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Re: [pygame] alpha (fading) with surfarray
Markus Friedl wrote:
> I have some "strange" problems when trying to do per-pixel alpha
> blending in combination with numeric... Hope anybody of you could give
> me a hint... ;)
>
> one problem is that as soon as my "fade-factor" is bigger than 0.5 I get
> an integer-overflow???
hmm, your function seems to be doing a lot of things. i'll try to
stir up a simple part of the function.
def fadealpha(image, amount):
'fade alpha by any amount, 0 to 255'
assert image.get_masks()[3] #has pixel alpha
alpha = pygame.surfarray.array_alpha(image)
fadealpha = minimum((alpha * amount) >> 8, 255)
alpha[:] = fadealpha.astype('b')
(hopefully this works, my email is less picky on syntax than python)
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