Please disregard the excessive changes in platform_win32.cmake - that must have been a merge gone wrong.

Also add to the list of "known issues": Embree's object motion blur only does linear interpolation, not arc interpolation like Cycles' BVH. The blur of fast rotations will look different.

Not sure having abstraction over ray intersection is really great idea: it is really preferable to preserve render result (at least ,result to which render converges to) for all supported devices.

For the complex scenes/motion blue memory usage and speed, wondering whether it is due to STBVH [1]. And in general, is it due to better quality of BVH itself, or there is really something really different is happening in the traversal (comparing with BVH8+bucketed triangles from Max/Via/Anton). Still think using Embree builder will make it a huge difference on GPU (there seems to be a bug in our OOBB/BVH split which was producing rather poor quality BVH, which i never had time to fully investigate).

Anyway, that is all technical, and maybe it'll be easier to talk about in person at the conference :) For now, think it's fair enough to ask for some numbers ;) Like, benchmark suite + something with moblur rendered with current master BVH8 and Embree. Reporting device/peak memory + render times.

Adding Maxym here as well.

[1] https://embree.github.io/papers/2017-HPG-msmblur.pdf

All BVHs are going to give identical results, unless they're broken. Likewise, the differences between separate implementations of a given ray/triangle intersector (Möller–Trumbore, Woop, ...) will also only differ in floating point rounding. As long as we're compiling with fast-math turned on, our results will not be bit-perfect across compilers anyway. Hair curves have small differences (caps, self-intersection epsilon), if we need perfection we could just implement the same intersection everywhere (Embree and DXR/OptiX allow for user defined geometry).

Regarding numbers:
Agent 327, 07_04_F.lighting.blend, frame 162. Dual Xeon 2660v2
No Embree: 16m03s, 7142MB
With Embree: 4m48s, 6161MB

Will this Embree implementation pave the way to a Cycles CPU + GPU option in the OptiX section of the Blender Preferences, like in the the CUDA section?

No, that's unrelated.