Function S2Polygon.projectToBoundary

Return the closest point on the polygon boundary to the given point. If the polygon is empty or full, return the input argument (since the polygon has no boundary). "x" should be unit length.

s2.util.math.vector.Vector!(double,3L) projectToBoundary (
  in const(s2.util.math.vector.Vector!(double,3L)) x
);