Re: [css-transforms] Handling combined opacity and preserve-3d

> On May 28, 2016, at 2:12 pm, Chris Harrelson <chrishtr@google.com> wrote:
> 
> 
> On Thu, May 26, 2016 at 4:09 PM Matt Woodrow <mwoodrow@mozilla.com <mailto:mwoodrow@mozilla.com>> wrote:
> 
> On 27/05/16 5:03 AM, Chris Harrelson wrote:
>> 
>> Hi Matt/Simon/Rossen/all,
>> 
>> I'm the lead for paint/compositing integration in Blink.
>> 
>> TL;DR:
>> - Blink/Chrome would like to change its implementation to have opacity force flattening, and AIUI match what Firefox was doing before this Mozilla bug <https://bugzilla.mozilla.org/show_bug.cgi?id=1250718> wax recently fixed.
>> - We'd like other implementations to make the change also if there is consensus.
>> 
>> As noted already in this thread, this changed behavior matches the latest spec, is more well-defined and rational, and significantly reduces the complexity of Blink's implementation. (Matt, from reading the Mozilla bug, I think you would agree?)
>> 
>> Other implementers: does this change sound good? Would you be willing to commit to changing behavior if it is web compatible enough? (We are already collecting compatibility data in the Canary & Dev channels).
>> 
>> Here is one example:
>> Before <http://jsbin.com/tabuxo/edit?html,output>
>> After <http://jsbin.com/tekuratiba/1/edit?html,output>
>> 
>> Our work is tracked in this bug <https://bugs.chromium.org/p/chromium/issues/detail?id=612956>.
> 
> Firefox only temporarily had that behaviour, it was a regression due to a refactoring we did. We reverted to matching the current Blink/WebKit behaviour since we had reports of real sites breaking because of it.
> 
> So far the data seems to show a very small impact. I'll update next week with some actual numbers.
>  
> 
> I do agree that this change is the preferable behaviour though, so will be interested in the results of the compatability data you're collecting.
> 
> Great. Simon/Rossen, what do you think?

I think that it makes logical sense that opacity forces flattening, and am willing change WebKit accordingly.

Simon