Re: [csswg-drafts] [css-values-4] How to interpolate min/max/clamp? (#4082)

The CSS Working Group just discussed `How to interpolate min/max/clamp?`, and agreed to the following:

* `RESOLVED: For interpolation math functions are treated as atomic algebraic terms. You interpolate a calc expression that is the weighted sum of all the terms`

<details><summary>The full IRC log of that discussion</summary>
&lt;dael> Topic: How to interpolate min/max/clamp?<br>
&lt;dael> github: https://github.com/w3c/csswg-drafts/issues/4082<br>
&lt;dael> AmeliaBR: I agenda+ it, though thinking of it for next week.<br>
&lt;dael> AmeliaBR: We're starting to get consensus, at least TabAtkins and I and Alan C agree<br>
&lt;dael> AmeliaBR: We have new mask functions including these functions. We don't have anything that defines how work in animations and transitions. They generally work on computed values and these functions exist at computed time so need to define how to interpolate<br>
&lt;smfr> s/mask/math/<br>
&lt;dael> AmeliaBR: Proposal is that interpolation would be a linear interpolation of the terms where the functions on the initial side of interpolation are scaled to to multiplied by 0 and on the result side the scaled up from 0 to 1. Intermediary result is the sum of those terms<br>
&lt;dael> AmeliaBR: Important benefits of the approach is you can define the intermediary value as a computed value without needing to sub in values from layout. And you can do mathematical simplification and it won't change result<br>
&lt;dael> AmeliaBR: If author wants different interpolation like changing power and want power interpolated instead of results they can do by custom properties and interpolate the custom prop rather then final mathematical expression<br>
&lt;dael> Rossen_: Other comments or thoughts?<br>
&lt;dael> AmeliaBR: Prop: For interpolation math functions are treated as atomic algebraic terms. You interpolate a calc expression that is the sum of all the terms<br>
&lt;dbaron> weighted sum, I hope :-)<br>
&lt;dael> Rossen_: Okay. Any objections?<br>
&lt;fremy> LGTM<br>
&lt;dael> AmeliaBR: Yes, weighted sub by the interpolation factor<br>
&lt;dael> s/sub.sum<br>
&lt;dael> s/sub/sum<br>
&lt;TabAtkins> Aka, if interpolating between any two expressions A and B, the interpolation is *defined as* calc(.X*A + (1-.X)*B) (plus any algebraic simplifications)<br>
&lt;svoisen> jensimmons: There are links for both calendars at the bottom of this message https://lists.w3.org/Archives/Member/w3c-css-wg/2017OctDec/0076.html<br>
&lt;dael> RESOLVED: For interpolation math functions are treated as atomic algebraic terms. You interpolate a calc expression that is the weighted sum of all the terms<br>
</details>


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Received on Wednesday, 10 July 2019 16:08:26 UTC