Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Reference
GV_HAIR_INTERSECTION_OBJECT
Parameter: Mode
GV_HAIR_INTERSECTION_MODE
Parameter: Velocity Mode
GV_HAIR_INTERSECTION_VELOCITY_MODE
Parameter: Position
GV_HAIR_INTERSECTION_INPUT_POSITION
Parameter: Velocity
GV_HAIR_INTERSECTION_INPUT_VELOCITY
Parameter: Radius
GV_HAIR_INTERSECTION_INPUT_RADIUS
Parameter: Intersection
GV_HAIR_INTERSECTION_INTERSECTION
Parameter: Guide
GV_HAIR_INTERSECTION_GUIDE
Parameter: Segment
GV_HAIR_INTERSECTION_SEGMENT
Parameter: Segment Delta
GV_HAIR_INTERSECTION_SEGMENT_T
Parameter: Ray Delta
GV_HAIR_INTERSECTION_RAY_T
Parameter: Position
GV_HAIR_INTERSECTION_POSITION