GetPrecomputedShadowMasks
Engine\Shaders\Private\LightmapCommon.ush
Shadowmask
https://docs.unity3d.com/Manual/LightMode-Mixed-Shadowmask.html
GetPrecomputedShadowMasks
Engine\Shaders\Private\LightmapCommon.ush
https://docs.unity3d.com/Manual/LightMode-Mixed-Shadowmask.html