Tangents only calculated on UV0?

Are there any plans to support tangent calculation for multiple UV sets? As it stands, normal maps linked to other UV sets often don’t light correctly.

As of 4.11 there is a material function called “Derive Tangent Basis” that you can use to derive a tangent basis based on a specified UV set. Here is some more info copied from an internal email that will hopefully make it over to docs soon:

A limitation in UE4 is that normal maps have to use UV0 or they will be incorrect because the engine only stores one set of tangent vectors from UV0. This is a material function that can derive new tangent vectors using the specified UVs so that you can use a normal map with any UV channel.

Note that for this node to work, your material must be set to “Tangent Space Normal = FALSE” since the function returns a World Space Normal. If you need to combine this normal with another normal that is using UV0, the UV0 normal needs to be transformed from Tangent to World."

That’s fantastic news. Thanks!

I’d like to add (hence unlocking comments) that this still isnt in the docs. (at least, i cant find it)
would’ve been nice to find there as I could have used it many versions ago.