[pygame] set_alpha() weirdness.

[David Clark <silenus@telus.net>]

surface.set_alpha() isn't working the way I expected. I'm not sure if
this is a pygame problem or a more general SDL one, or if my
expectations are simply all screwed up.

I'm changing a surface's alpha value over time. If I go
set_alpha(254), I can later go set_alpha(128) and it works. However,
if I ever go set_alpha(255), further calls to set_alpha() don't have
any effect, _even though_ get_alpha() still retrieves the correct
value. Weird.

Example:

surface.set_alpha(254)      # surface is fully opaque
surface.get_alpha()         # 254
surface.set_alpha(128)      # surface is 50% transparent
surface.get_alpha()         # 128
surface.set_alpha(255)      # surface is fully opaque
surface.get_alpha()         # 255
surface.set_alpha(128)      # surface is fully opaque!!! Should be 50%
surface.get_alpha()         # 128 reports right value, even though the
		            # surface is still opaque

David Clark
silenus@telus.net


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