2015-03-22 12:43 GMT+01:00 Nicolai Hess <[email protected]>: > > > 2015-03-21 15:51 GMT+01:00 Eliot Miranda <[email protected]>: > >> Why not take the average of alpha in all cases? >> >> Eliot (phone) >> >> On Mar 21, 2015, at 6:32 AM, Aliaksei Syrel <[email protected]> wrote: >> > > > Or weight the argument by its alpha and don't change the alpha of the > receiver: > Color white - (Color white alpha:0) = Color white > Color white - (Color white alpha:0.5) = Color gray. > Color white - (Color white alpha:1.0) = Color black. > > For what do you need the color arithmetic ? > Maybe there are already other operations defined on Color that you can > used instead. > > As the arithmetic operations on Color doesn't work (for years?), maybe we > should remove > the operation now, and replace them with a more verbose api > addRGB/ addRGBA/ subRGBA .... > > nicolai > > Ah, this issue is already closed. That was a rather short discussion. And #/ and #* still don't work for colors.
> > > > > >> >> >> On Sat, Mar 21, 2015 at 3:41 AM, Ben Coman <[email protected]> wrote: >> >>> Do we need to do something for Pharo 4? And what is the >>> simplest/quickest thing that would work - even if it needs revisiting in >>> Pharo 5? >> >> >> The most simple that works is to at least set alpha to any value. >> >> - Multiplication - alpha doesn't change >> - Division - alpha doesn't change >> - Addition - (color1 apha + color2 alpha) min: 1.0 - simple addition >> and check to not allow alpha to overcome max value >> - Subtraction - if two colors are the same alpha becomes 0, otherwise >> we take alpha of message receiver (minuend) >> >> Slice is in inbox (15188) >> >> Cheers, >> Alex >> >> >
