Re: [csswg-drafts] should it be possible for an element with contain:paint to be part of a transform-style:preserve-3d scene? (#6202)

The CSS Working Group just discussed `should it be possible for an element with contain:paint to be part of a transform-style:preserve-3d scene?`, and agreed to the following:

* `RESOLVED: add contain:paint to list of grouping properties`

<details><summary>The full IRC log of that discussion</summary>
&lt;dael> Topic: should it be possible for an element with contain:paint to be part of a transform-style:preserve-3d scene?<br>
&lt;dael> github: https://github.com/w3c/csswg-drafts/issues/6202<br>
&lt;dael> TabAtkins: The summary is when you have a preserve3d transform nothing prevents a contain:paint participate in the 3d scene.<br>
&lt;dael> TabAtkins: A bunch of properties restricted to force it to become flat so children are container<br>
&lt;dael> TabAtkins: contain:paint should work the same<br>
&lt;smfr> overflow does NOT create a graphical group<br>
&lt;dael> TabAtkins: Spec also allows overflow-clip to have children leave element entirely and florian pointed out that doesn't make sense.<br>
&lt;smfr> q+<br>
&lt;dael> TabAtkins: If we're having overflow:contain-paint to cause flattening we should have them both<br>
&lt;dael> TabAtkins: Prop: add contain-paint to list of grouping properties that force it to be flat. Remove clip value form exceptions so it also causes it to be flat<br>
&lt;dael> smfr: I think this is right thing. I think contain-paint causes stacking but should flatten<br>
&lt;dael> smfr: I think TabAtkins said non-visbile overflow creates stacking?<br>
&lt;Rossen_> ack smfr<br>
&lt;dael> TabAtkins: Overflow-clip is on list of values that don't cause flattening. Feels weird. I think it should<br>
&lt;chrishtr> agree that clip and contain:paint should cause flattenign<br>
&lt;dael> smfr: That's fine. I agree with proposal<br>
&lt;TabAtkins> s/overflow-clip/overflow:clip/<br>
&lt;dael> dbaron[m]: I agree as well<br>
&lt;dael> Rossen_: Other feedback or objections?<br>
&lt;dael> smfr: Prop to make coverflow:clip a grouping property. Impl it creates stacking context?<br>
&lt;dael> florian: DOn't think so<br>
&lt;dael> smfr: Think it does<br>
&lt;dael> dbaron[m]: We do have that grouping prop create stacking context. That said, I wrote a test a few weeks ago to see what rbowsers made group. Tested with transform flattening and mixed blend and got entirely different results in all browsers.<br>
&lt;dael> dbaron[m]: Given that I think we don't have a good sense of grouping<br>
&lt;dael> smfr: Testing with opacity or filters might have given more consistent<br>
&lt;dael> smfr: I don't want to separate grouping from stacking context. Would create complexity<br>
&lt;dael> florian: I don't think the grouping are defined to create stacking<br>
&lt;dael> dbaron[m]: Don't have a spec for this. I did have understanding that the set of things grouping is subset of things that create stacking<br>
&lt;dael> TabAtkins: Happy to remove overflow:clip part and just do contain-paint<br>
&lt;dbaron[m]> the test I'm talking about was https://dbaron.org/css/test/2018/stacking-context-z-order<br>
&lt;dael> smfr: contain-paint can imply overflow:clip. Would love overflow properties that create stacking, but that ship has sailed<br>
&lt;dael> Rossen_: TabAtkins just resolve on contain:paint and leave overflow:clip for now?<br>
&lt;dael> TabAtkins: Yes<br>
&lt;dael> Rossen_: That's the proposal. thoughts or objections?<br>
&lt;dael> florian: Thought; maybe misunderstanding. Seems it's not necessary for overflow:clip to flatten a 3d transform b/c can position in 3d model. If when it's time to paint the projection is outside area you paint you clip<br>
&lt;dael> smfr: Please don't make clipping a thing we nee din 3d scenes<br>
&lt;smfr> q+<br>
&lt;dael> Rossen_: Great convo that should happen when additional investigation of overflow:clip takes place<br>
&lt;dael> smfr: If we resolve on this do we need to resolve on if will-change contains side effects. From dbaron[m] chart it does nto have stacking.<br>
&lt;dael> TabAtkins: Can you open as separate issue?<br>
&lt;dael> smfr: Yes<br>
&lt;dael> Rossen_: not hearing objection sot contain:paint<br>
&lt;dbaron[m]> I think will-change's definition is pretty clear about what's supposed to happen...<br>
&lt;dael> RESOLVED: add contain:paint to list of grouping properties<br>
&lt;dael> Rossen_: Anything else on this?<br>
</details>


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Received on Wednesday, 9 June 2021 16:49:31 UTC