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Hello community,

I have a probably simple question which I am not able to explain to myself right now.

I am working on a Glass shader for a bottle of water. I have my bump for some details and everything is working good so far. To add more realism in the appearance I wanted to
create hmm...a scratchy, matte area,



which happens because bottles in the factory are kind of hitting each other or when the machines are moving them like here




So..when I connect a colortexture into the transmittance slot, i get a green glass with a still transparent greyish area. But when i connect a black/white texture to determine the transparency of the areas (green is full transparent and the grey as very very little transparent) then how do I change the color to green back since then I have a white glass with a black nontransparent area? Puting the color texture into the 0 degree or 90 degree reflection slots doesnt help. Do I need a new layer for that? or just another bsdf? I could not solve that by new layers for some reason. Its no problem for me to do that in mental ray but here the terms are different and there are some "slots missing"

Would appreciate any help.

Thank you for reading.

Cheers

What you want to do is increase the roughness for just those areas -- so you would load a greyscale map in the roughness slot. No need to alter transparency... just green glass with a roughness map will do it.

Best,
Jason.

Ok, but then my glass will be still green on those rough areas. Or am I getting something wrong?

Exactly, the glass is still green in the real world as well... it's just a rougher green glass.

Roughness will impact the perceived opacity and the surface of the glass should be neutral (grey/black not green) to be correct.

The easiest way to get a good glass is just use the wizard "low grade" glass and decrease the attenuation value to 3 cm(or lower) with whatever color transmittance fits your need.

The greyscale roughness map should be fairly high contrast with the black/dark areas representing the normal (smooth) parts of the glass and white/light areas representing the damaged bits... Then just increase the roughness value until you get satisfactory results.

Best,
Jason.

Here's an example MXM:

http://www.spotoarts.com/jason/damagedglass.zip

Best,
Jason.

Why not just use a second layer with a weight map? This way it's easy controlling those rougher grey areas since they are on a separate layer.