Ambient Fog Light leaves Zone Brushes (root object, same pose) and Sector Tint.mat moves from
PowerBrush to Brushes/Ambient Brush: brightness falls as exp(-x^2 ln(1/_EdgeBrightness)), x in
units of Zone.PopulatedRadius. ZoneRenderer.FitAmbientLight, called by LoadZone, is the one
writer of the quad's size and _Reach (the radius where it is 1e-5 of the centre). AmbientEdgeVerify
renders the real scene object through that call. Builds in Unity 6000.3.24f1.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
