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I find it interesting to note that the core fuchsia OS comes with "magma", "escher" and "scenic", which seems to be core OS services for composing one 3D scene across multiple processes ("shadows can be cast on another process without it knowing about it")

Is that a hint that Fuchsia is a VR-first operating system?

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Not really, that's how Windows works too since Vista.

https://msdn.microsoft.com/en-us/library/windows/desktop/aa9...

And it's what enables effects like this in Windows 10:

https://docs.microsoft.com/en-us/windows/uwp/design/style/re...

Disclaimer: I work for Microsoft

I don't think what Windows provides is really comparable. By my understanding (and the documentation you linked seems to back this up) WDM is responsible for taking 2D framebuffers from applications, and compositing them into a (possibly 3D) scene. Fuchsia's Scenic operates uses a 3D scene graph as its input.

This article has some details about that:

https://9to5google.com/2018/04/06/fuchsia-friday-graphics-ga...

Scenic will have support for what it’s calling “stereo cameras.” What this means is there can be two views into the same scene. Each camera can also be independently moved or turned for a different view. The most obvious reason for this capability is virtual reality.

I would say it is more of an hint that the material design team was heavily consulted when Fuchsia was conceived.

Drop shadows in 2D window managers are pretty common, is it not referring to that?

From the sound of it, I assumed it was building up a 3d world scene graph composed by objects supplied by independent processes. Maybe I'm reading too much into it.

Yeah I think the "physically based 3D renderer" is a bit misleading because it makes you think "ah, like Blender or Unreal Engine 4", but actually I think they just mean they are doing window translucency and drop shadows in a physically correct way (e.g. there is an actual light source) rather than faking it. It is still used to render mostly-2D windows.

(This is my assumption anyway - I haven't tried running it)

I think you assumption is spot on.

Android already does physically correct soft shadows in real time.

The initial design of material would have allowed way more space manipulations, like making a view rotate on any axis.

So the shadow implementation allows to remain correct even in this kind of case.

It is kinda sad that the final design forbids this, a simple raster shadow would have been enough to just signify the elevation.

I always figured this was to support Material Design, where the size of a drop shadow depends on the difference in elevation between the surface casting the shadow and the surface underneath.[1] A Material Design compositor would have to know the position of each process' surfaces in 3D space in order to render shadows correctly.

[1]: https://material.io/guidelines/material-design/elevation-sha...

I want to downvote you for using VR first OS, which is technobabble, however I want to upvote you for sharing useful info about the topic. So I did neither.

Augmented reality pretty much requires us to shrink displays down to contact lens sizes because we already figured out almost nobody will pay to strap a smartphone to their face.

Then it requires us to create and popularize an entire new method of interacting with your computer.

Then this needs to be cheap enough to get in everyone's hands.

It would be surprising if this only took 20 years.

This is about drawing dumb drop shadows.

We could argue about the difference between OS and presentation layer but that battle may already be lost.

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