Unreal Engine 4.11 Preview 1 发布渲染提升

Unreal Engine 4.11 Preview 1 发布，主要更新如下：

Rendering Updates:
- New physically based shading model for realistic hair based on the latest research from film. It models 2 specular lobes, transmission, and scattering.
- New physically based shading model for eyes.
- New physically based shading model for cloth. This combines the standard shading model with a layer of velvet fibers. This layer simulates fuzz and fabrics.
- Capsule Shadows – We now have support for very soft indirect shadows cast by a capsule representation of the character
- Lightmass Portals – Skylight quality indoors can be massively improved by setting up Portal actors over openings. Portals tell Lightmass where to look for incoming lighting, they don’t actually emit light themselves. Portals are best used covering small openings that are important to the final lighting. Placing large Portals all over the level will dramatically increase build times.
- Per-vertex translucency lighting – There are two new translucency lighting modes available in the material editor which compute lighting per-vertex. PerVertex lighting modes use half as many shader instructions and texture lookups.
- We now have support for 3 lighting channels. You can set which channels a PrimitiveComponent or a LightComponent is in.
- We’ve integrated Intel’s Embree ray tracing library into Lightmass and we got a huge lighting build speedup from it, as the majority of lighting build time goes toward tracing rays to figure out how light is bouncing.
- We’ve integrated updates to the D3D12 RHI to allow better CPU utilization while generating rendering commands in parallel.
- Improved quality and performance of the SubsurfaceScatteringProfile shading model.
- Circle Depth of Field post process – New Material Functions to render small particles with out of focus.
- Materials using separate translucency can now be rendered at a lower resolution, which can be useful to improve GPU performance for fillrate and overdraw heavy geometry (for example particle effects).
  The resolution is controlled via a console variable, r.SeparateTranslucencyScreenPercentage, which expresses separate translucency as a percentage of current screen resolution.
- Static mesh LOD transitions now supporting dithering.