The documentation about this is unclear.
FMOD_Geometry_SetPolygonAttributes allows to set directocclusion and reverbocclusion, and FMOD_System_GetGeometryOcclusion is also returning these.
What does it do internally?
Does it trace a single direct line between listener and viewer? If so does it return the properties of the first polygon hit (from the source). Does it integrate over all polygons in the path?
Or does it something more sophiticated outside of a direct line trace?