Reflection Actors#

Buildtime scene cubemap captures projected onto spheres/boxes
Can nest them and at run time, shader will interpolate between them to fake parallax correct reflections
Obviously has light leak b/c it doesn't take into account local occlusion
Does not provide dynamic or sharp refletions
Updated dynamically in the editor but locked in game mode
Different glossy levels point to different parts of the mipmap chain
Roughness material parameter is used to blend between indirect diffuse lightmap data and the reflection cubemap (i.e. fully rough = using purely lightmap indirect data)
Lightmap data should not include direct lighting for this to work (otherwise you get double lighting) i.e. turn off static lights when baking lightmap data and only use stationary lights
https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/ReflectionEnvironment/index.html

Reflection Environment: provides indirect specular

indirect meaning specular from other objects in the scene. Direct meaning from the lights
Direct specular through analytical lights & skylight
Needs lightmass to build indirect diffuse lighting (so it can sample it to calculate indirect specular)

HiddenPrimitives on FSceneView