Pygame显示器在If条件下不工作

Question

我试图让我的代码在屏幕中间显示一个文本，一旦一个正方形向右经过500像素，但它似乎显示我的If条件。我不知道我做错了什么

import pygame
pygame.init()
displaywidth=500
displayheight=500

gameDisplay = pygame.display.set_mode((displaywidth, displayheight))
pygame.display.set_caption("First Game")

red = (0,255,0)

font=pygame.font.Font(None, 20)

#Class
def Message(msg, color):
    screen_text=font.render(msg,True,color)
    gameDisplay.blit(screen_text,[displaywidth/2,displayheight/2])

win = pygame.display.set_mode((displaywidth, displayheight))
x = 50
y = 50
width = 40
height = 40
vel = 5

x1 = 0
y1 = 0
width1 = 40
height1 = 40
vel2 = 100
vel3=100

x2 = 100
y2 = 100
pygame.draw.rect(win, (0, 255, 0), (x, y, width, height))
run = True
while run:
    pygame.time.delay(100)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
        x -= vel2
    elif keys[pygame.K_RIGHT]:
        x += vel2
    elif keys[pygame.K_UP]:
        y1-=vel3
    elif keys[pygame.K_DOWN]:
        y1+=vel3
    if x > 500:
        Message("meow", red)
        pygame.display.update()
        print("pew")
    elif x < 0:
        x = 50
    elif y1 > 500:
        y1 = 450
    elif y1 < 0:
        y1 = 50

    print(x)
    print(y)
    win.fill((0, 0, 0))
    meow = pygame.draw.rect(win, (0, 255, 0), (x, y1, width, height))
    pygame.draw.rect(win, (160, 0, 0), (x1, y1, width1, height1))
    pygame.display.update()

pygame.quit()

我的打印命令似乎是工作，但我不知道为什么它不显示

Answer 1

问题是您的代码中有2个对pygame.display.update()的调用，但在第一个调用之后显示立即被清除：

if x > 500:
   Message("meow", red)
   pygame.display.update()  # <  
   print("pew")
# [...]

win.fill((0, 0, 0))         # <  

在绘制任何内容之前清除显示，并在主应用程序循环的末尾执行单个pygame.display.update()：

run = True
while run:
    pygame.time.delay(100)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
        x -= vel2
    elif keys[pygame.K_RIGHT]:
        x += vel2
    elif keys[pygame.K_UP]:
        y1-=vel3
    elif keys[pygame.K_DOWN]:
        y1+=vel3

    if x < 0:
        x = 50
    elif y1 > 500:
        y1 = 450
    elif y1 < 0:
        y1 = 50

    # clear dispaly
    win.fill((0, 0, 0)) 

    # draw scene
    if x > 500:
        Message("meow", red)
        print("pew")
    meow = pygame.draw.rect(win, (0, 255, 0), (x, y1, width, height))
    pygame.draw.rect(win, (160, 0, 0), (x1, y1, width1, height1))

    # update display
    pygame.display.update()