elements:
HUD_ELEM_GSI
HUD_ELEM_MINIMAP
HUD_ELEM_RETICLE
HUD_ELEM_WEAPONS
HUD_ELEM_CASH_RESPECT_HOMEY
HUD_ELEM_WEAPON_SWAP_MESSAGE
HUD_ELEM_RADIO_STATION
HUD_ELEM_VEHICLE_NAME
HUD_ELEM_DIVERSIONS
HUD_ELEM_MESSAGES
HUD_ELEM_SCREEN_FX (Must be explicitly hidden (does not hide with HUD_ALL_ELEM))
HUD_ELEM_SUBTITLES (Must be explicitly hidden (does not hide with HUD_ALL_ELEM))
HUD_ALL_ELEM (Set the fade level for all HUD elements)
fade levels:
HUD_FADE_HIDDEN
HUD_FADE_TRANSPARENT
HUD_FADE_VISIBLE
HUD_FADE_NO_CHANGE (keep the existing fade level for the element, base on the previous HUD state)