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Question

我希望代码是这样的，如果我按下某个键，手电筒颜色

pygame.draw.ellipse(gameDisplay, yellow,[375+lead_x,-43+lead_y,105,led])

变亮，如光yellow.Please assist.Here是完整代码

import pygame
pygame.init()
white = (34,34,34)
black=(0,0,0)
red=(255,0,0)
led=45
silver=(110,108,108)
yellow=(193,206,104)
yellow2=(213,230,100)
gameDisplay = pygame.display.set_mode((800,600))
pygame.display.set_caption('Slither')

gameExit=False

myfont = pygame.font.SysFont("monospace", 15)
lead_x = 300
lead_y = 300
background_color=black
while not gameExit:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            gameExit = True
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                lead_x -= 10
                print("LEFT")

            if event.key == pygame.K_RIGHT:
                lead_x +=10
                print("RIGHT")
            if event.key == pygame.K_UP:
                 lead_y -=10
                 print("UP")
            if event.key == pygame.K_DOWN:
                 lead_y +=10
                 print("DOWN")
            if event.key == pygame.K_a:
                gameDisplay.fill(red)
                led +=10
            if led == 95:
                background_color=red
                print("YOU FOUND ME.NOW YOU WILL D I E")
                background_color=red

    gameDisplay.fill(background_color)
    pygame.draw.ellipse(gameDisplay, black,[-295+300,-54+300,75,100])
    pygame.draw.ellipse(gameDisplay, red,[-285+300,-35+300,20,34])
    pygame.draw.ellipse(gameDisplay, red,[-255+300,-35+300,20,34])
    pygame.draw.rect(gameDisplay, silver,[470+lead_x,-35+lead_y,75,30])
    pygame.draw.ellipse(gameDisplay, yellow,[375+lead_x,-43+lead_y,105,led])


    pygame.display.update()

pygame.quit()
quit()

Answer 1

问题是PyGame支持RGBA color values (red, green, blue and alpha value of a Color), but unfortunately PyGames draw functions don´t draw transparently (according to the domcumanetaion).

要避免此问题，您可以

创建新表面
使用 .set_alpha()

更改其 alpha 值

将 "flashlight" 椭圆 绘制到新表面
通过调用支持 alpha 透明度的 .blit() 方法将此表面 Blit 到主屏幕 表面

这是更新后的程序：

# ... your code

alpha = 0

while not gameExit:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            gameExit = True

        if event.type == pygame.KEYDOWN:
            #...  your original code 

            if event.key == pygame.K_SPACE:
               #change alpha value
               alpha += 10

    gameDisplay.fill(background_color)

    pygame.draw.ellipse(gameDisplay, black,[-295+300,-54+300,75,100])
    pygame.draw.ellipse(gameDisplay, red,[-285+300,-35+300,20,34])
    pygame.draw.ellipse(gameDisplay, red,[-255+300,-35+300,20,34])


    alphaSurface = pygame.Surface((105,led)) # 1.

    alphaSurface.set_alpha(alpha) # 2.
    alphaSurface.fill(background_color)

    pygame.draw.ellipse(alphaSurface, yellow,[0,0,105,led]) # 3.
    gameDisplay.blit(alphaSurface, (375+lead_x,-43+lead_y)) # 4.


    pygame.draw.rect(gameDisplay, silver,[470+lead_x,-35+lead_y,75,30])

    pygame.display.update()

pygame.quit()
quit()

请注意，我们需要更改 alphaSurface 表面的背景颜色和大小 主循环的每次迭代 以获得预期结果，这可能放慢我们的游戏速度。

您还可以考虑使用 pygame.HWSURFACE 标志来 创建硬件加速表面 。有关详细信息，请参阅 PyGame documentation about surfaces。

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