Function fovray_c 

pub unsafe extern "C" fn fovray_c(
    inst: *const c_char,
    raydir: *mut ConstSpiceDouble,
    rframe: *const c_char,
    abcorr: *const c_char,
    obsrvr: *const c_char,
    et: *mut SpiceDouble,
    visible: *mut SpiceBoolean,
)