在pygame中背景消失后，如何保持相同的背景颜色？

编程问答 2022-08-14

问题描述

我是一个初学者，我在做一个需要背景褪色的游戏。我编写的程序会使背景褪色，但是并不能保持其刚刚褪色的颜色，因为它会跳回到一段时间后的颜色。我希望它也可以在特定时间使其褪色，例如，我希望程序在游戏进入20,000毫秒时就褪色，而不是按MOUSEBUTTONDOWN键，这就是为什么我写了'print（pygame。 time.get_ticks（）），但我在使用它时遇到麻烦，如果还有其他方法，请对其进行评论以供我参考。谢谢！

import pygame
import time
pygame.init()

disPLAY_HEIGHT = 700
disPLAY_WIDTH = 900

screen = pygame.display.set_mode((disPLAY_WIDTH,disPLAY_HEIGHT))

clock = pygame.time.Clock()
FPS = 60

#colors
WHITE = (255,255,255)
BLACK = (0,0)
SKY_BLUE = (102,178,255)


def fade(width,height):
    fade = pygame.Surface((width,height))
    fade.fill((31,97,141))
    for alpha in range(0,300):
        fade.set_alpha(alpha)
        screen.blit(fade,(0,0))
        pygame.display.update()
        print(pygame.time.get_ticks())
        screen.fill((31,141))

running = True
while running:
    screen.fill(SKY_BLUE)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        elif event.type == pygame.MOUSEBUTTONDOWN:
            fade(disPLAY_WIDTH,disPLAY_HEIGHT)

    clock.tick(FPS)
    pygame.display.update()

解决方法

要淡化背景并保持背景，您需要创建一个可以通过淡入功能和主循环访问的共享表面。在主体上，检查计数器并运行淡入淡出过程。这将暂停主循环的淡入淡出。淡入淡出完成后，检查淡入淡出表面变量并将其变薄（如果已设置）。

这是更新的代码：

fade = None  # before fade process

def dofade(width,height):
    global fade  # share variable with main loop
    fade = pygame.Surface((DISPLAY_WIDTH,DISPLAY_HEIGHT))
    fade.fill((31,97,141))
    for alpha in range(0,300):
        fade.set_alpha(alpha)
        screen.blit(fade,(0,0))
        pygame.display.update()
        #print(pygame.time.get_ticks())
        clock.tick(FPS)
        #screen.fill((31,141))

running = True
while running:
    screen.fill(SKY_BLUE)  # initial color
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        elif event.type == pygame.MOUSEBUTTONDOWN:  # can start fade early
            dofade(DISPLAY_WIDTH,DISPLAY_HEIGHT)
            
    tks = pygame.time.get_ticks()
    if (tks >= 20000 and not fade): # if hit counter and fade not processed yet
        dofade(DISPLAY_WIDTH,DISPLAY_HEIGHT)  # loop paused for fade process
    if fade: # if fade process done
        screen.blit(fade,0)) # always show fade surface

    clock.tick(FPS)
    pygame.display.update()
,

只需将新颜色分配给变量SKY_BLUE，它将一直使用它

def fade(width,height):
    global SKY_BLUE
    
    # ... your code ...

    print('after fade')

    SKY_BLUE = (31,141)

我的版本有其他更改

import pygame

# --- constants ---

DISPLAY_HEIGHT = 700
DISPLAY_WIDTH = 900

WHITE = (255,255,255)
BLACK = (0,0)
SKY_BLUE = (102,178,255)

FPS = 60

# --- functions ---

def fade(width,height):
    global SKY_BLUE
    
    fade = pygame.Surface((width,height))
    fade.fill((31,141))

    for alpha in range(0,256):
        fade.set_alpha(alpha)

        screen.blit(fade,0))

        clock.tick(FPS)

        pygame.display.update()

    print('after fade')

    SKY_BLUE = (31,141)
    
# --- main ---

pygame.init()
screen = pygame.display.set_mode((DISPLAY_WIDTH,DISPLAY_HEIGHT))

clock = pygame.time.Clock()
    
running = True
while running:
    screen.fill(SKY_BLUE)
    
