If true, normal reprojection from the previous frame is allowed in SceneTexture nodes on DBuffer decals, provided that motion in depth prepass is enabled as well (r.VelocityOutputPass=0). Otherwise the fallback is the normal extracted from the depth buffer.
Usage
r.Decal.NormalReprojectionEnabled [value]
Set via the console (~) or in DefaultEngine.ini / DefaultGame.ini.
