如何使对象在 pygame 中褪色 [英] How to make an object fades color in pygame

问题描述

我想要一个矩形作为生命条从绿色渐变为红色，但在互联网上找不到简单的方法.

I want a rectangle to fade from green to red for a life-bar, but couldn't find easy way to do it on internet.

我是这样试的(只是为了从红色变成黄色):

I tried like this (just for going from red to yellow):

colorR = 0
colorG = 255
colorB = 0
change = True
while change:
     pygame.draw.rect(win, (colorR, colorG, colorB), (10, 10, 200, 50), 0)
     colorR += 1
     if colorR == 255:
          print("done")

我也尝试使用 for i in range(0, 255):

它说 pygame.draw.rect(win, (colorR, colorG, colorB), (10, 10, 200, 50), 0)类型错误:无效的颜色参数

但是当我像这样绘制矩形时:

But when I just draw the rectangle like this :

colorR = 0
colorG = 255
colorB = 0
pygame.draw.rect(win, (colorR, colorG, colorB), (10, 10, 200, 50), 0)

矩形显示为绿色.

我的方法是否正确，或者我有.以完全不同的方式做到这一点?谢谢解答

Is my method correct, or do I have. to do it in a complete other way ? Thanks for the answer

这是整个程序，其中可能存在错误，因为矩形在获得最终颜色之前没有出现

edit : here's the whole program, there are maybe mistakes in there because the rectangle doesn't appear before it gets its final color

import pygame, math
pygame.init()
length = 1440
heigth  = 700
win = pygame.display.set_mode((length, heigth))#, pygame.FULLSCREEN)
menuImg = pygame.image.load('menu_img.jpg')
laser = pygame.image.load('projectile.png')
clock = pygame.time.Clock()
game = False
def rgw():  
    win.fill((0, 0, 255))
    if game:
        print("game")
        colorR = 0
        colorG = 255
        colorB = 0
        change = True
        while change:
            pygame.draw.rect(win, (colorR, colorG, colorB), (10, 10, 200, 50), 0)
            colorR += 1
            if colorR == 255:
                change = False
        pygame.display.flip()
    pygame.display.update()
run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        if event.type == pygame.MOUSEBUTTONDOWN:
            game = True

        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_BACKSPACE:
                run = False

    rgw()
pygame.quit()

推荐答案

要更改显示表面可见，您必须调用 pygame.display.flip() 或 pygame.display.update().此外，我建议通过 pygame.event.get() 或 pygame.event.pump() 处理事件.
请注意，您必须在循环中进行延迟，否则颜色会迅速褪色.如果颜色不在 [0, 255] 范围内，您将收到无效颜色参数"错误.发生这种情况是因为您示例中的循环永远不会终止.你错过了change = False.

To make changes to the display surface visible you have to call pygame.display.flip() or pygame.display.update(). Furthermore I recommend to handle the events by either pygame.event.get() or pygame.event.pump().
Note you have to do a delay in the loop, otherwise the color will fade rapidly. If the color is not in range [0, 255] you'll get "invalid color argument" error. That happens because the loop in your example never terminates. You missed change = False.

无论如何，由于您有一个应用程序循环，因此无需在单独的循环中执行淡入淡出.使用主应用程序循环:

anyway, since you have a application loop, there is no need to do the fade in a separate loop. Use the main application loop:

game = True
colorR = 0
colorG = 255
colorB = 0
def rgw(): 
    global colorR, colorG, colorB
    win.fill((0, 0, 255))
    if game:
        pygame.draw.rect(win, (colorR, colorG, colorB), (10, 10, 200, 50), 0)
        if colorR < 255:
            colorR += 1
    pygame.display.update()

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        if event.type == pygame.MOUSEBUTTONDOWN:
            game = True
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_BACKSPACE:
                run = False

    rgw()

pygame.quit()

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