One sub-shader in a mix shader is always blank

[Anonymous]

I have a mix shader combining together two sub-shaders (also mix shaders) with an alpha map like so.

But when the eye_shader is applied to an object, the area that should be covered by the iris_shader is blank white.

If I apply either one or the other of the two sub-shaders directly to an object, they render as expected.

iris_shader:

eye_background:

The alpha map is a simple transparent png with a black area.

I don't understand how the iris_shader can render as blank in the mix shader when it works fine on its own.

[lee_griggs]

What happens if you use a .jpg instead?

[Anonymous]

Swapped to using a jpg colour channel, no change.

[Stephen.Blair]

Can you upload a scene?

[Anonymous]

https://easyupload.io/qe76df - zipped with the required textures

[Stephen.Blair · Accepted solution]

Here's what I got using a layer shader instead of the mix.

I also changed the shading tree a bit (I used pupil.png for the mix mask, and a color correct to invert it).

eye.v2.ma.zip

[Anonymous]

It works great using the LayerShader with the ColorCorrect to invert the mask, thanks!

Any idea why it works with the LayerShader but not with the MixShader? I've been using MixShaders because they don't require the extra step with the ColorCorrect node.