wait a sec why Alpha affects the Color ? o_O
Color white - (Color white alpha:0.5) = Color gray. What ? No ! This make no sense Color white - (Color white alpha:0) = Color white Ok reasonable Color white - (Color white alpha:1.0) = Color black. again reasonable On Sun, Mar 22, 2015 at 4:06 PM, Aliaksei Syrel <alex.sy...@gmail.com> wrote: > 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. > > > That is too complicated :) > The idea was to have one-line fix that just leaves the behaviour as it was > before, simply makes it not produce garbage. > Basically there should be a long discussion after pharo 4 is released. > > How it is now: > (Color white alpha: 0) = Color transparent => false > Color white - (Color white alpha: 0) = Color black => true > > From logical point of view is should not be black. But from mathematical > point of view Color is just a vector and operations with it should be the > same or almost the same as with vectors. > > For what do you need the color arithmetic ? > > I wanted to get linear discrete transformation from one color to another > to use it in animation > > Cheers, > Alex > > On Sun, Mar 22, 2015 at 1:54 PM, Marcus Denker <marcus.den...@inria.fr> > wrote: > >> >> On 22 Mar 2015, at 13:35, Nicolai Hess <nicolaih...@web.de> wrote: >> >> >> >> 2015-03-22 12:43 GMT+01:00 Nicolai Hess <nicolaih...@web.de>: >> >>> >>> >>> 2015-03-21 15:51 GMT+01:00 Eliot Miranda <eliot.mira...@gmail.com>: >>> >>>> Why not take the average of alpha in all cases? >>>> >>>> Eliot (phone) >>>> >>>> On Mar 21, 2015, at 6:32 AM, Aliaksei Syrel <alex.sy...@gmail.com> >>>> 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. >> >> >> Yes… I think we have a problem that there is no “this is ready for >> integration” check. >> >> We need to get more careful… >> >> Marcus >> > >
