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.
Here is my code:
# 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()
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?
Thanks for your help.
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