1. A method for generating a virtual rig to animate a virtual three-dimensional representation of a human face, the method comprising: receiving a mesh that includes a plurality of vertices to provide a virtual three-dimensional representation of a human face, the plurality of vertices defining a plurality of polygons that define a virtual three-dimensional representation of a surface of the human face; associating a plurality of semantic identifiers with the plurality of respective vertices, each semantic identifier specifying a respective physical feature of the human face; generating a virtual rig that is capable of maneuvering the mesh to a plurality of configurations, using one or more processors, based at least in part on association of the plurality of semantic identifiers with the plurality of respective vertices to animate the virtual three-dimensional representation of the human face; determining that a virtual item is to be combined with the mesh to represent a corresponding item of the human face based at least in part on a designated subset of the plurality of semantic identifiers; and generating the virtual item based at least in part on a subset of the plurality of vertices that is associated with the designated subset of the plurality of semantic identifiers and further based at least in part on whether the virtual item is a first virtual eyeball that represents a first physical eyeball of the human face or a second virtual eyeball that represents a second physical eyeball of the human face; wherein at least one of a position, a size, or a shape of the first virtual eyeball and a respective at least one of a position, a size, or a shape of the second virtual eyeball are asymmetric with respect to the mesh to represent that at least one of a position, a size, or a shape of the first physical eyeball and a respective at least one of a position, a size, or a shape of the second physical eyeball are asymmetric with respect to the human face; and wherein generating the virtual rig comprises: defining a reference element based at least in part on the designated subset of the plurality of semantic identifiers and further based at least in part on a thickness of a virtual layer that is coincident with an outer surface of the mesh to serve as a reference for maneuvering the virtual item, the virtual layer being a virtual representation of skin that is coincident with the surface of the human face.