Is there any way to mask out parts of a texture to make it a different colour to the rest?

Question

Been following this really great tutorial from "Critical Giants" on how to make procedural planets, and to begin, I wanted to try making an Earth-like planet.

While I've got a decent understanding of how these nodes work together, I'm not exactly sure how I could go about making the top land mass white (as if it was the north pole), or even how I'd make certain parts of the planet different colours (like parts of the ocean green, making certain land masses more green than others, etc). Is there a way to mask out that particular area of the texture? Kind of like how you would do it in After Effects or Photoshop?

For reference:

https://pasteboard.co/DmuhMHn5WOSF.jpg - current render of the planet

https://pasteboard.co/WoJH1F8cLSKO.png - nodes (just for the planet, atmosphere & clouds are separate models)

This has all been done in Eevee.

Hopefully, that made sense, and thanks for anyone's help in advance!

Answer 1

You can use Black and White values to control which color or shader gets passed through a mix node. Plug black and white values(non-color) to the factor socket in the node editor.

This doesn't have to be pure Black and white values, any light/dark values will work. If you already have an image texture, try tweaking making the brighter values brighter and darker values darker with curves node and use them as a factor map.

Procedural texturing is a topic on its own, an example : Here I have used the math node to add two Gradient textures which resulted in a new gradient texture, and then used that resulting gradient to mask out parts of a checker texture.

Answer 2

To add to Agnivesh's answer, if you need to mix 2 materials that have different shaders (for example you need to mix 2 Principled BSDF that have different settings), mix them through a Mix Shader, with your black and white image or noise as factor: