- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Tue, 18 Apr 2023 13:54:00 +0000
- To: public-css-archive@w3.org
> For analogous components it would be good to verify if `a` and `b` have analogous components. For example between `lab` and `oklab`. > As currently specified these do not Ah, good point. Lets see: `lab(50 0 100)` is `oklab(0.564 -0.03 0.156)` while `lab(50 100 0)` is `oklab(0.603 0.316 0)` so it does seem reasonable to treat `a` and `b` as analogous. > Chroma is powerless when lightness is 0% because any chroma value results in the exact same color (black). (And maybe the same is true of white, I forget the outcome of our conversation about this earlier.) Once we got rid of the ill-fated attempt to deal with CIE Lightness as potentially going up to 400% then yes, the same is true of white. And we have WPT for that (which didn't get tagged with Interop2022 because it had already started, and which all browsers fail): - [lch-009.html](https://github.com/web-platform-tests/wpt/blob/master/css/css-color/lch-009.html) for CIE L = 100 - [oklch-009.html](https://github.com/web-platform-tests/wpt/blob/master/css/css-color/oklch-009.html) for Ok L = 1.0 - [lch-010.html](https://github.com/web-platform-tests/wpt/blob/master/css/css-color/lch-010.html) for CIE L = 0 - [oklch-010.html](https://github.com/web-platform-tests/wpt/blob/master/css/css-color/oklch-010.html) for Ok L = 0 > Some edits were made but it doesn't seem that everyone agrees on these? Firstly, it seems that [Powerless components](https://drafts.csswg.org/css-color-4/#powerless) should include the example @tab gave above with Chroma becoming powerless when Lightness is at the ends of the range. Then, this is what the spec currently says, and it should say `powerless` for saturation/chroma (and add examples): > If the saturation of an HSL color is ''0%'', then the hue component is [=powerless=]. If the lightness of an HSL color is ''0%'' or ''100%'', the hue component is [=powerless=] and the saturation is ''0%''. > If the chroma of an LCH color is ''0%'', the hue component is [=powerless=]. If the lightness of an LCH color (after clamping) is ''0%'', or ''100%'', the hue component is [=powerless=] and the chroma is ''0''. > If the chroma of an Oklch color is ''0%'' or 0, the hue component is [=powerless=]. If the lightness of an Oklch color is ''0%'' or 0, or ''100%'' or 1.0, the hue component is [=powerless=] and the chroma is ''0''. Lets get consensus on the spec for this aspect, then pull WPT into alignment with that. -- GitHub Notification of comment by svgeesus Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/8609#issuecomment-1513201576 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Tuesday, 18 April 2023 13:54:02 UTC