- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Thu, 06 Apr 2023 20:49:48 +0000
- To: public-css-archive@w3.org
For the example given in the original post, the results would be: **1. (colors add in premultiplied oklab)** because - `color(display-p3 0.3 0.6 0.2 / 0.5);` is `oklab(0.603 -0.15 0.118 / 0.5)` which when premultiplied is `[0.3015, -0.075, 0.509]' - `oklch(0.5 0.2 140)` is `oklab(0.5 -0.15 0.129)` which is the same when premultiplied `[0.5, -0.15, 0.129]` - add oklab components: `[0.8015, -0.225, 0.638]` but wait, if I was interpolating then I would interpolate the alpha. But I am adding so do I add them? Interpolate them? _Not clear how to un-premultiply here_ and [8.1.1. Combination of `<color>`](https://drafts.csswg.org/css-values-4/#combine-colors) doesn't say, even for sRGB. @tabatkins any clues? I guess that adding `rgba(32, 64, 128, 50%)` and `rgba(128, 64, 32, 50%)` produces 50% alpha not 100% right? **2. specify that colors do not add** `color(display-p3 0.3 0.6 0.2 / 0.5);` because V&U 4 Combining Values: Interpolation, Addition, and Accumulation [says](https://drafts.csswg.org/css-values-4/#combining-values) > If a value type does not define a specific procedure for [addition](https://drafts.csswg.org/css-values-4/#addition) or is defined as not additive, its addition operation is simply V<sub>result</sub> = V<sub>a</sub>. -- GitHub Notification of comment by svgeesus Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/8576#issuecomment-1499606222 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Thursday, 6 April 2023 20:49:50 UTC