Specular maps in the diffuse alpha

A weird question that has been bugging me. Is there any advantage to putting the specular map in the alpha channel of the diffuse texture when it’s already in the alpha channel of the normal texture?

So far as I know, no.

Phong reading the specular from the diffuse behaves identically as reading it from the normal, according to the Valve Developer Wiki.

But I wouldn’t take my word for law. Someone far more experienced with materials, such as Ageha or BlueFlyTrap, would be a far stronger authority on this than I am.

can’t you have two different specular maps for one material that uses normal mapping, by putting a phong specular in the diffuse, and the envmap specular in the normal map? I think I’ve heard it’s possible…

It’s reading from the normal, I just want to know if putting the specular in the diffuse as well results in some visual improvement.

Visually there is no difference between which one you use. Unless compression is involved but even then it is pretty minor unless you’ve downsized to a very low resolution.
The command exist for optimization purposes should your model lack a normalmap. Should both be present and/or the basealpha needs to be occupied with something else there is no reason not to use the normalalpha.

Save for unless you need multiple specular. At that point it would be more efficient to store any additional specular as 8bitalphas on top of the existing specular in the normalapha and alternate them as needed.

Alright, I will take that into account. Thanks to all of the people who posted here.
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