Re: [css-transforms] CSS3D breaks with opacity flattening

It's been a while since I have done 3d graphics programming, but isn't this
solvable as a 'render to texture' - a simple technique that dates back to
very early 3d game graphics? This should preserve-3d on the car frame for
the internal 3d perspective, no? You could even use a simple pixel shader
of you fancied having depth still working.

On Mon, 19 Sep 2016 9:41 am Rik Cabanier, <cabanier@gmail.com> wrote:

> On Mon, Sep 19, 2016 at 8:22 AM, Matt Woodrow <mwoodrow@mozilla.com>
> wrote:
>
>> On 19/09/16 6:27 PM, Tab Atkins Jr. wrote:
>>
>>> No, as I explained in more detail in the GitHub thread I linked
>>> <https://github.com/w3c/svgwg/issues/264#issuecomment-246750601>, this
>>> is a logical consequence of 'opacity' and other filter-type effects
>>> being "group effects".  If you want the effect to only apply to the
>>> leaves, you can do that yourself by specifying it on the leaves, but
>>> it has a visibly different effect than doing it "as a group".
>>>
>> Sorry, I'm not quite sure I follow. The idea I proposed explicitly
>> *doesn't* break the group nature of opacity, which is why I think it's
>> worth discussing.
>>
>> The example I gave had opacity applied to an intermediate element, and
>> showed the internal representation needed to apply it as a group while
>> maintaining preserve-3d.
>>
>
> What you're proposing will also change how content is rendered. :-\
>
>
>> Are there more complex examples you can think of where this breaks down?
>>
>> Obviously this would prevent depth sorting occurring between elements
>>>> inside
>>>> and outside of 'b', and we need to figure out how to depth sort 'b'
>>>> itself
>>>> (given that it is an atomic entry for sorting, but isn't a 2d plane),
>>>> but
>>>> those seem solvable.
>>>>
>>> That's actually the core problem preventing this from working; it's
>>> not a detail we can just paper over later.
>>>
>> Which part of this? The first piece is the exact same situation we have
>> when we flatten for opacity, so I don't see how that's a problem. The
>> latter is somewhat difficult from an implementation standpoint, but it's
>> not obvious that it's a showstopper.
>
>
> Why is that not a showstopper? Your proposal seems very difficult to
> implement since it pushes matrix manipulation all the way down to the
> individual elements.
> It also introduces more rendering surfaces.
> You're also relying on how firefox is representing the render tree which
> might be completely different from other UA's
>
> Browsers already have a hard time giving a consistent experience with the
> simple model and this will make it even more complicated.
>