The Group thing is kind of how Illustrator used to create masks. Not sure anymore I’ve been out of Illustrator for years now.
Bob S > On Apr 15, 2020, at 12:02 PM, Richard Gaskin via use-livecode > <use-livecode@lists.runrev.com> wrote: > > Whenever I fail to add, "...or seemingly so based on 22 years of experience > in delivering applications with LiveCode, but of course notwithstanding the > full scope of all possible things one might try given infinite time", please > consider that implied. :) > > I'm not the first person to have work stopped on a feature when the older > inks were removed. > > Monte's suggestion, and you your explanation, are very helpful. I've passed > them along to another developer I know who held up some of their own work > when the method they'd been using was no longer available. > > The new inks are indeed quite good, and the group trick is a very helpful key > to unlocking how to use them well. Thank you. > > > > Just to explain why the group is necessary - if a group has the > > 'blendSrcOver' ink applied then it becomes a 'transparency group'. > > > > This means it has its own alpha channel which can be affected by the > > 'destination alpha modifying' porter-duff operations. So in this case: > > > > 1) The group is a transparency group so allocates its own > > transparent buffer > > 2) The image is composited into the buffer > > 3) The mask is then composited into the buffer with the DstIn ink. > > This means that the destination buffer alpha is adjusted so it is only > > 'in' the mask (an analog of ANDing the buffers alpha channel with the > > mask's alpha channel - indeed, previously I'm guessing you would have > > done this using some sort of AND bitwise ink and being careful with > > colors used). > > 4) The buffer is then composited with the background. > > > > The transparency group thing is needed partly for efficiency and > > partly because you can't remove alpha from an opaque destination > > - which a window provides. > > > > Hope this helps! > > > > Mark. > > -- > Richard Gaskin _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
