Re: WebVR and DRM

On Mon, Jul 10, 2017 at 6:42 PM, Brandon Jones <bajones@google.com> wrote:

>
>    - Occlusion is possible through careful stenciling and alpha channel
>    use, but not easy.
>
> I don't think stenciling or depth testing would be possible. In order for
it to happen in either direction, the stencil buffer or depth buffer has to
move from one webgl context into a "secure" webgl context. This might be
feasible on platforms that have no concept of such a context (which would
require secure memory) and where you could achieve "resource sharing". But
this is a workaround that does not exist on platforms with built-in
hardware DRM support (such as apple devices, android devices, etc.) where
data cannot move out or into the secure context from inesecure contexts
(that's what DRM mandates after all). Therefore stenciling/depth-testing
support would be limited to "legacy" platforms that implement the whole DRM
"ad-hoc" and don't make strong guarantees about accessability of data. I.e.
it's a workaround that would not work everywhere, and as such, would be
unsuited to the Web.