Re: Modules split

FYI, I filed https://github.com/immersive-web/webxr/issues/788 "Clarify
`environmentBlendMode` semantics" which includes some of the discussions in
this thread.

On Mon, Aug 5, 2019 at 1:17 PM Klaus Weidner <klausw@google.com> wrote:

> On Mon, Aug 5, 2019 at 10:55 AM Rik Cabanier <rcabanier@magicleap.com>
> wrote:
>
>> On Mon, Aug 5, 2019 at 9:40 AM Brandon Jones <bajones@google.com> wrote:
>>
>>> I'm working on a more complete response, but I'm taking some time to
>>> make sure that I'm not innacurately representing anyone's position or
>>> offering any conflicting messages. But for the moment I want to make sure
>>> we're clear on the use and purpose of *environmentBlendMode:*
>>>
>>> We heard from the HoloLens team that they wanted to have the ability to
>>> display what was then the equivalent of *"immersive-vr"* content, but
>>> provide developers a hint to determine how it would actually be shown in
>>> order to allow them to either tweak the content for that scenario or
>>> possibly optimize it by avoiding rendering certain things that wouldn't
>>> display properly anyway (ie: certain shadow effects.) Thus by allowing
>>> *"immersive-vr"* sessions to specify an *"additive"*
>>> *environmentBlendMode* headsets like HoloLens or Magic Leap are allowed
>>> to advertise support for VR content if they so choose. It's also perfectly
>>> valid choice for a given platform to choose not to do that if they don't
>>> feel the user experience will be a positive one, as you indicated.
>>>
>>
>> It would be good to hear from Microsoft why they wanted this (and not
>> just use 'immersive-ar').
>> Maybe we can continue this on github? I filed an issue there.
>>
>> FWIW I think *environmentBlendMode *should only be meaningful in an
>> 'immersive-ar' session. https://www.w3.org/TR/webxr/#xrsessionmode-enum already
>> implies this
>>
>
> Just to avoid confusion, please keep in mind that the environmentBlendMode
> is a read-only property that's set by the device depending on hardware
> properties and the requested session type. It is NOT a developer choice
> that's selected by an application.
>
> There's no way for an application to request "immersive-vr with additive
> blend mode". The application just asks for immersive-vr, and the UA
> either picks the most-opaque blend mode that it supports (reporting this
> back to the application through the blend mode property), or rejects the
> session if it does not support immersive-vr.
>
>