- From: Tab Atkins Jr. via GitHub <sysbot+gh@w3.org>
- Date: Fri, 22 Nov 2024 20:00:13 +0000
- To: public-css-archive@w3.org
> And I don't quite follow the argument about affine spaces, and don't think compositing is restricted to coordinates that have a meaningful concept of scaling. Ultimately, the final output is a weighted sum of values, and if the weights sum to 1 then I don't see a fundamental mathematical problem. You can probably *composite* in any space in theory (I'm not sure, but I'll take your word for it), but you can't do *premultiplication* in color spaces with affine coordinates (this I'm 100% sure of). Pre-multiplication is fundamentally a scaling operation, and you can't scale affine coordinates; there is no value of hue angle that means "0deg red, but half as much". As a very specific example, there is *no* value of "pre-multiplied" hue angle that you can use for `transparent` that will have the same effect as doing pre-multiplied interpolation in RGB (that is, every color in the transition has the *other* endpoint's hue). This is why we have the notion of "missing" hue in the Color 4/5 interpolation rules, so that we can at least handle the common/trivial cases (a literal `transparent`, etc) as expected, even if it doesn't scale to "nearby" (mostly-transparent) colors. -- GitHub Notification of comment by tabatkins Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/11238#issuecomment-2494697838 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Friday, 22 November 2024 20:00:14 UTC