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        elif event.type == pygame.MOUSEBUTTONDOWN:
            fade(DISPLAY_WIDTH,DISPLAY_HEIGHT)

    clock.tick(FPS)
    pygame.display.update()

# - end -

pygame.quit()

您也可以使用表面。

首次使用颜色为SKY_BLUE的表面

background = pygame.Surface((DISPLAY_WIDTH,DISPLAY_HEIGHT))
background.fill(SKY_BLUE)

running = True
while running:

    screen.blit(background,0))

并在褪色后将其替换

def fade(width,height):
    global background
    
    # ... code ... 

    print('after fade')

    background = fade

顺便说一句：在这个地方，最好对表面fade和函数fade()使用不同的名称，因为这可能会误导我。

import pygame

# --- constants ---

DISPLAY_HEIGHT = 700
DISPLAY_WIDTH = 900

WHITE = (255,height):
    global background
    
    surface = pygame.Surface((width,height))
    surface.fill((31,256):
        surface.set_alpha(alpha)

        screen.blit(surface,0))

        clock.tick(FPS)

        pygame.display.update()

    print('after fade')

    background = surface
    
# --- main ---

pygame.init()
screen = pygame.display.set_mode((DISPLAY_WIDTH,DISPLAY_HEIGHT))

clock = pygame.time.Clock()
    
background = pygame.Surface((DISPLAY_WIDTH,0))
    
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        elif event.type == pygame.MOUSEBUTTONDOWN:
            fade(DISPLAY_WIDTH,DISPLAY_HEIGHT)

    clock.tick(FPS)
    pygame.display.update()

# - end -

pygame.quit()

对于2万毫秒后的衰落，您可以使用pygame.time.get_ticks()获取当前时间并计算何时开始衰落（start_fading），然后在循环中再次获取当前时间并与{{1}比较}开始褪色。

它可能需要布尔变量（start_fading）才能在第一次淡入淡出之后不再执行。

True/False

如果要重复衰落，请不要使用current_time = pygame.time.get_ticks() start_fading = current_time + 20000 faded = False running = True while running: screen.blit(background,0)) for event in pygame.event.get(): if event.type == pygame.QUIT: running = False #elif event.type == pygame.MOUSEBUTTONDOWN: # fade(DISPLAY_WIDTH,DISPLAY_HEIGHT) current_time = pygame.time.get_ticks() if not faded and current_time >= start_fading: fade(DISPLAY_WIDTH,DISPLAY_HEIGHT) faded = True clock.tick(FPS) pygame.display.update() ，而要在衰落后使用faded 

start_fading

如果希望更多的元素延迟运行，则可以将它们保留在列表中，并使用 if current_time >= start_fading: fade(DISPLAY_WIDTH,DISPLAY_HEIGHT) start_fading = current_time + 20000 循环，并在运行某些功能后将其从此列表中删除。但是我不会在这里使用它。

for

还有另一种方法-您可以将pygame.time.set_timer()与import pygame # --- constants --- DISPLAY_HEIGHT = 700 DISPLAY_WIDTH = 900 WHITE = (255,DISPLAY_HEIGHT)) background.fill(SKY_BLUE) current_time = pygame.time.get_ticks() start_fading = current_time + 20000 faded = False running = True while running: screen.blit(background,DISPLAY_HEIGHT) faded = True clock.tick(FPS) pygame.display.update() # - end - pygame.quit() 结合使用，以生成自定义事件，并且会有所延迟

pygame.USEREVENT

然后您可以使用FADE_EVENT = pygame.USEREVENT pygame.time.set_timer(FADE_EVENT,2000) 来捕获它并执行for event in pygame.event.get(): 

fade()
        if event.type == FADE_EVENT:
            pygame.time.set_timer(FADE_EVENT,0) # turn off after one use 
            fade(DISPLAY_WIDTH,DISPLAY_HEIGHT)
backgroundfadepygamepythonpython-3.x