* Distance field building is now asynchronous and stored in the DDC separately from static mesh data.
* Added OcclusionMaxDistance and Contrast properties to Movable sky light
* Using the GBuffer normal instead of the generated distance field normal, fixes artifacts on two-sided materials and between modular pieces. Also saves about .7ms / 4.5ms
* Points in the distance field are only considered 'inside' the mesh if > 50% of all rays traced hit a backface. Most meshes can have a valid distance field generated with this heuristic. Meshes without a distance field representation can receive occlusion.
* Fortnite two-sided foliage with world position offset animation works fine now
* Using the resulting bent normal for diffuse lighting, improves consistency in occluded corners
* Resulting bent normal is also used to occlude skylight specular using an approximate cone-cone intersection, prevents leaking where SSR is not available
* Fixed stationary skylights not getting lightmap mixing
* Reflection captures now work with the movable skylight, which adds its diffuse contribution to IndirectIrradiance so their lightmap mixing works
* Added new show flag to visualize mesh distance fields, which ray traces through the distance fields and gives a sense of their shape
[CL 2276435 by Daniel Wright in Main branch]
#ttp 340613 - FIXIF: EDITOR:ANALYTICS: Static Mesh Editor Instrumentation Pass
#branch UE4
#added Added analytics for various static mesh editor usage, making sure not to spam events when spinboxes are used and only report when the value actually changes.
#added Added analytics whenever an asset is reimported (if via an editor, the editor will then report that it was it that did the reimporting)
reviewed by Thomas.Sarkanen
[CL 2229618 by Andrew Brown in Main branch]
#ttp 340526 - Static mesh editor: changing the static meshes normals setting from "import normals" to "compute normals" doesn't change the mesh until the user reimports the asset
#branch UE4
#add Added button to reimport based on the current import options (no button will appear if there are no options to modify)
#change Modified import options so they get marked as dirty until they are reimported (button will be unclickable unless they are)
reviewed by Thomas.Sarkanen
[CL 2217535 by Andrew Brown in Main branch]
* Provides mid-range stable AO for dynamic rigid meshes
* Movable sky lights are now supported, and distance field AO is used for shadowing Movable sky lighting from dynamic scenes
* Static meshes are preprocessed into signed distance field volumes at mesh build time when the r.AllowMeshDistanceFieldRepresentations project setting is enabled
* Non-uniform scaling does not work with this method (mirroring is fine), animating through world position offset also causes artifacts as the two representations diverge
* Occlusion is computed along cones to reduce over-shadowing, object distance fields are operated on directly (no hierarchy) to obtain enough resolution to prevent leaking, visibility traces are done with cone stepping to allow better parallelization, and shading is done adaptively in space and time using the surface cache.
[CL 2093556 by Daniel Wright in Main branch]
#ttp 335786 Lighting: Assigning a Material in the Staticmesh editor unbuilds lighting on placed meshes
reviewer Thomas.Sarkanen
[CL 2093124 by Andrew Copland in Main branch]
#ttp 319896 - Skeletalmesh/Staticmesh LOD refactoring: Part 1 (Refactor Static Meshes to use ScreenSize rather than distance)
#branch UE4
#change Removed LOD Distances and added ScreenSize for Static Meshes
[CL 2065408 by Benn Gallagher in Main branch]
