我希望我的立方体在pygame中每一帧每秒都能重复向前移动，但我不知道哪里出了问题？

Question

我认为这与移动是一个事件的事实有关，而我的函数“动量”并不在那里，这就是我试图让它反复移动的方式。我想知道我做错了什么，以及将来如何思考这样的代码。我刚刚开始学习pygame，这实际上是我使用它的第一个项目。我也已经写了一年的代码(上个月)，我真的很喜欢编程。

import pygame
pygame.init()
running = True
x = 0
y = 0
momentum = "null"
def draw_rect(x, y, size, size1):
    pygame.draw.rect(screen, (204, 65, 242), (x, y, size, size1))
def momentum_forward(x, y):
    if momentum == "a":
        x += -25
    if momentum == "d":
        x += 25
    if momentum == "w":
        y += -25
    if momentum == "s":
        y += 25
while running:
    FPS = 8
    fpsClock = pygame.time.Clock()
    screen = pygame.display.set_mode((600, 480), 0, 32)
    draw_rect(x, y, 25, 25)
    momentum_forward(x, y)
    print(momentum)
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_a:
                x += -25
                momentum = "a"
            if event.key == pygame.K_d:
                x += 25
                momentum = "d"
            if event.key == pygame.K_w:
                y += -25
                momentum = "w"
            if event.key == pygame.K_s:
                y += 25
                momentum = "s"
        if event.type == pygame.QUIT:
            running = False
    pygame.display.update()
    fpsClock.tick(FPS)

Answer 1

您将x和y传递给momentum_forward函数，因此函数中的更新不会更新全局的x和y值。

尝试以下代码：

import pygame
pygame.init()
running = True
x = 0
y = 0
momentum = None  # null in python
def draw_rect(x, y, size, size1):
    pygame.draw.rect(screen, (204, 65, 242), (x, y, size, size1))
    
def momentum_forward():
    global x,y    # use global variables
    if momentum == "a":
        x += -25
    if momentum == "d":
        x += 25
    if momentum == "w":
        y += -25
    if momentum == "s":
        y += 25
        
screen = pygame.display.set_mode((600, 480), 0, 32)  # only need this once
fpsClock = pygame.time.Clock()

while running:
    FPS = 8
    momentum_forward()  # don't pass x,y
#    print(momentum)
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_a:
                x += -25
                momentum = "a"
            if event.key == pygame.K_d:
                x += 25
                momentum = "d"
            if event.key == pygame.K_w:
                y += -25
                momentum = "w"
            if event.key == pygame.K_s:
                y += 25
                momentum = "s"
        if event.type == pygame.QUIT:
            running = False
            
    draw_rect(x, y, 25, 25)
    pygame.display.update()
    fpsClock.tick(FPS)