Wouldn't it be much easier to just make a new map?

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With the different colours for left/right irises "baked" in, instead of implementing a whole new UV/shader layout?

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Open the iris map in your image editor of choice and createA NEW IRIS DIFFUSE MAP, with the different irises left/right.

Apply that to the eyes and you're set.

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Why over-complicate things which can be solved with 20th-century methods?

Because something is "old 20th century technique" doesn't mean you must throw it away!

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Karina

(just another 20th-century relic...)