Cycles Change only part of an objects viewport color

I have an eye that has a transparent cornea as part of the eye. I would like to be able to view where the iris is on the eye without having to resort to render shading to help with the animation. The actual iris is another part of the mesh below the cornea thus doesn’t show up at all in the 3d viewport. Is there a way in cycles to color only part of the object in the 3d viewport. I know I can shade the material of the cornea, but it then turns the entire object that color in the material setting. Is there a way to shade just part of the object in the 3d viewport?

Here is a blend with the eye.

http://www.pasteall.org/blend/42027

My actual character file is linked in to about 20 other files. So I"m looking for a quick way to be able to change the viewport only shading, not the eye itself.

You can mask the cornea out in the viewport with the mask modifier.

Thanks, that will get me going. Now if only I can figure out how to turn that on and off in the linked file only without turning off all of them, I’m good to go. But this gets me a lot closer, thanks.

Not sure if I get what you mean.

It’s the linked library issue. If you proxy the armature, then you won’t have any access to the modifiers in the linked file. If you are rendering on a few computers with the character while working on another animation in a different file with the linked character, then if the issue becomes one of either not rendering or not using the mask when animating. If I were doing this on just one computer, it wouldn’t be an issue.

Set the mask modifier to only apply to display, and not render. You can’t edit a linked mesh, so edit cage visibility doesn’t apply. If you really need to access the visibility of the mask set a driver on it linked to a property on the armature.

If you have two materials: one for the cornea and one for the rest, you can set a viewport color with 0 alpha for the cornea material. This should work even after you make it a proxy, just make sure to: Properties --> Object–> Display --> check transparency, and set Maximum draw type to solid.