
			self.y -= self.settings.ship_speed
		if self.moving_down and self.y < self.settings.screen_height - 85:
			self.y += self.settings.ship_speed

		# Update rect object from self.x.
		self.rect.x = self.x
		self.rect.y = self.y

	def blitme(self):
		"""Draw the ship at its current location."""
		self.screen.blit(self.image, self.rect)

	def center_ship(self):
		"""Center the ship on the screen."""
		self.rect.midbottom = self.screen_rect.midbottom
		self.x = float(self.rect.x)