How do your greyscale textures work, exactly?

[rasputin1963]

Hey gang,

This is a bit of dumb n00B question,  but here goes:

Some Corona Material fields,  as we know,   are asking you for a greyscale pattern (procedural or bitmap) from whence they can derive their numeric values.   That I understand.

What I am unclear on is:     In Normal blending mode,  Do the greyscale values supplant (completely take the place of and override) the slider percentages above them?     ie.,  white=100%,  black=0%

Or do the greyscale values take into consideration the already  dialed-in percentages above them?   Thus,  in the specific case of my screencap here,   does a pure white value give me the currently selected slider percentage value,  ie  42.1%... and all in-between grey values get interpolated between 0% and 42.1%  ?

I hope I'm making sense here.

Thanks,  ras

[mmarcotic]

Hello,

in short, yes (for Physical material, at least).

a bit more in-depth:
Whenever you see a (0,1) interval in our material's UI, you can expect that this value is going to multiply the shader input (white == 1, black == 0). This does not apply to our Legacy material though, that was written in a way that whether there is a shader input, it overrides all other settings for that particular parameter.

Example Physical material:
Base layer>Roughness (or glossiness, which is just = 1 - roughness). If I add a controlling Gradient shader and set the value to 25%, the result is, as you said, an interval between (0, 0.25) - similar behaviour would be attained by changing the black node in gradient to 25% gray.

Example Legacy material:
Reflection>Glossiness. If I add a controlling Gradient shader and set the value to 25%, the result is (0,1) because the shader overrides the numerical setting.

We are aware that the two different behaviours are not very consistent when looked at side by side. We have decided to move in the Physical material behaviour for the future, as we do not want to spend more development time in the Legacy material apart from bugfixing. Whenever a shader is inputted in the Physical material, the controlling level parameter is set to 1, so that the initial experience is identical for Legacy and Physical, and also allows for further tweaking.

Please note, that this concerns only those parameters which are in the (0,1) range (or 0% - 100%). Parameters with different values, such as IOR, SSS radius, etc. will follow different behaviours, which are exclusive to these settings.

I hope this clears some things up.

Thanks,
Jan

[rasputin1963]

Thanks so much,  Jan,  very informative.