Here is a cool facial rigging with projected 2D like facial texture mapping, but a closer look at it, it is not a texture, it is shader setup more like vector drawing which doesn’t pixelate when zooming. Very neat and an intuitive way of 2D like facial setup on 3D model. You can find the tool here.

Below is a tutorial on setting up the eye using this tool.

TBM2D creating_the_eye from The Beast Makers on Vimeo.