New to shaders, having a hard time wrapping my brain around this

Unity Engine
1

I am an artist, with limited scripting knowledge (Mel, AS2), and i need a little help.

My problem is that i am thinking of blending textures and such in terms or RGB and Alpha, and i cannot figure out how to differentiate them.

My example problem:

I have a basic vertex lit shader. I want to have a Diffuse texture with an alpha and a mask texture with no alpha.

I want to LERP the Diffuse(1) and the DiffuseAlpha(0) with the mask texture

I cannot figure out how to refer to the Diffuse alpha vs the diffuse rgb. This is what i want overall:

SetTexture [Diffuse]
{
constantColor [Mask]
combine Diffuse lerp(constant) DiffuseAlpha
}

I know DiffuseAlpha is not the right syntax of course, i just dont know how to tell unity i want to reference only the alpha of the diffuse. I hope this makes any sense.

2

What you’re saying and displaying in code doesn’t make a whole lot of sense to me (for example, you’re saying you have a “mask texture” but your code says it’s just a constant color), but here’s some information I think you’re asking for: