ship.py

import pygame

class Ship():
	def __init__(self, ai_settings, screen):
		"""Initialize the ship and set its starting position."""
		self.screen = screen
		self.ai_settings = ai_settings
	
		# Load the ship image and get its rect.
		self.image = pygame.image.load('images/ship.bmp')
		self.rect = self.image.get_rect()
		self.screen_rect = screen.get_rect()
	
		# Start each new ship at the bottom center of the screen.
		self.rect.centerx = self.screen_rect.centerx
		self.rect.bottom = self.screen_rect.bottom
		
		# Store a decimal value for the ship's center.
		self.centerx = float(self.rect.centerx)
		self.centery = float(self.rect.centery)
		
		# 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 center value, not the rect.
		if self.moving_right and self.rect.right < self.screen_rect.right:
			self.centerx += self.ai_settings.ship_speed_factor
		if self.moving_left and self.rect.left > 0:
			self.centerx -= self.ai_settings.ship_speed_factor
			
		'''if self.moving_up and self.rect.top > 0:
			self.centery -= self.ai_settings.ship_speed_factor
		if self.moving_down and self.rect.bottom < self.screen_rect.bottom:
			self.centery += self.ai_settings.ship_speed_factor'''
			
		# Update rect object from self.center
		self.rect.centerx = self.centerx
		self.rect.centery = self.centery
	
	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.centerx = self.screen_rect.centerx