How to blend/mask materials?

Question

I've been working on the Blender Guru donut tutorial and want to add some variation to the condensation on the coffee cup. Currently the condensation stops very abruptly on the the inner rim of the glass, creating a harsh transition between the glass and the droplets.

Is there a way to mask or hide certain pieces of the condensation material in order to create a more irregular transition with the glass material? In other words, I want the droplets to be visible only on specific portions of each face, not the whole thing. I've seen that color ramp nodes can be used to create a fade/gradient effect between materials, but am unsure how to accomplish this using my water normal map.

My current node setup:

Thanks in advance for your help!

Answer 1

Sure, that's the whole point of shading, you create noise patterns and then use them to guide blend or strength input parameters. Here a example:

Separating Uv coordinates makes a gradient in the chosen direction, add centeri it in the plane and then mix it with a noise on linear light mode. Then use that to guide any blend or parameter. 1 of the millions of ways you can mix values to generate masks, the core technique of shading.