pub type ManifoldSdf = Option<unsafe extern "C" fn(arg1: f64, arg2: f64, arg3: f64, arg4: *mut c_void) -> f64>;
enum ManifoldSdf { None, Some(unsafe extern "C" fn(_: f64, _: f64, _: f64, _: *mut c_void) -> f64), }
No value.
Some value of type T.
T