scripts

src/alien.py

@@ -0,0 +1,22 @@
+import pygame
+from pygame.sprite import Sprite
+from os.path import dirname, abspath, join
+path = dirname(dirname(abspath(__file__)))
+
+class Alien(Sprite):
+	"""A single alien"""
+
+	def __init__(self, ai_game):
+
+		super().__init__()
+		self.screen = ai_game.screen
+
+		self.image = pygame.image.load(join(path, "img", "alien.bmp"))
+		self.rect = self.image.get_rect()
+
+		#Start position
+		self.rect.x = self.rect.width
+		self.rect.y = self.rect.height
+
+		#Decimal value for horizontal position
+		self.x = float(self.rect.x)

src/alieninvasion.py

@@ -2,6 +2,8 @@
 import pygame
 from settings import Settings
 from ship import Ship
+from bullet import Bullet
+from alien import Alien
 
 
 class AlienInvasion:
@@ -19,14 +21,46 @@ def __init__(self):
 
 		self.bg_color = (230, 230, 230)
 		pygame.display.set_caption("Alien Invasion")
+
 		self.ship = Ship(self)
+		self.bullets = pygame.sprite.Group()
+		self.aliens = pygame.sprite.Group()
+
+		self._create_fleet()
+
+
+	def _create_fleet(self):
+
+		alien = Alien(self)
+		alien_width, alien_height = alien.rect.size
+		available_space_x = self.settings.screen_width - (2*alien_width)
+		n_aliens_x = available_space_x // (2*alien_width)
+
+		ship_height = self.ship.rect.height
+		available_space_y = self.settings.screen_height - 3*alien_height - ship_height
+		n_rows = available_space_y // (2*alien_height)
+
+		for row in range(n_rows):
+			for col in range(n_aliens_x):
+				self._create_alien(col, row)
+
+
+	def _create_alien(self, col, row):
+
+		alien = Alien(self)
+		alien_width, alien_height = alien.rect.size
+		alien.x = alien_width + 2*alien_width*col
+		alien.rect.x = alien.x
+		alien.rect.y = alien_height + 2*alien_height*row
+		self.aliens.add(alien)
 
 
 	def run_game(self):
 
 		while True:
 			self._check_events()
 			self.ship.update()
+			self._update_bullets()
 			self._update_screen()
 
 
@@ -42,24 +76,51 @@ def _check_events(self):
 
 
 	def _check_keydown_events(self, event):
+
 		if event.key == pygame.K_RIGHT:
 			self.ship.moving_right = True
 		elif event.key == pygame.K_LEFT:
 			self.ship.moving_left = True
 		elif event.key == pygame.K_q:
 			sys.exit()
+		elif event.key == pygame.K_SPACE:
+			self._fire_bullet()
 
 
 	def _check_keyup_events(self, event):
+
 		if event.key == pygame.K_RIGHT:
 			self.ship.moving_right = False
 		elif event.key == pygame.K_LEFT:
 			self.ship.moving_left = False
 
 
+	def _fire_bullet(self):
+
+		if len(self.bullets) < self.settings.bullet_limit:
+			new_bullet = Bullet(self)
+			self.bullets.add(new_bullet) #add bullet to to bullets group
+
+
+	def _update_bullets(self):
+
+		self.bullets.update()
+
+		#Delete bullets off screen
+		for bullet in self.bullets.copy():
+			if bullet.rect.bottom <= 0:
+				self.bullets.remove(bullet)
+
+
 	def _update_screen(self):
+
 		self.screen.fill(self.settings.bg_color)
 		self.ship.blitme()
+		for bullet in self.bullets.sprites():
+			bullet.draw_bullet()
+		#Draw each alien in the group
+		self.aliens.draw(self.screen)
+
 		pygame.display.flip()
 
 

src/bullet.py

@@ -13,7 +13,18 @@ def __init__(self, ai_game):
 		self.color = self.settings.bullet_color
 
 		self.rect = pygame.Rect(0, 0,
-			self.settings.bullet_width, self.settings.bullet_height)
+			self.settings.bullet_width,
+			self.settings.bullet_height)
 		self.rect.midtop = ai_game.ship.rect.midtop
 
-		self.y = float(self.rect.y)
+		self.y = float(self.rect.y)
+
+
+	def update(self):
+		"""Move bullet up"""
+		self.y -= self.settings.bullet_speed
+		self.rect.y = self.y
+
+
+	def draw_bullet(self):
+		pygame.draw.rect(self.screen, self.color, self.rect)

src/settings.py

@@ -11,5 +11,6 @@ def __init__(self):
 		#Bullets
 		self.bullet_speed = 1.
 		self.bullet_width = 3
-		self.bullet_height = 15
-		self.bullet_color = (60, 60, 60)
+		self.bullet_height = 12
+		self.bullet_color = (60, 60, 60)
+		self.bullet_limit = 3

src/ship.py

@@ -1,6 +1,5 @@
 import pygame
 from os.path import dirname, abspath, join
-
 #Parent directory
 path = dirname(dirname(abspath(__file__)))
 
@@ -36,5 +35,5 @@ def update(self):
 
 
 	def blitme(self):
-		"""Draw ship at new loaction"""
+		"""Draw ship at new location"""
 		self.screen.blit(self.image, self.rect)