You could use counter to count loops in main loop since last shot - if it is bigger than (for example) 10 than you clear counter and shoot - in more complicated game you could use pygame.time.get_ticks() to count time in milliseconds since last shot
Another method is to fire shot only if you have less than 2 shot on screen.
EDIT:
Your code would look like this - simple example. Use keys: LEFT, RIGHT, SPACE, P (for pause).
There is still much to do. For example better collision detect - pygame.sprite.collide_rect()
(I attached my bitmaps at the end)
#-----!!!!SPACE INVADERS!!!!-----
import pygame
from pygame.locals import *
#----------------------------------------------------------------------
class Ship():
def __init__(self, screen_rect):
#self.image = pygame.image.load("spaceship.png")
self.image = pygame.image.load("ball1.png")
self.image = pygame.transform.scale(self.image, (100,50))
self.rect = self.image.get_rect()
# put ship bottom, center x
self.rect.bottom = screen_rect.bottom
self.rect.centerx = screen_rect.centerx
self.move_x = 0
self.shots = []
self.shots_count = 0
self.max_shots = 2
#--------------------
def event_handler(self, event):
#print "debug: Ship.event_handler"
if event.type == KEYDOWN:
if event.key == K_LEFT:
self.move_x = -5
elif event.key == K_RIGHT:
self.move_x = 5
elif event.key == K_SPACE:
if len(self.shots) < self.max_shots:
self.shots.append(Bullet(self.rect.centerx, self.rect.top))
if event.type == KEYUP:
if event.key in (K_LEFT, K_RIGHT):
self.move_x = 0
def update(self):
#print "debug: Ship.update: move_x", self.move_x
self.rect.x += self.move_x
for s in self.shots:
s.update()
for i in range(len(self.shots)-1, -1, -1):
print "debug: Ship.update: testing bullet ", i
if not self.shots[i].is_alive:
print "debug: Ship.update: removing bullet ", i
del self.shots[i]
#--------------------
def draw(self, screen):
#print "debug: Ship.draw"
screen.blit(self.image, self.rect.topleft)
for s in self.shots:
s.draw(screen)
def bullet_detect_collison(self, enemy_list):
for s in self.shots:
for e in enemy_list:
if pygame.sprite.collide_circle(s, e):
s.is_alive = False
e.is_alive = False
#----------------------------------------------------------------------
class Bullet():
def __init__(self, x, y):
#self.image = pygame.image.load("SingleBullet.png")
self.image = pygame.image.load("ball2.png")
self.image = pygame.transform.scale(self.image, (25,25))
self.rect = self.image.get_rect()
self.rect.centerx = x
self.rect.centery = y
self.is_alive = True
#--------------------
def update(self):
self.rect.y -= 15
if self.rect.y < 0:
self.is_alive = False
#--------------------
def draw(self, screen):
screen.blit(self.image, self.rect.topleft)
#----------------------------------------------------------------------
class Enemy():
def __init__(self, x, y):
self.image = pygame.image.load("ball3.png")
self.rect = self.image.get_rect()
self.rect.centerx = x
self.rect.centery = y
self.is_alive = True
#--------------------
def update(self):
self.rect.y += 1
#~ if self.rect.y < 0:
#~ self.is_alive = False
#--------------------
def draw(self, screen):
screen.blit(self.image, self.rect.topleft)
#----------------------------------------------------------------------
class Game():
def __init__(self):
pygame.init()
w, h = 800, 800
self.screen = pygame.display.set_mode((w,h))
pygame.mouse.set_visible(False)
self.ship = Ship(self.screen.get_rect())
self.enemies = []
for i in range(100, 800, 100):
self.enemies.append(Enemy(i, 100))
font = pygame.font.SysFont("", 72)
self.text_paused = font.render("PAUSED", True, (255, 0, 0))
self.text_paused_rect = self.text_paused.get_rect(center=self.screen.get_rect().center)
#-----MAIN GAME LOOP-----
def run(self):
clock = pygame.time.Clock()
RUNNING = True
PAUSED = False
while RUNNING:
clock.tick(30)
#--- events ---
for event in pygame.event.get():
if event.type == pygame.QUIT:
RUNNING = False
if event.type == KEYDOWN:
if event.key == K_ESCAPE:
RUNNING = False
if event.key == K_p:
PAUSED = not PAUSED
if not PAUSED:
self.ship.event_handler(event)
#--- changes ---
if not PAUSED:
self.ship.update()
for e in self.enemies:
e.update()
self.ship.bullet_detect_collison(self.enemies)
for i in range(len(self.enemies)-1, -1, -1):
print "debug: Ship.update: testing bullet ", i
if not self.enemies[i].is_alive:
print "debug: Ship.update: removing bullet ", i
del self.enemies[i]
#--- draws ---
self.screen.fill((0,0,0))
self.ship.draw(self.screen)
for e in self.enemies:
e.draw(self.screen)
if PAUSED:
self.screen.blit(self.text_paused, self.text_paused_rect)
pygame.display.update()
#--- quit ---
pygame.quit()
#---------------------------------------------------------------------
Game().run()
ball1.png
ball2.png
ball3.png
Screenshot
