我正在学习Python和Pygame，我的第一个项目是一个简单的贪吃蛇游戏。我试图让贪吃蛇每0.25秒移动一次。下面是我的代码循环部分：
while True:
check_for_quit()
clear_screen()
draw_snake()
draw_food()
check_for_direction_change()
move_snake() #How do I make it so that this loop runs at normal speed, but move_snake() only executes once every 0.25 seconds?
pygame.display.update()
Clock并计算滴答数。pygame.time.set_timer()函数：
pygame.time.set_timer()
重复在事件队列上创建一个事件
set_timer(eventid, milliseconds) -> None
设置一个事件类型，使其每隔一定的毫秒数出现在事件队列中。直到经过了指定的时间量，第一个事件才会出现。
每个事件类型都可以附加一个单独的计时器。最好使用介于pygame.USEREVENT和pygame.NUMEVENTS之间的值。
要禁用事件的计时器，请将milliseconds参数设置为0。
下面是一个小的运行示例，蛇每250毫秒移动一次：
import pygame
pygame.init()
screen = pygame.display.set_mode((300, 300))
player, dir, size = pygame.Rect(100,100,20,20), (0, 0), 20
MOVEEVENT, t, trail = pygame.USEREVENT+1, 250, []
pygame.time.set_timer(MOVEEVENT, t)
while True:
keys = pygame.key.get_pressed()
if keys[pygame.K_w]: dir = 0, -1
if keys[pygame.K_a]: dir = -1, 0
if keys[pygame.K_s]: dir = 0, 1
if keys[pygame.K_d]: dir = 1, 0
if pygame.event.get(pygame.QUIT): break
for e in pygame.event.get():
if e.type == MOVEEVENT: # is called every 't' milliseconds
trail.append(player.inflate((-10, -10)))
trail = trail[-5:]
player.move_ip(*[v*size for v in dir])
screen.fill((0,120,0))
for t in trail:
pygame.draw.rect(screen, (255,0,0), t)
pygame.draw.rect(screen, (255,0,0), player)
pygame.display.flip()
pygame.time.set_timer非常容易安排事务，因为现在可以触发自定义事件一次。import pygame
pygame.init()
screen = pygame.display.set_mode((640, 480))
ACTION = pygame.event.custom_type() # our custom event that contains an action
clock = pygame.time.Clock()
def main():
shield = 0
# function to activate the shield
# note that shield is NOT just a boolean flag,
# but an integer. Everytime we activate the shield,
# we increment it by 1. If we want to deactivate the
# shield later, we can test if the deactivate event
# is the latest one. If not, then nothing should happen.
def activate_shield():
nonlocal shield
shield += 1
return shield
# function that creates the function that is triggered
# after some time. It's nested so we can pass and capture
# the id variable to check if the event is actually the
# last deactivate event. If so, we reset shield to 0.
def remove_shield(id):
def action():
nonlocal shield
if shield == id:
shield = 0
return action
while True:
for e in pygame.event.get():
if e.type == pygame.QUIT: return
if e.type == pygame.KEYDOWN:
# activate the shield
id = activate_shield()
# deactivate it 2000ms in the future
# pygame will post this event into the event queue at the right time
pygame.time.set_timer(pygame.event.Event(ACTION, action=remove_shield(id)), 2000, 1)
if e.type == ACTION:
# if there's an ACTION event, invoke its action!!!
e.action()
screen.fill('black')
# is the shield active?
if shield:
pygame.draw.circle(screen, 'red', (320, 220), 35, 4)
# our green little guy
pygame.draw.rect(screen, 'green', (300, 200, 40, 40))
pygame.display.flip()
clock.tick(60)
main()
repl.it@queueseven/Simple-Scheduler
MOVE_EAST = (1, 0) 等，然后创建命令列表，例如 command_list = [MOVE_EAST, MOVE_NORTH, ....]，在事件处理程序中执行 dir = command_list.pop(0) 来获取下一个命令，然后再执行 player.move_ip... 行。 - slothClock类的方法tick将向您报告自上次调用tick以来的毫秒数。因此，您可以在游戏循环的每个迭代的开头（或结尾）调用tick一次，并将其返回值存储在名为dt的变量中。然后使用dt来更新与时间有关的游戏状态变量。time_elapsed_since_last_action = 0
clock = pygame.time.Clock()
while True: # game loop
# the following method returns the time since its last call in milliseconds
# it is good practice to store it in a variable called 'dt'
dt = clock.tick()
time_elapsed_since_last_action += dt
# dt is measured in milliseconds, therefore 250 ms = 0.25 seconds
if time_elapsed_since_last_action > 250:
snake.action() # move the snake here
time_elapsed_since_last_action = 0 # reset it to 0 so you can count again
如果你想在Pygame中控制时间，有两个选项：
使用pygame.time.get_ticks()来测量时间，并根据时间来控制对象的逻辑。
使用定时器事件。使用pygame.time.set_timer()重复创建一个USEREVENT放入事件队列中。当事件发生时改变对象状态。
以下问题的答案示例展示了如何使用这些方法：
import pygame
pygame.init()
window = pygame.display.set_mode((400, 200))
clock = pygame.time.Clock()
rect = pygame.Rect(0, 80, 20, 20)
time_interval = 500 # 500 milliseconds == 0.1 seconds
next_step_time = 0
run = True
while run:
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
current_time = pygame.time.get_ticks()
if current_time > next_step_time:
next_step_time += time_interval
rect.x = (rect.x + 20) % window.get_width()
window.fill(0)
pygame.draw.rect(window, (255, 0, 0), rect)
pygame.display.flip()
clock.tick(100)
pygame.quit()
exit()
import pygame
pygame.init()
window = pygame.display.set_mode((400, 200))
clock = pygame.time.Clock()
rect = pygame.Rect(0, 80, 20, 20)
time_interval = 500 # 500 milliseconds == 0.1 seconds
timer_event = pygame.USEREVENT+1
pygame.time.set_timer(timer_event, time_interval)
run = True
while run:
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
if event.type == timer_event:
rect.x = (rect.x + 20) % window.get_width()
window.fill(0)
pygame.draw.rect(window, (255, 0, 0), rect)
pygame.display.flip()
clock.tick(100)
pygame.quit()
exit()
