Are anisotropic highlights still using the material parameter collection and complex material networks, or has this been added as a for-real, supported material feature? If it’s been added as a feature…
-Does anisotropic specular reflection work with all light types? Does it work with area lights? Tube lights?
-Is there a limit on the number of lights which can be reflected by anisotropic materials?
-Are cubemaps sampled anisotropically as well? How is this being approached, and what are the trade-offs? What does does the quality look like?
-Does the standard material now support anisotropic direction inputs, or are they only active on special materials?
-Can we easily create common anisotropic materials other than hair, such as machine-tooled metals, skin, or cloth?
-What workflow does Epic use internally for artist-authored direction maps?
Does skin shading now support transmission from back-faces (such as ears)?
Have any of the errors with SSS been fixed, such as the outlines which would appear around non-scattering objects?
Do transparent surfaces (corneas, tear lines, eyeglasses) now have direct specular reflections? Do they support all light types/areas/tubes? Is this a standard part of the “Surface” translucent lighting mode, or will it have to be enabled via secret rites?
Will translucent surfaces (hair, fur, cloth etc) now receive detailed shadows, or will they still use low-frequency volume shadows?
Is there any support for order-independant sorting for translucent materials? If not, have any improvements been made to the existing sorting?
Has there been any progress towards a more hybrid deferred/forward renderer which would allow for special-case effects like retroreflection(for safety vests, animal eyes, etc), art-directed exclude/include lighting(which remains performant), or totally non-photo per-character/per-object lighting like in Guilty Gear?
Have any improvements been made to character shadowing? Can characters now cast area shadows?
How about indirect shadows, like in The Last of Us?
How about (non-screenspace) reflection occlusion, like The Order/Remember Me?
Have there been any improvements to character skinning/deformation?