How to put foam/mildew/dirt material on another material

Hi everyone ! :smiley:

My second topic for this question : :sweat_smile:

How to make foam/mildew/dirt material and put it on another material (AND I WANT TO SELECT EXACTLY THE PLACE WHERE I PUT THE FOAM//MILDEW/DIRT MATERIAL) (loud and clear :laughing:)

I have already my Sci-Fi material on this building part :


And i want to put some foam/mildew/dirt material in the yellow places

I want to put something that look approximately like that :

These brown or dark gray lines on my Sci-fi Material :upside_down_face:

I’ve try a few ideas to make it but didn’t get what I wanted :sweat:

This requires UV unwrapping but is the answer you’re looking for. If you want to avoid UV unwrapping and setting up a new texture, you can try vertex-paint, which you can use as a mask input to @grant.r.brown’s previous answer.

Good luck!

Could I get an image or screenshot (of the nodes), because I’m not sure to have all understand because I’ve try his option and didn’t get what I think it will be :sweat:

Exactly the same as @grant.r.brown’s node setup, but instead of the Noise Texture input use Vertex Color input and select your Vertex Color Layer from the dropdown.

In Grant’s example, the 1st method would have replaced the Noise Texture input with a UV-unwrapped Image Texture Node.

Good luck.

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There are a number of ways to create a mask for this kind of thing. I think you’re using Cycles ? you can use an inverted AO texture to single out the edges of the building, or a regular one (not inverted) to get the creases and other concave places of your building. Then pipe the output of this texture into a mixRGB node with your two textures (regular and dirt). Or as others have suggested you could directly paint a mask on your object, but it has to be unwrapped first. If you want to avoid that part then vertex painting is possible, but probably won’t be as accurate as texture painting (depends on your object definition).

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Great ! Finnaly get what I wanted, thanks a lot @zeroskilz and @Hadriscus for the help ! :hugs: