His problem is that the geometry (if you take its shading literally) is impossible to represent in a 3d system. The same object is neither infront of, behind, or level to itself at the same time... its all three.

To the question: You might get away with blendshapes/animated textures to fake the shading. (Set it to the illumination channel in the shader so it doesn't light with the renderer, similar to a skybox)

But that probably violates the purpose.