[Bug 16349] backface-visibility underdefined

https://www.w3.org/Bugs/Public/show_bug.cgi?id=16349

--- Comment #3 from Simon Fraser <smfr@me.com> 2012-03-14 18:03:20 UTC ---
(In reply to comment #2)
> Please say if Safari on Mac displays red in any of these cases, and if so, why
> you think it's right:
> 
> Test-case 5:
> 
> data:text/html,<!DOCTYPE html>
> <style>div { width: 100px; height: 100px }</style>
> <div style="-webkit-transform: rotateX(180deg);
> -webkit-transform-style: preserve-3d; background: lime">
>   <div style="-webkit-backface-visibility: hidden; background: red">
>   </div>
> </div>

> WebKit nightly on Windows 8 displays red in test-case 5, which I think is a
> bug.  (It gets all the rest right.)  In support of the fact that this is a bug,
> adding -webkit-transform: scale(1) to the inner div in that test-case makes
> both the WebKit nightly and Chrome-with-GPU-acceleration display green. 
> Firefox had this bug too until version 13; the problem is that it was assuming
> that since there was no transform specified on the element, it didn't have to
> pay attention to 3D rendering separately from the parent, so it didn't look at
> backface-visibility.
> 
> If Safari on Mac gets all of these test-cases right, then it probably matches
> my proposed spec change too.

Agreed; this is a bug. position:relative also works around it.

I'm trying to find out exactly what Safari's implementation does. This example:

data:text/html,<!DOCTYPE html>
<style>div { width: 100px; height: 100px } </style>
<div style="-webkit-transform: rotateX(180deg);">
  <div style="-webkit-transform-style: preserve-3d; background: lime">
    <div id="bf" style="-webkit-backface-visibility: hidden; background: red;
width: 50px; margin-left: 30px; position: relative;">Test</div>
  </div>
</div>

implies that it's as you've written.

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Received on Wednesday, 14 March 2012 18:03:26 UTC