(* Return the closest base object intersecting the given ray, and
   the curvilinear abscissa t of the intersection point.
   Return None if no intersection.
   Return t = 0.0 if the viewpoint (origin of the ray) is inside an
   object.
   boolean true = return first object if ray starts inside
   boolean false = ignore first object if ray starts inside. *)

val intersect_ray:
  Point.t -> Vector.t -> Object.t -> bool -> (float * Object.base_object) option