Pygame 中的透明精灵 [英] Transparent Sprites in Pygame

问题描述

我正在编写一些使用 Pygame 的 Python 代码，试图在背景上显示一个小精灵(一个球).我有那部分工作，但我试图让球精灵的背景透明，所以它不会显示为黑色方块内的球"精灵，而是显示黑色像素不是闪烁到显示表面.

I'm working on some Python code that uses Pygame, trying to display a small sprite (a ball) on top of a background. I have that part working, but I'm trying to get the background of the ball sprite to be transparent so it doesn't show up as a "ball within a black square" sprite, but instead shows up with the black pixels not being blitted to the display surface.

这是我的代码:

# For sys.exit()
import sys

# Pygame imports
import pygame
from pygame.locals import *

# Initialize all the Pygame Modules
pygame.init()

# Build a screen (640 x 480, 32-bit color)
screen = pygame.display.set_mode((640,480)) 

# Create and Convert image files
# Use JPG files for lots of color, and use conver()
# Use PNG files for transparency, and use convert_alpha()
background = pygame.image.load("bg.jpg").convert()
ball = pygame.image.load("ball.png").convert_alpha()
ball.set_colorkey(-1, RLEACCEL) # Use the upper-left pixel color as transparent

# The main loop
while True:

    # 1 - Process all input events
    for event in pygame.event.get():

        # Make sure to exit if the user clicks the X box
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    # 2 - Blit images to screen (main display window)
    screen.blit(background, (0,0))
    x,y = pygame.mouse.get_pos()
    x = x - ball.get_width()/2
    y = y - ball.get_height()/2
    screen.blit(ball, (x,y))

    # 3 - Update the main screen (redraw)
    pygame.display.update()

我肯定犯了一个明显的错误，但我无法弄清楚.调用 ball.set_colorkey(-1, RLEACCEL) 应该获取球精灵左上角的颜色(恰好是黑色)并将其用作像素颜色不要 blit".我错过了一步吗?

I must be making an obvious mistake, but I can't figure it out. Calling ball.set_colorkey(-1, RLEACCEL) should pick up the color of the upper-left corner of the ball sprite (which happens to be black) and use that as the pixel color "not to blit". Am I missing a step?

感谢您的帮助.

推荐答案

有每像素 alpha、颜色键 alpha 和每表面 alpha.您要的是色键.

There's per-pixel alpha, colorkey alpha, and per-surface alpha. You're asking for colorkey.

当您调用 convert_alpha() 它为每像素 alpha 创建一个新表面.

When you call convert_alpha() it creates a new surface for per-pixel alpha.

来自 set_colorkey

如果 Surface 格式化为使用每像素 alpha 值，则颜色键将被忽略.

The colorkey will be ignored if the Surface is formatted to use per pixel alpha values.

所以:使用 .convert() 加载图像 因为您想使用颜色键.然后调用set_colorkey.

So: Load image with .convert() Since you want to use a color key. Then call set_colorkey.

此外，我在文档中没有看到任何关于将-1"作为第一个参数传递给 set_colorkey 的内容.

Also, I saw nothing in the docs about passing "-1" as first argument to set_colorkey.

这可能来自一个教程，它有一个 load_image 函数来获取左上角像素的颜色值.

That's probably from a tutorial, which has a load_image function to grab the topleft pixel's color value.

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