Enable computation of geometric direct path diffraction for all sources that have diffraction enabled in the positioning tab of the authoring tab. This flag enables sounds to diffract around geometry (see AK::SpatialAudio::SetGeometry) that have diffraction edges. Diffraction edges must be enabled for sounds to diffract around geometry (see AkGeometryParams). If bEnableDirectPathDiffraction is false but a sound has "Enable Diffraction" ticked in the positioning tab of the authoring tool, the sound will only diffract through portals but pass through geometry as if it is not there.
AkSpatialAudio.h の 85 行目に定義があります。